A longitudinal study examining the independence of apathy and depression after stroke: the Sydney Stroke Study.

Background: There is growing recognition that apathy is not only a symptom of depression but may be an independent syndrome. This is the first study to investigate the relationship of apathy and depression longitudinally following stroke and to examine the association with dementia.

Method: 106 consecutive eligible participants following stroke received extensive medical, psychiatric and neuropsychological assessments at three to six months (index assessment) and 15 months (follow-up assessment) after their stroke. A subset of participants received magnetic resonance imaging (MRI) scans at index assessment. Ratings were made for DSM-IV major or minor depression and for apathy using the Apathy Evaluation Scale (AES).

Results: While there was no significant overlap between apathy and depression at index assessment (OR = 1.79, 95% CI 0.48, 6.66), the overlap was significant a year later (OR = 7.75, 95% CI 2.60, 23.13). Dementia at index assessment was a common risk factor for both apathy and depression at follow-up (OR = 12.45, 95% CI 2.98, 52.02 and OR = 10.35, 95% CI 2.84, 37.72, respectively).

Conclusions: Apathy and depression after stroke have a common predictor and overlap longitudinally. The overlap might be due to cumulative vascular pathology and because of the relationship of each of these syndromes to dementia, which was an important, possibly causal, predictor for both.