Objective: To test the hypothesis that specific psychopathological non-cognitive symptoms are associated with incident mild cognitive impairment (MCI), while different symptoms are associated with incident dementia of Alzheimer's type (DAT).
Methods: A representative community sample of 4,803 individuals aged 55+ years was interviewed in a two-phase screening, in Wave I or ZARADEMP I. This is the baseline, cross-sectional study of the ZARADEMP Project, a longitudinal study to document incidence and risk factors of dementia. The main instrument for assessment of participants was the ZARADEMP Interview, which includes standardized Spanish versions of instruments such as the Mini-Mental Status Examination and the Geriatric Mental State GMS-AGECAT. Two years later, in Wave II or ZARADEMP II, the cognitively non-deteriorated elderly were reassessed in a similar, two-phase procedure. "Incident cases" of both dementia and DAT (DSM-IV-TR criteria), as well as MCI (operationally defined Petersen's criteria) were diagnosed by a panel of psychiatrists. Statistical, logistic regression models, adjusted by age, sex and education were used to test the hypothesized association.
Results: "Irritability", "neurovegetative symptoms", "sleep problems", "concentration difficulties", "loneliness" and "subjective slowing" documented at baseline were associated with incident MCI (odds ratio, OR range 1.71-2.67). A different profile of non-cognitive symptoms was associated with incident DAT, specifically "tension" (OR= 2.45), "sleep problems" (OR= 2.81), and "observed slowing" (OR= 4.35). On the contrary, "subjective restriction of activities" seemed to be negatively associated with DAT (OR= 0.12).
Conclusions: To our knowledge, this is the first report about some specific psychopathological, non-cognitive symptoms associated with incident MCI and/ or incident DAT, when controlling by each other. The psychopathological profile associated with MCI is different from the profile preceding DAT.