[Processing facial identity and emotional expression in normal aging and neurodegenerative diseases].

The ability to recognize facial identity and emotional facial expression is central to social relationships. This paper reviews studies concerning face recognition and emotional facial expression during normal aging as well as in neurodegenerative diseases occurring in the elderly. It focuses on Alzheimer's disease, frontotemporal and semantic dementia, and also Parkinson's disease. The results of studies on healthy elderly individuals show subtle alterations in the recognition of facial identity and emotional facial expression from the age of 50 years, and increasing after 70. Studies in neurodegenerative diseases show that - during their initial stages - face recognition and facial expression can be specifically affected. Little has been done to assess these difficulties in clinical practice. They could constitute a useful marker for differential diagnosis, especially for the clinical differentiation of Alzheimer's disease (AD) from frontotemporal dementia (FTD). Social difficulties and some behavioural problems observed in these patients may, at least partly, result from these deficits in face processing. Thus, it is important to specify the possible underlying anatomofunctional substrates of these deficits as well as to plan suitable remediation programs.