. Author manuscript; available in PMC: 2023 Jun 1.

Published in final edited form as: Lancet Neurol. 2022 Apr 14;21(6):537–550. doi: 10.1016/S1474-4422(21)00422-1

Table 3.

Diagnostic criteria for Persistent Postural Perceptual Dizziness (PPPD) and Functional Cognitive Disorder

Persistent Postural Perceptual Dizziness Bárány Society diagnostic criteria	Functional Cognitive Disorder proposed diagnostic criteria⁴
One or more symptoms of dizziness, unsteadiness or nonspinning vertigo on most days for at least 3 months. Symptoms last for prolonged (hours-long) periods of time but may wax and wane in severity. Symptoms need not be present continuously throughout the entire day. Persistent symptoms occur without specific provocation, but are exacerbated by three factors: upright posture, active or passive motion without regard to direction or position, and exposure to moving visual stimuli or complex visual patterns. The disorder is triggered by events that cause vertigo, unsteadiness, dizziness, or problems with balance, including acute, episodic or chronic vestibular syndromes, other neurological or medical illnesses, and psychological distress. When triggered by an acute or episodic precipitant, symptoms settle into the pattern of criterion A as the precipitant resolves, but may occur intermittently at first, and then consolidate into a persistent course. When triggered by a chronic precipitant, symptoms may develop slowly at first and worsen gradually. Symptoms cause significant distress or functional impairment. Symptoms are not better accounted for by another disease or disorder.	One or more symptoms of impaired cognitive function. Clinical evidence of internal inconsistency The ability to perform a task well in a particular cognitive domain at certain times, but with significantly impaired ability demonstrated in the same domain, particularly when the task is the focus of attention. Not simply fluctuation over time. Consider red flags for other cognitive disorders which may present with features of inconsistency or fluctuation^* Symptoms or deficit that are not better explained by another medical or psychiatric disorder, although comorbid disorders allowed. Symptoms or deficit that cause clinically significant distress or impairment in social, occupational, or other important areas of functioning, or warrants medical evaluation

Persistent Postural Perceptual Dizziness
Bárány Society diagnostic criteria

Functional Cognitive Disorder
proposed diagnostic criteria⁴

One or more symptoms of dizziness, unsteadiness or nonspinning vertigo on most days for at least 3 months.
1. Symptoms last for prolonged (hours-long) periods of time but may wax and wane in severity.
2. Symptoms need not be present continuously throughout the entire day.
Persistent symptoms occur without specific provocation, but are exacerbated by three factors: upright posture, active or passive motion without regard to direction or position, and exposure to moving visual stimuli or complex visual patterns.
The disorder is triggered by events that cause vertigo, unsteadiness, dizziness, or problems with balance, including acute, episodic or chronic vestibular syndromes, other neurological or medical illnesses, and psychological distress.
1. When triggered by an acute or episodic precipitant, symptoms settle into the pattern of criterion A as the precipitant resolves, but may occur intermittently at first, and then consolidate into a persistent course.
2. When triggered by a chronic precipitant, symptoms may develop slowly at first and worsen gradually.
Symptoms cause significant distress or functional impairment.
Symptoms are not better accounted for by another disease or disorder.

One or more symptoms of impaired cognitive function.
Clinical evidence of internal inconsistency
1. The ability to perform a task well in a particular cognitive domain at certain times, but with significantly impaired ability demonstrated in the same domain, particularly when the task is the focus of attention.
2. Not simply fluctuation over time.
3. Consider red flags for other cognitive disorders which may present with features of inconsistency or fluctuation^*
Symptoms or deficit that are not better explained by another medical or psychiatric disorder, although comorbid disorders allowed.
Symptoms or deficit that cause clinically significant distress or impairment in social, occupational, or other important areas of functioning, or warrants medical evaluation

”Red Flags” discussed in the source document⁴ included: 1) Inconsistency between cognitive domains – e.g. impaired single word vs sentence comprehension in semantic dementia, difficulties relating to visual comprehension (such as posterior cortical atrophy) that can produce effects similar to internal inconsistency, e.g. the reverse size effect, effects of apathy or low mood, intact implicit memory with defective conscious memory (e.g. Korsakoff’s); 2) Variability over time can occur in other disorders such as Lewy Body Dementia, delirium and obstructive sleep apnoea.