Prevalence of Hypoactivity and Apathy in Main Neurological Disorders
In a study  reporting the frequency of dysexecutive behavioral disorders observed in 280 patients referred in neuropsychology unit for cognitive concern, global hypoactivity with apathy was found to be the most frequent disorder: it was observed with frequencies roughly ranging from 20 % (stroke patients), 40 % (Parkinson’s disease and traumatic brain injury), and 60 % (Alzheimer’s disease). These frequencies are consistent with reviews focusing on apathy across brain diseases [30-33]. The present chapter details the characteristics of hypoactivity with apathy in major neurological diseases, Alzheimer’s disease, mild neurocognitive disorder, behavioral variant frontotemporal degeneration, Parkinson’s disease, and stroke.
Alzheimer’s Disease, Mild Neurocognitive Disorder, Behavioral Variant Frontotemporal Degeneration
Alzheimer’s Disease at the Major Neurocognitive Disorder Stage
In major neurocognitive disorders (i.e., dementia) caused by Alzheimer’s disease, behavioral dysexecutive syndrome (which includes hypoactivity with apathy) affects 86 % of patients . Hypoactivity with apathy is the most frequent behavioral disorder and is observed in between 30 and 85 % of patients [13, 34, 35]. This broad range of values is mainly due to differences in the clinical stage and the diagnostic criteria for Alzheimer’s disease. However, variability is also due to the disease subtype, since apathy is the most frequent behavioral manifestation of the recently characterized behavioral/dysexecutive variant of Alzheimer’s disease . Apathy in patients with Alzheimer’s disease is frequently associated with depression; in Starkstein’s study, 13 % of patients with Alzheimer’s disease presented with apathy and 24 % presented with a combination of apathy and depression . The characteristics and prognostic value of apathy in Alzheimer’s disease are subject to debate. Although apathy may appear in the early stages of dementia  and in the pre-dementia stage [38-41], the frequency increases with disease severity [35, 4244] . The presence of apathy has been linked to faster cognitive and functional decline [45, 46] and greater caregiver distress .