Apathy and related executive syndromes in dementia associated with Parkinson's disease and in Alzheimer's disease.

Apathy is defined as a lack of motivation and has been reported to be common in Alzheimer's disease (AD) and Parkinson's disease (PD). To explore the neuropsychological correlates of apathy in patients with PD related dementia (PDD) and AD and to identify the specific cognitive profile of apathy in the two forms of neurodegenerative disease, 61 non-depressed patients (29 PDD and 32 AD) were selected. Out of these, 29 patients (47.5%) were detected as apathetic (14 PDD-A+ and 15 AD-A+), and 32 patients as non-apathetic (15 PDD-A- and 17 AD-A-). All patients underwent cognitive tasks tapping memory, visuospatial and executive functions, behavioral rating scales and Clinical Judgment for Apathy Syndrome (CJ-AS), an inventory developed to measure severity of apathy. The four subgroups differed significantly on memory and frontal tasks. The PDD-A+ performed significantly worse than PDD-A- on frontal tasks. The AD-A+ had poorer performance than AD-A- on frontal tasks. Last, PDD-A+ achieved significantly higher scores than AD-A+ on memory tasks. The four groups differed significantly on CJ-AS and behavioral rating scales.The results showed that apathetic patients with both forms of dementia showed a common neuropsychological and behavioral picture, characterized by defects on frontal tasks, thus strongly supporting the existence of an 'apathetic syndrome', characterized by specific cognitive and psychological symptoms.