[Noncognitive symptoms in Alzheimer's disease. A study of 150 community-dwelling patients using a questionnaire completed by the caregiver]

Abstract

We studied the noncognitive symptoms in 150 community-dwelling Alzheimer's patients using a questionnaire completed by the caregiver, the Echelle Psychopathologique de la Démence de Type Alzheimer, EPDTA (Psychopathologic Scale of Dementia of Alzheimer Type). EPDTA is a 44-item questionnaire derived from the BEHAVE-AD and the Depressive Mood Scale, covering many aspects of the behavior, affective and psychiatric disturbances. Each item is rated from 0 (never observed) to 6 (most of the time). Frequency (percentage of symptom present) and severity (mean score when the symptom was present) were assessed for each item. The cognitive status and severity of the disease were assessed by the MMSE and two scales completed by the caregiver assessing the Activities of Daily Living scale (ADL) and the Cognitive Difficulties Scale (CDS). Noncognitive symptoms were present in all patients but remained moderate in severity. A principal component analysis of the 33 items exploring the affective disturbances showed seven clinically relevant factors: apathy, anxiety, anosognosia-irritability, euphoria, dysphoria, emotional incontinence and agitation. The most frequent noncognitive symptoms were the affective disturbances, especially apathy, and the sexual behavioural disturbances. No correlation were found between the overall severity of behavioural disturbances and cognitive status, duration of the disease nor demographic variables. However, a slight negative correlation was found between scores on apathy and on the MMSE. A second evaluation was performed in 59 patients after a mean follow-up of 18,2 months. The patients showed a progression of the disease evidenced by the scores on the MMSE, ADL and CDS scales. However, the frequency and severity of the noncognitive symptoms remained identical except for eating disorders, psychotic symptoms and agitation which were more frequent at the second examination and negatively correlated with the MMSE score. Most patients showed affective disturbances and scored high for apathy and anxiety-emotional incontinence dimensions. Like in a previous study, we found a double dissociation between these two dimensions in some patients, suggesting that they depend from different mechanisms. Agressivity, mostly verbal, was found in three quarters of the patients and was correlated to apathy, anosognosia and psychotic symptoms.

Conclusion: The relationship between noncognitive manifestations and cognitive deficits in AD is not clear, suggesting that they depend from different biological and psychological mechanisms. Various dimensions may be described in the behavioural disturbances but their relationship with hypothetical biological mechanisms remains difficult. Our study stresses the importance of apathy, which was corelated with various noncognitive psychobehavioral manifestations in AD patients.