Apathy in frontotemporal dementia and Alzheimer's disease: are there distinct profiles?

Objective: To find out if distinct clinical profiles of apathy can be distinguished in frontotemporal dementia (FTD) and Alzheimer's disease (AD). Subjects: 13 outpatients with the frontal variant of DFT, 36 with AD and 29 control subjects. Methods: The scores of the Apathy evaluation scale, AES (Marin), filled in by close relatives, were compared to a) cognitives measures, including global ratings (Mini mental state, Dementia rating scale), and specific assessments for memory (Selective reminding test), inhibition (Stroop test) and planification (6 elements); b) affective measures for depression (Montgomery and Asberg, and Hamilton depression rating scales), emotional disturbances (Abrams and Taylor scale, ATS; Depression mood scale, DMS), assessment of valence and intensity of affective reactions by the International affective picture system, IAPS), dimensions of personality (NEO PI-R, Defensive style questionnaire, DSQ); c) functional assessment: Self-maintenance physical scale (ADL) and Instrumental activities of daily living (Lawton), Social activities scale (Katz and Lyerly), and Disability assessement for dementia, DAD. Apathy was also assessed by the Neuropsychiatric Inventory (NPI) and a new tool, the Goal-directed activities scale (GDAS), which allows a quantitative assessment of 32 goal-directed activities and a qualitative evaluation of 4 causal attributions: E = related to external factors; M = disease related; C = affective disturbance related; and D = lack of motivation. Results: A close relationship was found between AES scores and global cognitive deficits in FTD and AD, but only in AD for the memory and executive tests. No relationship was found with the depression scales or dimensions of personality. A significant relationship was found both in FDT and AD with blunted affect as assessed by ATS, but not with direct assessment by the DMS or reactions to the IAPS. Functional activities were closely related to AES scores in all evaluations, except for ADL score in FTD. Causal attributions were mainly related to lack of motivation in FTD (60% of cases according to the patients, and 85% according to the spouses), and both to affective disturbances (respectively in 36 and 48% of cases) and lack of motivation (33% and 45%) in AD. Conclusion: No distinct cognitive or emotional profiles of apathy could be found in FTD and AD. Apathy was constant, more severe, and mainly related to lack of motivation in FTD, less constant, less severe in AD, and related both to affective disturbances and lack of motivation.