Impairment of Attention and Executive Functions in Cerebrovascular Cognitive Impairments and Alzheimer's Disease.

Objectives. To establish the specific features of impairments to executive functions (EF) and attention at the initial stages of vascular cognitive impairment (VCI) and Alzheimer's disease (AD). Materials and methods. A total of 80 patients aged over 50 years with VCI or AD, as well as 29 healthy volunteers (control group), took part in the study. Cognitive functions were assessed using the following tests: the Mini-Mental State Examination (MMSE), the Montreal Cognitive Assessment Scale (MoCA), the Executive Function Interview Technique (EXIT-25), the Frontal Assessment Battery (FAB), the clock drawing test, the 12-word memory test, the verbal association test (literal and categorical), the trail-making test (TMT A and B), the symbol-digit substitution test (SDST), the Stroop test, and Benton's visual memory test. A mandatory criterion for inclusion in the study was availability of a brain MRI scan in T1, T2, FLAIR, DWI, and SWI modes acquired during year preceding recruitment. Results. The AD and VCI groups were comparable in age, gender, education, and the severity of CI. Impairments in attention and EF were noted in both VCI and AD and were somewhat more marked in AD. Qualitative analysis of the individual components of EF showed that the VCI and AD groups had comparable impairments in cognitive control as compared with the control group, while AD was characterized by a more significant decrease in intellectual flexibility than VCI. Concentration of attention was affected equally in patients with VCI and AD; differences from the control group were significant (p < 0.05). In the memory domain, auditory-verbal and semantic memory were found to suffer to a much greater extent in AD, while both conditions were characterized by identical involvement of the visual modality. Conclusions. Impairments to attention and EF are not specific to the subcortical type of CI. AD even in its early stages is characterized by significant impairments to attention and EF, while the EF component intellectual flexibility suffers to a greater extent at the onset of AD than VCI. Memory impairments are not specific to AD; visual memory impairment comparable to AD is noted as early as the onset stage of VCI. These data can be used for early neuropsychological diagnostics and the differential diagnosis of CI. [ABSTRACT FROM AUTHOR]