Functional impairment in Virtual-Reality-Daily-Living-Activities as a defining feature of amnestic MCI: Cognitive and psychomotor correlates

Background: Early definitions of mild cognitive impairment (MCI) excluded the presence of functional impairment; instead, preservation of a person's ability to perform activities of daily living (ADL) was a diagnostic criterion. However, recent studies have reported varying degrees of functional impairment associated with MCI. Hence, we aimed to assess the potential functional impairment associated with MCI and its predictors by means of virtual reality. Methods: We assessed 71 healthy elderly subjects, 65 amnestic single-domain MCI subjects (a-MCI), 42 amnestic multi-domain MCI subjects (md-MCI) and 45 mild dementia of Alzheimer's type (mild-AD) subjects using Virtual Reality Activities of Daily Living (VR-ADL). VR-ADL focuses on the subtle errors and pattern in performing everyday activities and has the advantage of not depending on a subjective rating of an individual person. We further assessed functional capacity by both neuropsychological tests (including measures of attention, memory, working memory, executive functions, language, and depression) and also evaluated performance in finger-tapping, grip strength, stride length, gait speed and chair stands separately and while performing VR-ADLs in order to correlate performance in these measures with VR-ADLs. Usual gait speed is a valid and reliable indicator of physical performance, and predicts incident disability, hospitalization, institutionalization, falls, fractures and cognitive decline in elderly persons [1]. We hypothesize that the three cognitively impaired groups will have lower baseline cognitive, VR-ADL and upper-extremity function (UEF) and a greater reduction in performance in subsequent measurements than the cognitively healthy participants. Results: The md-MCI group was more impaired than the a-MCI group, and both were more impaired than healthy subjects in all VR-ADL measures. Also, the mild-AD was significantly more impaired than the MCI groups and healthy controls. Conclusions: Functional - mpairment is a defining characteristic of MCI and is partly dependent on the degree of cognitive impairment. Virtual Reality measures of functional ability seem more sensitive to functional impairment in MCI than qualitative measures. We conclude that VR-ADL is an effective tool for discriminating MCI and mild-AD from control and does so by detecting differences in terms of errors, omissions and perseverations while measuring ADL functional ability.