Apathy is defined as lack of motivation that occurs in various neuropsychological disorders. Apathy frequently co-occurs in patients with late-life depression, and previous studies have shown that apathy is associated with frontal cognitive impairment that constitutes the distinct depressive syndrome in late-life depression. Here we tested elderly patients with mild to moderate depression on behavioral tasks requiring executive and non-executive functions.

The aim of this study was to examine that apathy, not depression, is associated with executive function in patients with late-life depression.

We enrolled 83 patients (67.9 ± 6.4 years of age; 51 women) with major depressive disorder from the geriatric psychiatric clinic of the Chang Gung Memorial Hospital. The inclusion criteria included a diagnosis of non-demented major depressive disorder. Patients with a history of any psychiatric disorders other than major depression, or major medical illness including neurological disorders such as Parkinson's disease, were also excluded. All participants were administered the 17-item Hamilton Depression Scale. The apathy-related items of the Ham-D are diminished work/interest, anergy, lack of insight, and psychomotor retardation.

We employed pairs of behavioral task to assess whether apathy has a distinct effect on executive control functions. Each test pair consisted of an executive and a non-executive task.

We showed that the extent of apathy significantly accounted for variances in performance in the frontal executive but not non-executive cognitive tasks.

These results extend previous studies by relating apathy to deficits in executive function in patients with late-life depression and suggest the importance of assessing the ‘apathetic syndrome’ in the clinical evaluation of patients with late-life depression