Apathy in Alzheimer's disease

In the last few years, a growing number of studies have been devoted to affective disturbances in Alzheimer disease, AD. These studies showed that apathy is a symptom clearly distinct from depression, and that confusion between apathy and depression appears to be one major cause of variability in the assessment of the frequency of depression in AD. We present the results of four studies from our group, devoted to affective disturbances in AD. These studies showed that apathy is a major symptom in AD which, usually, could be easily distinguished from depression. Apathy plays an important role for the early diagnosis of the disease, and is strongly correlated to impairment of daily living activities and to many psychobehavioral disturbances. Apathy is not a pathological entity, but a syndrome which could result from many different causes. On one hand it could be linked to brain lesions involving the cerebral regions underlying motivation. Different parts of the brain are involved in motivation, but their respective role remains ill defined according to the lack of a clear cognitive model of motivation. On the other hand, apathy can also be related to a psychological mechanism aimed to protect the patients from cognitive failures. We suggest that psychobehavioral manifestations in AD should be considered both from a biological point of view (primary symptoms mainly related to the location of brain lesions) and from a psychological point of view (secondary manifestations depending on the patients' and caregivers' reactions to the primary cognitive and affective symptoms of the disease). This distinction appears relevant to the care of the patient. In the first case, apathy hampers the management of the patient and should be fought against. In the second case, apathy is a psychological defense against major depression and should be managed with care.