Prefrontal dysfunction in depressed patients performing a complex planning task: a study using positron emission tomography.
BACKGROUND
Patients with unipolar depression show impaired performance on the Tower of London planning task. Positron emission tomography, which has previously identified resting state blood flow abnormalities in depression, was used to investigate neural activity associated with performance of this task in depressed patients and normal controls.


METHODS
Six patients with unipolar depression and six matched controls were scanned while performing easy and hard Tower of London problems in a one-touch computerized paradigm and while performing a perceptuomotor control task.


RESULTS
The patients in this study showed an expected task-related performance deficit compared with normal subjects. In normal subjects, the task engaged a network of prefrontal cortex, anterior cingulate, posterior cortical areas and subcortical structures including the striatum, thalamus and cerebellum. Depressed patients failed to show significant activation in the cingulate and striatum; activation in the other prefrontal and posterior cortical regions was significantly attenuated relative to controls. Crucially, patients also failed to show the normal augmentation of activation in the caudate nucleus, anterior cingulate and right prefrontal cortex associated with increasing task difficulty.


CONCLUSIONS
These findings provide evidence for cingulate, prefrontal and striatal dysfunction associated with impaired task performance in depression. The present results are consistent with a central role of cingulate dysfunction in depression as well as suggesting impaired frontostriatal function.
Elliott
R
R
Wellcome Department of Cognitive Neurology, Hammersmith Hospital, University College London.
Baker
S C
SC
Rogers
R D
RD
O'Leary
D A
DA
Paykel
E S
ES
Frith
C D
CD
Dolan
R J
RJ
Sahakian
B J
BJ
D000328:Adult; D000704:Analysis of Variance; D016022:Case-Control Studies; D002560:Cerebrovascular Circulation / Q000502:physiology; D003342:Corpus Striatum / Q000000981:diagnostic imaging / Q000503:physiopathology*; D003866:Depressive Disorder / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000523:psychology; D005260:Female; D005625:Frontal Lobe / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006179:Gyrus Cinguli / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011340:Problem Solving / Q000502:physiology*; D014055:Tomography, Emission-Computed; D014836:Volition / Q000502:physiology*