Global Hypoactivity and Apathy
Résumé
Global hypoactivity contrasting with apparently unaffected cognitive abilities was initially reported in cases of frontal damage and is now recognized as a leading behavioral feature of many cerebral diseases. Of the various terms used to refer to this behavioral change, ``apathy'' is now the most widely used. Global hypoactivity with apathy is easy to diagnose in patients without other obvious neuropsychiatric impairments. In other clinical contexts, the diagnosis of global hypoactivity with apathy requires the physician to first establish that hypoactivity and loss of motivation cannot be more readily explained by sensorimotor impairments (e.g., as observed in patients with stroke or Parkinson's disease) or cognitive impairments (e.g., as observed in patients with Alzheimer's disease). Many criteria and behavioral scales have been used to diagnose hypoactivity with apathy. The main differential diagnosis is depression and depressive symptoms, and distinguishing between these conditions and apathy may be particularly challenging. The mechanisms of hypoactivity with apathy remain uncertain and probably involve several dysfunctions, including the inability to attach motivational values to stimuli. We reviewed the frequency, characteristics, and determinants of hypoactivity with apathy in Alzheimer's disease, frontotemporal lobar degeneration, Parkinson's disease, and stroke, across the different stages of cognitive compromise. The diagnosis of this condition is an important step in identifying the source of difficulties in patients' activities of daily living.