Investigation of Eating Actions of People With Dementia From the Viewpoint of Self-Awareness

Abstract

The key to improve the quality of life of people with dementia and caregivers is whether caregivers can understand the meanings of the puzzling words and deeds of people with dementia. Therefore, 2 of the authors observed and wrote down the puzzling words and deeds of 28 people with dementia in eating scenes, and these words and deeds were interpreted using our original model consisting of “theory of mind,” “self-evaluation,” and “self-consciousness.” The results indicated that the bases for why caregivers perceive the words and deeds of people with dementia in eating scenes as puzzling are (1) those unable to pass the task of self-evaluation cannot evaluate their own eating situations in comparison with social standards, and the food culture collapses and (2) those unable to pass the task of self-consciousness cannot perceive through their senses.

Introduction

There are currently 36 million people with dementia living in the world. The number of people with dementia is expected to increase rapidly in low-income and middle-income countries in the future, causing the total number of individuals with dementia to reach 66 million in 2030 and 115 million in 2050. ¹ Approximately 2 million people with dementia live in Japan, ² and numerous difficulties in caring for these people are known to exist, with people with dementia accounting for nearly 80% of elderly individuals abuse victims in domestic settings. ³ The major causes of abuse are triggered by behavioral and psychological symptoms of dementia (BPSD), behavior that puzzles caregivers, and an increase in the mental burden of caregivers arising from an inability to communicate. ⁴ The prevention of abuse and improvement of the quality of life of people with dementia and their families have become urgent issues worldwide. Improving the understanding of caregivers regarding the meanings of apparently puzzling words and deeds spoken or performed by people with dementia during daily life, such as BPSD and communication difficulties, may be a key to solving this issue.

Among daily life actions, the ability to eat is retained in people with dementia up until the very last stages of the disease. ^5,6 However, apparently puzzling words and deeds spoken or performed while eating begin to appear with the progression of dementia, and the care of such patients subsequently becomes difficult. For example, they may complain insistently that they have not yet eaten, although in reality they ate only a short time earlier. They may eat with their fingers or spill food on the table and floor. They may stop eating during the meal. Even when a spoon is brought to their mouths, they may not open their mouths. They may hold food in their mouths but not swallow, and it may take more than 1 hour to finish eating. They may put something other than food, such as a wet towel, into their mouths. According to the operative definition for the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), ⁷ dementia leads the patient to marked impairments in social or professional competence as a result of (1) memory disturbance and (2) one or more of the following impairments: aphasia, apraxia, agnosia, or executive dysfunction, resulting in a marked decrease in the patient’s functional levels compared with the levels exhibited before the development of the disease. However, the above-mentioned puzzling behavior cannot be explained only by focal symptoms, such as memory disturbance, apraxia, and agnosia. Despite the fact that the levels of memory disturbance are almost the same, some people with dementia complain that they have not yet eaten their meals, while others do not. Although the retention of intelligence is a presupposition of aphasia, apraxia, and agnosia, the abovementioned puzzling words and deeds while eating appear after dementia has progressed considerably. Therefore, the phenomenon of holding food in the mouth but not swallowing cannot be explained by swallowing apraxia. Furthermore, the phenomenon of putting something other than food, such as a wet towel, into the mouth cannot be explained by agnosia. In other words, dementia is not simply a combination of impairments in intellectual functions, such as memory disturbance, agnosia, and apraxia, but a state in which intelligent participant integrating these intellectual functions is invaded, ⁸ and the words and deeds of people with dementia cannot be understood by analyzing these intellectual functions independently. ⁹

In previous studies of eating and swallowing disorders in people with dementia, the relationship between gastrostomy and prognosis, ^{10 –13} the analysis of functional disorders in the oropharyngeal phase according to the disease type (such as Alzheimer’s-type and vascular dementia) using video fluoroscopic examination of swallowing and the incidence of pulmonary aspiration, ^{14 –18} and dementia as a risk factor for aspiration pneumonia ^{19 –21} have attracted interest. However, the puzzling words and deeds spoken and performed by people with dementia while eating that can cause conflict with caregivers, possibly leading to the abuse of people with dementia by their caregivers, have not received much attention. Only a few studies have explained dementia by analyzing agnosia and apraxia, ²² but no approach has ever been made from the viewpoint of intelligent participant, which integrates the participant’s own intellectual functions.

Intelligent participant means ego and self-awareness. However, the concept of ego differs among scholars. Accordingly, to understand the words and deeds of people with dementia, which can be very difficult to explain or understand, we have focused on the self-awareness of people with dementia and intelligent participants who integrates their own intellectual functions and have created a “model for interpreting puzzling words and deeds of people with dementia from the viewpoint of self-awareness.” ^{23 –25} The purpose of the present study was to explain the means of these puzzling words and deeds spoken or performed by people with dementia while eating using our model and to present viewpoints understandable to caregivers.

The self can be grasped from 2 aspects: the self (I) as the participant of consciousness and action and the self (me) as an object of consciousness. ²⁶ Using car navigation as an analogy, the artificial satellite that detects the position of the car and leads the driver to the destination represents the self as the participant, while the moving car is the self as an object. Dementia is considered to be a state in which the car wanders and cannot arrive at the destination because of the dismantling of the artificial satellite or the participant.

This model for interpreting the puzzling words and deeds spoken or performed by people with dementia from the viewpoint of self-awareness consists of a “developmental model of cognition and emotion” by the developmental psychologists Lewis and coworkers ^27,28 and the “theory of mind” by psychologists Wimmer and Perner ²⁹ (Figure 1). According to Lewis, human beings are born with emotions of “contentment,” “interest,” and “distress” and emotions such as “joy,” “sadness,” and “fear” developed as a result of relationships with others. At an age of approximately 1½ years, “self-consciousness” arises, enabling the close observation of one’s self and the ability to distinguish between the self and others; this leads to the development of emotions such as “embarrassment” and “empathy.” Furthermore, at 2½ to 3 years old, children begin to understand the rules and standards of the society in which they live, and they acquire the function of “self-evaluation” that judges whether their thoughts and actions are good or bad in comparison with the rules and standards. Thereafter, emotions such as “shame” and “guilt” may develop. In addition, humans assume the actions of the mind in the background of others’ behavior, ³⁰ and Wimmer and Perner ²⁹ revealed that the children can acquire the theory of mind, which is the ability to estimate psychological states (intention, thought, belief, desire, emotion, preference, etc) that are in the background of the behavior of self and others and cannot be directly observed ³¹ at an age of 4 to 6 years.

Figure 1.

Development process of self-awareness of infants (compiled from Lewis’s developmental model of cognition and emotion and Wimmer and Perner’s theory of mind).

Self-awareness constitutes the basis of sociality. ³² In other words, the development of self-awareness is thought to form the basis by which infants adapt to human relations, becoming conscious of their own existence with the awakening of self-consciousness, and distinguishing themselves from others. This process further prepares them for adaptations to the social rules and standards by which they live, enables them to make self-evaluations and allows them to adapt to human relationships with an unspecified large number of people by presuming the minds of others based on the theory of mind. Thus, self-consciousness, self-evaluation, and the theory of mind were included in the present model as developmental stages necessary for the self-awareness that is required for adaptations to human relationships.

The one viewing this developmental model conversely is “a model for interpreting puzzling words and deeds of people with dementia from the viewpoint of self-awareness” (Figure 2).

Figure 2.

Model for interpreting puzzling words and deeds of people with dementia from the viewpoint of self-awareness.

Methods

Participants

The test participants were 29 persons who had been diagnosed as having dementia among 50 residents of a certain nursing home for the elderly individuals. Among these 29 persons, the only test participant who passed the task for the theory of mind was excluded from the analysis. As a result, the number of test participants was reduced to 28 (mean age, 86.7 ± 6.5 years; 2 men and 26 women; 15 patients with Alzheimer’s-type dementia, 12 patients with vascular dementia, and 1 patient with dementia with Lewy bodies).

For ethical considerations, the research protocol was submitted to the director of the surveyed facility, and the study was performed with the approval of the ethics committee of the facility.

Methods

Evaluation of the eating function and self-awareness ability was performed by 2 of the authors using the procedure described below. In addition, evaluation of the severity of impairment in general cognitive function was performed by the care worker.

Evaluation of Eating Function

Each of the 2 authors sat at a table with a different set of participants, observed 1 or 2 participants who were eating at the same tables that they usually ate at, from the beginning to the end of lunch or dinner scenes, and wrote down their puzzling words and deeds.

All participants were in the same room, and 3 to 4 participants sat at a round or square table. For participants requiring assistance, two-to-one or one-to-one assistance was provided by the caregivers.

Evaluation of Self-Awareness Ability

The evaluation was performed in a quiet place, with consideration given to the ability of the test participants to maintain their attention and the degree of their hearing loss.

The methods used to evaluate self-awareness are explained below.

Evaluation of the presence or absence of theory of mind

An evaluator and a test participant sit at a table across from each other, and the evaluator shows the test participant 4 picture cards (Figure 3), in which the “false-belief” task by Wimmer and Perner ²⁹ is understandably illustrated using figures drawn by Muto. ³³ The evaluator slowly reads out the contents of Figure 3, using a finger to point to each scene on the card. If the test participant responds, “the round box,” to the final question of the task, the participant is evaluated as possessing theory of mind.

Figure 3.

Assessment of the presence or absence of theory of mind.

Scene 1. “There are a round box and a square box in front of Taro and Hanako. A bean-jam bun is contained in the round box.”

Scene 2. “Taro is leaving the room.”

Scene 3. “In the meantime, Hanako has transferred the bean-jam bun from the round box to the square box.”

Scene 4. “Taro has come back. In which box, the round box or the square box, does Taro think the bean-jam bun is in?”

Evaluation of the presence or absence of self-evaluation

An evaluator and a test participant sit at a table across from each other, and the evaluator shows the test participant 4 pairs of picture cards (Figure 4) that were created to evaluate the test participant’s understanding of the basic rules and standards of Japanese society; 1 pair of card is shown at a time. After confirming that the test participant has paid attention to the cards, the evaluator slowly reads out the contents of the picture cards, using the name of the test participant for XXX. For female participants, cards depicting the same scenes with female characters are used. If the test participant correctly answers all the 4 tasks, the test participant is evaluated as having self-evaluation.

Figure 4.

Assessment of the presence or absence of self-evaluation.

Task 1. “Mr. XXX is washing his hands after using the toilet,” and “Mr. XXX does not wash his hands after using the toilet.” Which is better?

Task 2. “Mr. XXX is quarreling with his friend,” and “Mr. XXX is getting along well with his friend.” Which is better?

Task 3. “Mr. XXX is wearing his clothes in public,” and “Mr. XXX has not put his clothes on, and is naked in front of everybody.” Which is better?

Task 4. “Mr. XXX is eating while standing,” and “Mr. XXX is eating while sitting.” Which is better?

Since the self-evaluation ability is acquired at 2½ to 3 years of age, according to Lewis, we validated in advance that these tasks are achievable for a large majority of nursery school children at 2 years and 11 months of age or older using the same picture sequences, but with children as the central characters.

Evaluation of the presence or absence of self-consciousness

The test participant’s name ³² (last name and first name), which is the core of one’s perception of self and others and is a symbol that indicates the reality of each person, as well as a different person’s name and a meaningless sound, such as “ahh,” were uttered from behind the test participant. The participant’s response to the sound (whether the participant answered) or whether the participant turned around to see where the sound had come from was noted. If the test participant answered or looked back only in response to his or her name, the test participant was evaluated as having self-consciousness.

Evaluation of the Severity of Impairment in General Cognitive Function

The severity of impairment in general cognitive function was evaluated for individual test participants by the care worker who was in charge of that test participant and who was familiar with the participant’s 24-hour life pattern; the evaluations were performed using the Clinical Dementia Rating (CDR). ³⁴

Analysis Methods

First, the test participants were classified into 4 stages according to the presence or absence of theory of mind, self-evaluation, and self-consciousness (test participants who passed the task of theory of mind, test participants who did not pass the task of theory of mind but passed the task of self-evaluation, test participants who did not pass the task of self-evaluation but passed the task of self-consciousness, and test participants who did not pass the task of self-consciousness). Next, the features of the eating scene for all the test participants classified in each stage were placed in order and were interpreted based on this model and the actual observations of the eating scenes.

Results and Discussion

The features of the participants’ behavior were first summarized for each of the 3 groups to make it easier to understand the context of each stage; each case was then described and discussed.

Eight Participants Who Did Not Pass the Task of Theory of Mind But Who Passed the Task of Self-Evaluation

Features

1. Test participants often spoke words that belittled themselves.

2. Test participants did not try to eat dropped food.

3. Some test participants tried to catch dropping food with a plate in their hands.

4. Test participants with a poor appetite did not try to eat the meal.

5. There were occasions on which the test participants did not understand the intentions and intelligence of others.

Case 1

A woman in her 80s diagnosed as having Alzheimer’s disease, CDR: moderate

The patient used a wheelchair to move independently. She ate all the food items with a spoon without dropping anything. When she finished eating, she pushed the tray forward and watched the others eating. When a staff member asked her, “What was in the meal?” she answered, “Various things” and looked into the bowl.

Case 2

A woman in her 80s diagnosed as having Alzheimer’s disease, CDR: moderate

The patient moved around independently with a cane. She ate all the food items with chopsticks. She picked up dropped food items with the chopsticks and collected them on the edge of the tray. When she finished eating, she left the table, went back to her room, and laid on her bed.

Case 3

A woman in her 70s diagnosed as having Alzheimer’s disease, CDR: moderate

The patient moved around independently with a cane. When she was asked to perform the self-awareness task, she answered with an uncertain look on her face, “I am not sure whether I will understand it.” While performing the actual task, when she was unable to understand task, she asked about the task with a stern look on her face; when she was able to understand, she answered with a smile. While eating, she put down her chopsticks every time she took a bite, and she ate the meal slowly. When she dropped rice grains on her leg, she picked them up with her fingers, put them back in the bowl, and did not eat them.

Case 4

A woman in her 80s diagnosed as having vascular dementia, CDR: moderate

The patient moved around using a wheelchair and required total assistance. When she was asked to perform the self-awareness tasks, she shyly answered, “I cannot do anything difficult.” She ate her meals with a spoon, and she showed a tendency to put more food into her mouth, while she still had food in her mouth. In addition, since she ate only the food on the plate just in front of her, she needed assistance to move other plates in front of her. She ate food dropped on her apron with her fingers and a spoon.

Case 5

A woman in her 90s diagnosed as having Alzheimer’s disease, CDR: moderate

The patient used a wheelchair and required total assistance. She ate her meals with a spoon, but her eating speed gradually slowed down. After a while, she hung her head and completely stopped eating. When a staff member asked her, “Don’t you want to eat any more?” she answered, raising her voice, “I am eating very well.” In addition, she tried to eat a large amount all at once, and she dropped food from her mouth. She caught the dropped food with a plate in her left hand.

Case 6

A woman in her 80s diagnosed as having Alzheimer’s disease, CDR: moderate

The patient used a reclining wheelchair to move around and required total assistance. When she was asked to perform the self-awareness tasks, she answered, “I am a fool, and I do not know.” She was able to eat by herself, but she had no appetite. When the meal was served, she did not eat, saying, “I do not want to eat.” When the author tried to lift the lid of the soup bowl, she stopped the author with her hand, saying, “No.” After a while, she opened the lid of the soup bowl by herself, but she just looked inside and put the lid back on the bowl. Finally, she ate less than half and said, “Thank you for the meal. I am a selfish old bag.’

Case 7

A woman in her 70s diagnosed as having Alzheimer’s disease, CDR: severe

The patient used a wheelchair independently. She told a person with severe dementia who was hitting a desk, “Don’t do that. Please feel sorry for the desk. Hit your own head instead.” She ate her meals with a spoon. With respect to collage making during the afternoon recreation time, the author asked her, “Do you participate in collage making, Ms. XXX?” and she answered, “No, I don’t, because I am already a fool.”

Case 8

A woman in her 90s diagnosed as having Alzheimer’s disease, CDR: severe

The patient used a wheelchair and required total assistance for mobility. She was almost totally dependent on the staff for eating. When a caregiver brought a spoon to her mouth, she sometimes refused to eat by grasping the caregiver’s hand firmly. When the author told her, “Ms. XXX, let’s eat,” she answered, “I am eating.” In addition, she asked the author many times, “Did you eat?” When the author replied, “Yes, I did,” she said, “Ah, really.” After the meal, she repeatedly rubbed a dirty spot on the cup with a finger as if the dirt on the cup bothered her.

Discussion

From the above representative case reports, we can consider that, at this stage, the representation of the self is retained, that the test participants recognize a decline in their intelligence, their situations in the eating scene, and their appetite, and that they can evaluate their behavior in comparison with social standards.

Statements such as, “I am not sure whether I will understand it” (case 3), “I am a fool, and I do not know,” “I am a selfish old bag” (case 6), and “I am already a fool” (case 7) suggest that these patients have recognized a decline in their intelligence.

The scene in which a test participant pushes the tray forward after the meal (case 1), the scene in which the test participant catches food dropped from her mouth with a plate in her left hand (case 5), and the scene in which when the test participant is told, ‘Let’s eat’ and she answers, “I am eating” (case 8) suggest that the participants recognize the eating scene.

The scene in which the test participant did not eat the meal, saying, “I do not want to eat,” and in which she stopped the author from lifting the lid of the soup bowl with her hand, saying, “No” (case 6) suggests the recognition of a loss of appetite.

In addition, at present in Japan, people do not eat food, except some foods such as rice balls, with their fingers, and never eat dropped food. The scene in which the test participant picks up dropped food items with chopsticks and collects them on the edge of the tray (case 2) and the scene in which the test participant picks up rice grains sticking to her leg with her fingers and puts them back in the bowl without eating (case 3) suggest that the participants are capable of evaluating their behavior in comparison with the standards of Japanese society.

Since, as described above, the test participants recognized their eating situations and appetite and could evaluate their behavior in comparison with the standards of Japanese society at this stage, there were almost no words or deeds spoken or performed during the eating scenes that the caregivers could not understand.

However, as seen in the example in which when a caregiver asked the test participant, “Don’t you want to eat any more?” and she answered, raising her voice, “I am eating very well” (case 5) and the example in which another patient told a patient with dementia who was hitting a desk, “Don’t do that. Please feel sorry for the desk. Hit your own head instead” (case 7), some of the representative cases with dementia exhibited “egocentrism” in the sense that since they have an incomplete theory of mind, which is the ability to presume the intentions behind others’ behavior and others’ intelligence, they cannot put themselves in another’s place, as described by the developmental psychologist Piaget. ³⁵ As a result, they are considered to act without consideration for others.

Eight Participants Who Did Not Pass the Task of Self-Evaluation But Who Passed the Task of Self-Consciousness

Features

1. Test participants did not pay very much attention to dropped food.

2. Test participants did not try to get rid of rice grains sticking to their chin or other body parts.

3. Test participants ate dropped food with their fingers, and some test participants licked their plates.

4. Test participants were unable to understand the intentions of caregivers and, in addition, were unable to control their emotions, showing violent behavior.

Case 9

A woman in her 90s diagnosed as having vascular dementia, CDR: severe

The patient walked independently, but she was totally dependent at mealtimes. She held a doll in her arms all the time. She was unable to spoon food and bring it to her mouth very well, and she dropped food on the doll. However, she did not seem to care about such things.

Case 10

A woman in her 90s diagnosed as having Alzheimer’s disease, CDR: severe

The patient used a wheelchair and required total assistance to move around. She ate her meals with a spoon, but she picked up and ate food that had dropped on her apron with her fingers. She tried to spoon food from empty plates and, moreover, she licked the empty plates.

Case 11

A man in his 90s diagnosed as having Alzheimer’s disease, CDR: severe

The male patient moved his wheelchair around by himself. He ate rice gruel and side dishes with chopsticks and a spoon. A staff member told him, “You eat only side dishes; you will have no side dishes left when you come to eat the rice,” but he remained silent and continued to eat only the side dishes.

Case 12

A woman in her 80s diagnosed as having Alzheimer’s disease, CDR: severe

The patient used a wheelchair and required total assistance to move around. When she was urged to eat, she held a plate and a spoon in her hands and tried to eat, but she dropped almost all of the food. After that, a caregiver brought a spoon to her mouth, but she scarcely opened her mouth. She traced the tray with her finger and then repeated a movement that looked as if she was collecting something on the tray.

Case 13

A woman in her 90s diagnosed as having vascular dementia, CDR: severe

The patient used a wheelchair and required total assistance to move around. As far as eating was concerned, she ate her meals with a spoon by herself and was almost independent. However, when she was slow at eating, she needed to be urged. In addition, when a caregiver tried to take her spoon from her hand to help her eat, she became angry, saying, “What are you doing?” and slapped the caregiver’s hand 3 times.

Case 14

A woman in her 70s diagnosed as having vascular dementia, CDR: severe

The patient used a reclining wheelchair to move around and required total assistance. Since she took a long time to eat, she was almost totally dependent on her caregivers for eating. Sometimes, she ate with a spoon by herself, but in some cases, she stopped eating while keeping the food on the spoon in her hand. When rice grains stuck to her chin, she did not try to get rid of them.

Case 15

A woman in her 70s diagnosed as having vascular dementia, CDR: Severe

The patient used a reclining wheelchair and required total assistance. Even when she still had food in her mouth, she put another heaped spoonful of ground food into her mouth, and she dropped much of it on her apron. She never looked at the dropped food.

Case 16

A woman in her 80s diagnosed as having vascular dementia, CDR: severe

The patient used a reclining wheelchair and required total assistance to move around. She tried to eat the meal with a spoon, but she dropped much of it. However, she did not seem to care about having dropped the food, and she ate the dropped food with her fingers.

Discussion

At this stage, the representation of the self was thought to become obscure and the test participants’ self-awareness ability was thought to be reduced so that the participants are barely conscious of their eating situation and cannot evaluate their behavior in comparison with normal social standards.

The scene in which the test participant drops food on a doll but does not seem to care (case 9), the scene in which the test participant eats only side dishes (case 11), the scene in which a caregiver brings a spoon to the test participant’s mouth but the participant hardly opens her mouth (case 12), the scene in which the test participant slaps the hand of a caregiver who is trying to help her eat (case 13), and the scene in which the test participant does not try to remove rice grains sticking to her chin (case 14) suggest that the participants’ consciousness of their eating situations has been obscured.

The scene in which the test participant does not care about her appearance or demeanor to others, that is, the scene in which she picks up and eats food that has been dropped on her apron with her fingers and licks the emptied plates (case 10) suggests that the test participant cannot evaluate her behavior in comparison with the standards of Japanese society.

As described above, since self-evaluation, that is, introspection, has become markedly reduced or has disappeared at this stage, the representation of the self becomes obscure and the test participants are unlikely to be conscious of their eating situations. As a result, the test participants were probably unable to realize that they were dropping food, to pay attention to rice grains sticking to their chins, or to open their mouths for a spoon that had been brought to their mouths. Furthermore, as shown in Figure 2, the emotion of shame is speculated to have disappeared at this stage, and the loss of the emotion of shame is considered to be a cause of the inability to care about what others think about their actions, such as eating dropped food and licking empty plates. In addition, as seen in the scene observed for case 13, since the test participants have lost the theory of mind that presumes others’ minds, they cannot understand the caregiver’s intent to provide assistance and, furthermore, since they cannot introspect on their emotions, they cannot control their emotions and their anger easily turns to acts of violence.

Twelve Participants Who Did Not Pass the Task of Self-Consciousness

Features

1. Test participants did not pay attention to spilled food at all.

2. A spoon was brought to the test participants’ mouths, but the test participants did not open their mouths.

3. Test participants held food in their mouths without swallowing.

4. Test participants put wet towels or their aprons into their mouths and mumbled.

Case 17

A Man in his 80s diagnosed as having Alzheimer’s disease, CDR: severe

The patient used a reclining wheelchair and required total assistance to move around. He was totally dependent for eating. He often kept his eyes closed. When a spoon was touched to his lips, he opened his mouth, but he ate with his eyes closed. When a caregiver shook his shoulder, he opened his eyes, but soon after he would close his eyes again.

Case 18

A woman in her 90s diagnosed as having vascular dementia, CDR: severe

The patient moved around in a reclining wheelchair and required total assistance. She was totally dependent for eating. She kept her eyes closed during the meal. Even when a spoon was touched to her lips, she scarcely opened her mouth. When food was put into her mouth using a little force, she mumbled.

Case 19

A woman in her 90s diagnosed as having vascular dementia, CDR: severe

The patient moved around with a reclining wheelchair and required total assistance. She was totally dependent for eating. During the meal, she repeated a movement in which she used her chopsticks to catch an empty space and then brought the chopsticks to her mouth, as if she were having a visual hallucination. When a caregiver brought a spoon to her mouth, she grasped the caregiver’s hand as if she refused to eat. Food was sticking to her hands, but she did not seem to care. She repeatedly looked around restlessly. After a while, she licked her hands, and then she began to lick the plates.

Case 20

A woman in her 90s diagnosed as having vascular dementia, CDR: severe

The patient moved around in a reclining wheelchair and required total assistance. She was totally dependent for eating. Even when a spoon was brought to her mouth, she did not open her mouth. When a spoon was touched to her lips, she opened her mouth about 1 in 10 times. When a caregiver tried to put a spoon into her mouth using a little force, she closed her mouth.

Case 21

A woman in her 80 s diagnosed as having vascular dementia, CDR: severe

The patient used a reclining wheelchair to move around and required total assistance. She was almost totally dependent for eating. She put a wet towel into her mouth and mumbled. When the author tried to take the wet towel away, she shook off the author’s hand and continued the movement. In addition, while she was licking the handle of a spoon, the spoon went deep into her throat and she shed some tears.

Case 22

A woman in her 80s diagnosed as having vascular dementia, CDR: severe

The patient moved around in a reclining wheelchair and required total assistance. She was almost totally dependent for eating. She always tried to put something into her mouth. She held a towel in her mouth before the meal, she put her apron into her mouth and mumbled during the meal, and she licked empty plates and her fingers after the meal.

Case 23

A woman in her 80s diagnosed as having Alzheimer’s disease, CDR: severe

The patient moved around in a reclining wheelchair and required total assistance. She was almost totally dependent for eating. Since she put her apron into her mouth, while she had food in her mouth, the food spilled out from her mouth. However, she did not look at the spilled food. When the author wiped her mouth with a wet towel, she tried to put the wet towel into her mouth. She also held a dry towel in her mouth after the meal.

Case 24

A woman in her 80s diagnosed as having vascular dementia, CDR: severe

The patient used a wheelchair to move around and required total assistance. She sat in the wheelchair, looking down and licking her fingers. She was totally dependent for eating. When a spoon was brought to her mouth, she opened her mouth, but she did not look at the spoon and kept looking ahead. In addition, she did not look at the spilled food.

Case 25

A woman in her 70s diagnosed as having dementia with Lewy bodies, CDR: severe

The patient moved around in a reclining wheelchair and required total assistance. She was totally dependent for eating. She scarcely looked at the caregiver or food during the meal. When food was put into her mouth, she mumbled a few times, but she often stopped eating with food in her mouth.

Case 26

A woman in her 80s diagnosed as having Alzheimer’s disease, CDR: severe

The patient used a reclining wheelchair to move around and required total assistance. She was totally dependent for eating. When a spoon was brought to her mouth, she opened her mouth, but she did not look at the caregiver. When food was put into her mouth, she mumbled, but she often stopped eating with food in her mouth.

Case 27

A woman in her 80 s diagnosed as having Alzheimer’s disease, CDR: severe

The patient used a reclining wheelchair to move around and required total assistance. She was totally dependent for eating. A caregiver brought a spoon to her mouth, but she very rarely opened her mouth. When food was put into her mouth using a little by force, she mumbled. However, once she had eaten about half the meal, she fell asleep with food in her mouth. When her body was shaken, she began to mumble again.

Case 28

A woman in her 70s diagnosed as having Alzheimer’s disease, CDR: severe

The patient moved around in a reclining wheelchair and required total assistance. She was totally dependent for eating. She did not look at the meal before her eyes, and even when a spoon was brought to her mouth, she very rarely opened her mouth. When a rice ball was put into her left hand, she brought it to her mouth by herself and ate the first bite. But after that, she scratched her head while holding the rice ball in the other hand.

Discussion

At this stage, the representation of the self was thought to be lost, and the test participants were thought to be unconscious of their bodies, situations, and behavior. Consciousness is to perceive objects as the participant, presupposing the presence of the self as the participant. ³⁶

The scenes in which the test participants mumbled a few times but stopped eating with food in their mouths after food had been placed in their mouths (cases 25 and 26) suggest that the participant was not conscious of his or her body, that is, intraoral organs such as the tongue. The reason for this lack of consciousness is thought to be that the object, that is, the food on the tongue, cannot be perceived through the senses of touch, proprioception, taste, or smell.

The scenes in which the test participants did not open their mouths although a spoon had been brought to their mouths (cases 20, 27, and 28), the scenes in which the test participants did not look at the meal before their eyes (scenes 24, 25, and 28), and the scenes in which the test participants did not look at spilled food (cases 23 and 24) suggest that the participant was not conscious of their own situation, that is, eating the meal. The reason for this lack of consciousness may be that the objects, that is, the food and the spoon before their eyes, cannot be perceived through their sense of sight.

The scenes in which the test participants put wet or dry towels or their aprons into their mouths and mumbled (cases 21, 22, and 23) and the scenes in which the test participants licked their fingers and empty plates (cases 19, 22, and 24) suggest that the participant was not conscious of their own behavior. The reason for this lack of consciousness may be that the objects, wet towels, aprons, fingers, and empty plates cannot be perceived through the senses of sight, taste, and smell.

Then, why do caregivers think that the words and deeds of people with dementia in eating actions are puzzling? As indicated by the words of a famous anthropologist, Reach, ³⁷ “food is a matter of language and culture, not a nature,” eating is not a simple physiological response, but is based on culture, such as what to eat, what not to eat, manners and taboos, integrated into the values of the country, region, race, religion, and era. Caregivers come to think that the words and deeds of people with dementia are puzzling, when the words and deeds of people with dementia deviate from the values of the caregivers in respect of the eating habits (food culture).

Participants who are unable to pass the task of theory of mind, but pass the task of self-evaluation can introspect on their situations to evaluate themselves in comparison with social standards and are able to maintain food culture. Therefore, caregivers do not think the words and deeds of such people with dementia as puzzling at this stage. However, people with dementia at this stage cannot presume others’ and their own minds, and caregivers will sometimes be bewildered by the egocentric words and deeds of people with dementia.

Participants unable to pass the task of self-evaluation cannot introspect on their eating situations to evaluate themselves in comparison with social standards, and therefore, the food culture that they have acquired collapses. Furthermore, since they become unable to introspect on their emotions, they become unable to control their emotions such as anger and fear. As a result, caregivers begin to think that the words and deeds of people with dementia as puzzling at this stage.

The participants unable to pass the task of self-consciousness not only cannot introspect on their eating situations but also cannot perceive through their senses. Therefore, caregivers further think that the words and deeds of people with dementia as puzzling and are bewildered while providing care.

The model in this article is based on the development of self-awareness in infants up to 4 to 5 years of age. Namely, this model deals with low-level self-awareness, and it is considered that no cultural differences will be observed in the results of evaluation of self-consciousness, self-evaluation, and theory of mind. With respect to the task of self-evaluation, if a task suitable for each culture is created following the procedure shown in this article, this model can be universally used in every country.

Human beings are able to live by adapting to a complex field of human relations only after acquiring the function to distinguish between the self and others (self-consciousness), the function to evaluate their thoughts and actions in comparison with the standards of the society in which they live (self-evaluation), and, finally, the function to presume others’ minds (theory of mind). In today’s evolutionary theory and primatology, the social intelligence (Machiavellian intelligence) hypothesis has been accepted, in which the evolution of “intelligence” was induced not because humans were tool manufacturers, but because it was necessary for humans to adapt to complex human relations, such as cooperation and diplomacy, with other individuals within the group to which they had come to belong. ^38,39 An approach based on the self-awareness ability, which is the ability to adapt to human relationships, is considered to be an appropriate and powerful method, in both evolutionary and primatological terms, for understanding the puzzling words and deeds spoken or performed by people with dementia with declining intelligence.

In the future, we shall further empirically investigate to what extent this model can explain the puzzling words and deeds of people with dementia.