Table 1.

Conceptual boundaries for cognitive symptoms

Domain	Proposed reported symptom	Conceptual boundaries
		Includes	Excludes
Cognition	memory	Impairment of memory including difficulty remembering information; learning new information; orientation to time, place	the term “having to remember”
	concentration/attention	Difficulty concentrating or paying attention; sustaining focus
	cognitive slowing	Slowing or impairment of mental processing. Includes difficulty keeping up with conversations, slowness to respond, mental fatigue	confusion, ‘brain fog’, mental sharpness;
	language/word finding	difficulty understanding conversation; expressing oneself; difficulty speaking words that are being thought of. difficulty understanding what is being read/reading	difficulty understanding due to hearing impairment
	mental alertness/awareness	fluctuating alertness; fluctuations in/variable attention; zoning out, brain fog, confused thoughts, reduced mental sharpness	cognitive/mental slowing
	visuospatial abilities	difficulty judging distances or depth; navigating 3-dimensional situations; orienting oneself in space; identifying visual and spatial relationships among objects; trouble navigating closed or indoor spaces that are familiar	Freezing (interruption of gait) in doorways or thresholds.
	executive abilities/working memory	difficulty planning or executing tasks; multi-tasking; switching from one cognitive task to another, trouble following directions or instructions; problem solving; decision making; sequencing; learning new skills
	cognitive impairment NOS	Cognitive complaint not clearly fitting into another category. Could include confusion, muddled, mixed up