Symptoms of apathy are associated with progression from mild cognitive impairment to Alzheimer's disease in non-depressed subjects

Background: Apathy is a common symptom in various neuropsychiatric diseases including mild cognitive impairment (MCI) and dementia. Apathy may be associated with an increased risk of cognitive decline. The objective of this study was to investigate if apathy predicts the progression from MCI to Alzheimer’s disease (AD). Methods: The Alzheimer’s Disease Neuroimaging Initiative is a prospective multicentre cohort study. At baseline, 397 patients with MCI without major depression were included. Clinical data and the Geriatric Depression Scale at baseline were used. Apathy was defined based on the 3 apathy items of the 15-item Geriatric Depression Scale. The main outcome measure was the association of apathy with progression from MCI to AD. Results: During an average follow-up of 2.7 years (SD 1.0), 166 (41.8%) patients progressed to AD. The presence of symptoms of apathy without symptoms of depressive affect increased the risk of progression from MCI to AD (hazard ratio = 1.85, 95% CI = 1.09-3.15). Apathy in the context of symptoms of depressive affect or symptoms of depressive affect alone, without apathy, did not increase the risk of progression to AD. Conclusions: Symptoms of apathy, but not symptoms of depressive affect, increase the risk of progression from MCI to AD. Apathy in the context of symptoms of depressive affect does not increase this risk. Symptoms of apathy and depression have differential effects on cognitive decline.