Apathy is defined as a lack of motivation in behaviour, cognition and affect. The aim of this article is to evaluate, in Alzheimer's disease (AD), the frequency of apathy and its relations with depressive symptoms and neuroanatomical correlates. We present the results of 3 French studies: the evaluation of behavioural symptoms in 499 AD subjects; the evaluation of depression and apathy in 128 AD subjects; a single photon computed tomography study (SPECT) performed in 31 AD subjects.