The British Journal of Psychiatry
Cognitive impairments in patients with seasonal affective disorder.
J T O'Brien, B J Sahakian, S A Checkley


Eleven patients with seasonal affective disorder (SAD) and ten controls matched for age, IQ, and education were tested on a number of computerised tests designed to assess attention, memory, and learning. When depressed, patients showed no deficit in attention but were impaired on spatial memory and learning. They were also significantly slower to respond than controls, with a pattern that suggested slowed information processing centrally, rather than simple sensory or motor slowing. On recovery from depression, improvement was seen in most tests, although impairment remained in latency to respond on a test of spatial memory. This continuing impairment correlated with residual depressive symptoms but not with ventricular brain ratio (VBR).