Cognitive evaluation in cerebral small vessel disease: towards an evidence-based identification of the reference standards. Part 1. A systematic review and qualitative data synthesis

Background Cerebral small vessel disease (cSVD) is a leading cause of cognitive impairment in the elderly. Despite cSVD cognitive profile is thought to be mainly characterized by attention and executive functions deficits, there is no definite agreement on the standards for its evaluation. This systematic review aims at identifying cognitive domains and neuropsychological tools specifically chosen in the assessment of cognitive impairment related to cSVD, and the temporal and geographic trends in their utilization. Methods Following PRISMA guidelines, original articles focused on cSVD patient samples neuropsychologically evaluated were searched using PubMed, Scopus and PsycINFO databases without language or time restrictions (PROSPERO registration number CRD42018089882; date 27-02-2018). Results We screened 13,688 studies and included 298 in the qualitative data synthesis. Global cognitive functioning and attention/executive functions were the most evaluated domains (87% and 69%, respectively). Mini Mental State Examination was the most used screening tool (73%), followed by MoCA (14%) whose utilization rapidly increased over the last years. The most frequently used second level tests were phonemic and semantic fluencies (39% and 30%, respectively), Trail Making Test (TMT) part A and B (31% and 32%, respectively), Stroop (31.5%), and Boston naming (30%). All tests resulted stably utilized over time, except for semantic fluency and Stroop whose use increased. Phonemic fluency and Boston naming were the most used in North America (51% and 45%, respectively), TMT in Europe (43%), and Stroop and semantic fluency in Asia (43% and 40%, respectively). Conclusions This systematic review confirms that attention/executive functions domain is the most commonly evaluated in cSVD together with lexical retrieval abilities based on executive control processes. Temporal and geographic variability emerged in the choice of tests. PROSPERO registration number CRD42018089882 (27-02-2018).