Cognitive function in middle-aged and older adults participating in synchronized swimming-exercise

Abstract

[Purpose] The purpose of the present study was to examine cognitive function in middle-aged and older adults regularly engaging in synchronized swimming-exercise. [Subjects and Methods] Twenty-three female synchronized swimmers ranging in age from 49 to 85 years were recruited for the present study. The duration of synchronized swimming experience ranged from 1 to 39 years. The control group consisted of 36 age- and gender-matched community-dwelling middle-aged and older adults (age range: 49 to 77 years). Cognitive function was evaluated using the Japanese version of the Montreal Cognitive Assessment (MoCA-J) and compared between the synchronized swimmers and control participants. [Results] No significant differences in mean total MoCA-J scores were observed between the synchronized swimmers and control participants (23.2 ± 3.1 and 22.2 ± 3.6, respectively). Twenty-nine subjects in the control group and 17 in the synchronized swimming group scored below 26 on the MoCA-J, indicative of mild cognitive impairment. Significant differences in delayed recall—but not in visuospatial/executive function, naming, attention, language, abstraction, or orientation—were also observed between the two groups. [Conclusion] The results of the present study suggest that synchronized swimming has beneficial effects on cognitive function, particularly with regard to recent memory.

INTRODUCTION

The number of older adults affected by dementia has been rising significantly in Japan and a number of other countries^{1, 2)}. Mild cognitive impairment (MCI)^3,4,5,6) is considered to be a preclinical stage of dementia. Studies have revealed that approximately 10% to 15% of people with MCI progressed to dementia annually^7,8,9). In order to reduce the number of people who experience cognitive dysfunction, it is important to delay, or even reverse, the progression of MCI to dementia. Dementia is common in individuals of advanced age. While aging is regarded as the greatest risk factor for cognitive dysfunction¹⁰⁾, several studies have indicated that habitual exercise and physical activity may have a beneficial effect on the prevention of dementia^{11,12,13,14,15)}.

A wide variety of exercises, such as walking, have been recommended for older adults in efforts to maintain and promote health. Aquatic exercises in particular are recommended for older adults with obesity and osteoarthritis^16,17,18). One such aquatic exercise regimen is synchronized swimming, which is suitable for older adults, as the swimmer may stand on the floor of a shallow pool¹⁹⁾.

While a number of studies have indicated that land-based exercise exerts a beneficial effect on cognitive function in older adults^11,12,13,14), no studies to date have examined the effect of synchronized swimming on cognitive function in older adults. We examined cognitive function in middle-aged and elderly synchronized swimmers.

SUBJECTS AND METHODS

The study participants were recruited from among 23 women practicing synchronized swimming-exercise at a sport club in Fukushima-ku, Osaka City, Japan (SS group). All participants provided written informed consent, after having gained a full understanding of the present study. The study was approved by the ethics committee of the Osaka University of Health and Sport Sciences (approval number 15-21).

Synchronized swimming was performed in a shallow pool from 1.2 to 1.3 meters in depth and the participants were allowed to touch the bottom of the pool with their hands and feet during the performance. Participants who had participated in the Olympic Games or the domestic competitions for seniors were excluded. Participants practiced synchronized swimming twice a week for 90 minutes under the supervision of an instructor, who had been a member of the Japanese synchronized swimming team. The ages of participants in the SS group ranged from 49 to 85 years (mean age: 69.8 ± 11.6 years), and the duration of synchronized swimming experience ranged from 1 to 39 years (mean year: 23.9 ± 12.6 years).

Control participants were recruited age-matching women with exercise custom other than synchronized swimming. They were 36 individuals participating in a health promotion program at our university in 2015, and provided written informed consent as controls (age range: 49–77 years; mean age: 67.0 ± 6.0 years). Among the participants in the control group, 16 participants exercised three or four times a week, 17 exercised once or twice a week, and 3 exercised one to three times a month. In addition, three participants engaged in aquatic exercises other than synchronized swimming.

Cognitive functions was compared between the two groups using the Japanese version of the Montreal Cognitive Assessment (MoCA-J)²⁰⁾. The MoCA is a brief cognitive test containing test items related to memory, language, executive function, working memory (attention), visuospatial recognition, abstract thinking, and orientation²¹⁾. The sensitivity and specificity of the MoCA-J in screening for MCI has been demonstrated²⁰⁾. The assessment takes only approximately 10 minutes to complete, and a number of studies have demonstrated the effectiveness of MoCA-J as a screening tool for MCI^21,22,23). The maximum MoCA-J score is 30. Total scores of less than 26 points may be indicative of mild cognitive impairment.

Information on the presence of neurological disease, psychiatric disease, alcoholism, and hospitalization was collected via an interview. None of the participants in either group exhibited any such history.

Results are expressed as the mean ± SD. Unpaired t-tests were used to compare results between the SS group and control group when data were normally distributed, while U tests were performed when the data were not normally distributed. Two-sided p values of <0.05 were considered to indicate a statistically significant difference. Statistical analyses were performed using SPSS Statistics ver. 23.0.

RESULTS

No significant differences in education level were observed between the control and SS groups (12.1 ± 2.0 and 12.2 ± 1.8 years, respectively). In addition, no significant differences in total MoCA-J scores were observed between the two groups (22.2 ± 3.6 and 23.2 ± 3.1, respectively). Twenty-nine participants in the control group and 17 in the SS group scored below 26 on the MoCA-J and were suspected of having MCI (Table 1). With regard to MoCA-J sub-scores, significant differences in delayed recall (p=0.005) were noted between the two groups. However, no significant differences were observed with regard to measures of but not in visuospatial/executive function, naming, attention, language, abstraction, or orientation (Table 2).

Table 1. Comparison of MoCA-J between the control group and the SS group.

	Score	Control group (n=36)	SS group (n=23)
MoCA-J	<26	29 (80.6)	17 (73.9)
	≥26	7 (19.4)	6 (26.1)

No significant differences are shown between the two groups. Unit: number, (): percent. MoCA-J: Japanese version of Montreal cognitive assessment; SS: synchronized swimming

Table 2. Comparison of MoCA-J sub-score between the control group and the SS group.

	Control group (n=36)	SS group (n=23)
Visuospatial/executive function (5)	3.5 ± 1.0	3.4 ± 1.0/5
Naming (3)	2.9 ± 0.4	3.0 ± 0.0
Attention (6)	4.9 ± 1.1	4.8 ± 1.0
Language (2)	1.6 ± 0.9	1.7 ± 0.8
Abstraction (2)	1.1 ± 0.8	0.9 ± 0.7
Delayed recall* (5)	1.8 ± 1.7	3.0 ± 1.4
Orientation (6)	5.8 ± 0.4	5.6 ± 0.7
Total scores	22.2 ± 3.6	23.2 ± 3.1

Values are shown as the mean ± SD. *p<0.005 for the difference between the two groups. SS: synchronized swimming. (): full score

DISCUSSION

No significant differences in years of education or total MoCA-J scores were observed between the SS group and the control group in the present study. The results of total MoCA-J scores in the present study align with those of a previous report involving 1,552 participants (mean age: 72 years; Mini-Mental State Examination score >24 points) living in Sasaguri, Fukuoka Prefecture, in which mean the MoCA-J score was 22.4 ± 3.0²⁴⁾. However, in the comparison of MoCA-J sub-score in the present study, delayed recall scores, which are considered indicative of recent memory function, were significantly higher in the SS group than in the control group.

Suzuki et al.²⁵⁾ conducted an exercise-based intervention program that included exercise, calculation, word-chain game, and multiple tasks using a ladder diagram program (90 minutes two times per week for 6 months) with participants aged 65 years or older experiencing MCI. Significant differences in Mini-Mental State Examination, Wechsler Memory Scale-Logical Memory I, Word Fluency Test-category, and Word Fluency Test-letter scores were observed following this intervention. In synchronized swimming, participants must swim and act in a coordinated manner with other swimmers while performing to music. In other words, the swimmers are required to perform multiple coordinated tasks in an aquatic setting to be more complex than those of the multicomponent exercise program developed by Suzuki et al²⁵⁾. We speculated engaging in those tasks exerted positive effects on memory function. Moreover, it has been reported that group music intervention delayed the deterioration of cognitive function, particularly short-term recall among aging adults with mild and moderate dementia²⁶⁾. Performing to music in synchronized swimming might be one of the reason that delayed recall scores were significantly higher in the SS group than in the control group.

Voelcker-Rehage et al.²²⁾ reported that not only physical fitness, as indexed by cardiovascular fitness and muscular strength, but also aspects of motor fitness, such as movement speed, balance, motor coordination, and flexibility exhibit associations with executive control and perceptual speed. They further demonstrated physical and motor fitness to be differentially related to various cognitive processes using functional brain magnetic resonance imaging. Given that most synchronized swimmers exhibit good cardiopulmonary function, muscle strength, and flexibility²⁷⁾, it is also possible that enhanced physical fitness may exert direct positive effect on cognitive function.

According to a report by Suzuki et al.²⁸⁾, 12 months of multicomponent exercise significantly improved cognitive function in older adults with amnestic MCI. In particular, positive effects were observed for general cognitive function, immediate memory, and language ability. We therefore consider that synchronized swimming exerted beneficial effects on cognitive function in the participant who experienced synchronized swimming for one year.

In conclusion, the results of the present study suggest that synchronized swimming may improve cognitive function in older adults, particularly with regard to recent memory.

Conflict of interest

No relevant disclosures.