A prospective longitudinal study of apathy in Alzheimer's disease

Background: Apathy and depression are the most frequent behavioural and psychiatric disorders in Alzheimer's disease, and may both have a negative impact on the progression of the illness. Objectives: To examine the clinical correlates of apathy in Alzheimer's disease ( AD), and to determine whether apathy is a significant predictor of more rapid cognitive, functional and emotional decline. Methods: Using a structured psychiatric evaluation, we examined a consecutive series of 354 subjects meeting clinical criteria for AD. Apathy was assessed by the Apathy Scale, and diagnosed using standardised criteria. Additional measurements included scales for depression, functional impairment, and global cognitive functions. A follow up evaluation was carried out in 247 patients (70% of the total sample) between 1 and 4 years after the baseline evaluation. Results: Apathy was significantly associated with older age ( p = 0.009), and a higher frequency of minor and major depression ( p< 0.0001). Apathy at baseline was a significant predictor of depression at follow up ( p = 0.01), and was associated with a faster cognitive ( p = 0.0007) and functional decline ( p = 0.006). Conclusions: Apathy in AD is a behavioural marker of a more aggressive dementia, characterised by a faster progression of cognitive, functional, and emotional impairment.