Assessment of cognitive fluctuation in dementia: a systematic review of the literature

Objective: Cognitive fluctuations (CF) are defined as spontaneous alterations in cognition, attention and arousal. They are a recognised feature of the dementias, especially dementia with Lewy bodies (DLB) and Parkinson's disease dementia. However, the accurate identification and assessment of CF presents a major clinical difficulty, with the operationalisation of the term 'cognitive fluctuation' remaining elusive, despite several attempts to identify, quantify and assess the phenomenon. No published reviews of CF in dementia exist despite this being an important clinical phenomenon and a core diagnostic feature of DLB.

Methods: We systematically explored the literature and measures available for the definition, assessment and quantification of CF in the dementias.

Results: We identified only three psychometric measures, which have been developed for the identification and assessment of CF, and these have not been adequately tested as yet for reliability and validity.

Discussion and conclusions: We conclude that further research is warranted into the assessment of CF, and this is timely given the increasing recognition of the clinical importance of CF as a dementia symptom, particularly in the Lewy body dementias.