Cognitive and functional decline and neuropsychiatric symptoms in mild cognitive disorders

Objective: Mild cognitive impairment (MCI) is seen as a preclinical stage of Alzheimer's dementia, as it is associated with an increased risk of developing dementia. In dementia, cognitive functioning, activities of daily living (ADL) and neuropsychiatric symptoms (NPS) are extensively investigated. Only a few studies on these domains are conducted in MCI. Furthermore, limitations in ADL are traditionally measured on the level of instrumental (i-) ADL, while in MCI, more subtle changes in advanced (a-) ADL, high level activities, might appear before i-ADL declines. Basing a diagnosis of MCI solely on cognition and i-ADL results in many false positives and negatives. Current study explores the presence of and the relationship between cognition, ADL and NPS in cognitive healthy controls, MCI and AD. MethodsFifty cognitive healthy controls (mean age 79.5 ±5.1), forty-eight patients with MCI (mean age 80.4 ±4.7), and forty-five patients with mild AD (mean age=80.7 ±5.1) were recruited in two university Geriatric Day Hospitals. Participants were evaluated with the Mini Mental State Examination, the Cambridge Examination for Mental Disorders of the Elderly, the Neuropsychiatric Inventory Questionnaire (except for the cognitive healthy controls, due to the absent of a proxy) and the a-ADL tool. ResultsSignificant differences were observed between the three groups for cognitive measurements and a-ADL . Surprisingly, the presence of NPS in MCI and AD is, except delusions and aberrant motor behaviour, not significantly different. When looking for the correlations between the three domains, for the sample as a whole, significant correlations were found between: a-ADL and cognition (-.171<r<-.665; p<.05); a-ADL and NPS (.285<r<.296; p<.01); cognition and NPS (r=.221; p<.01). For the groups separately, a more diffuse pattern with less significant correlations was found. ConclusionNPS and cognitive and functional decline, measured on a-ADL level, might constitute important signs of MCI. To diagnose MCI, it is important to use a battery of relevant tests, based on cognition, a-ADL and NPS. Longitudinal research is needed to determine the usefulness of these three domains for prediction of conversion of MCI to dementia.