Is apathy a valid and meaningful symptom or syndrome in Parkinson's disease? A critical review.

Objective: To review the nearly 30 papers suggesting that apathy may occur frequently in Parkinson's disease (PD) and that it may be a symptom or syndrome that is separate from depression.

Method: Literature review.

Results: The review revealed three possible explanations for the high rates of apathy found in PD.

Living with Moebius syndrome: adjustment, social competence, and satisfaction with life.

Context: Moebius syndrome is a rare congenital condition that results in bilateral facial paralysis. Several studies have reported social interaction and adjustment problems in people with Moebius syndrome and other facial movement disorders, presumably resulting from lack of facial expression.

Objective: To determine whether adults with Moebius syndrome experience increased anxiety and depression and/or decreased social competence and satisfaction with life compared with people without facial movement disorders.

Facial mimicry is not necessary to recognize emotion: Facial expression recognition by people with Moebius syndrome.

According to the reverse simulation model of embodied simulation theory, we recognize others' emotions by subtly mimicking their expressions, which allows us to feel the corresponding emotion through facial feedback. Previous studies examining whether facial mimicry is necessary for facial expression recognition were limited by potentially distracting manipulations intended to artificially restrict facial mimicry or very small samples of people with facial paralysis. We addressed these limitations by collecting the largest sample to date of people with Moebius syndrome, a condition characterized by congenital bilateral facial paralysis.