Patterns of brain activity in patients with epilepsy and depression

Depression is a recognized feature of epilepsy. This study tested the hypot hesis that depression arising in patients with epilepsy would be associated with decreased activity in brain regions previously demonstrated to be hyp operfused both in primary depression and in depression secondary to movemen t disorders. Two groups of patients with temporal lobe epilepsy were studie d, one of which also met DSM IV criteria for a major depressive episode. Al l underwent a SPECT scan using the blood flow marker, Tc-99m-HMPAO. An auto mated voxel-based analysis demonstrated no regions of relatively decreased activity in the depressed compared with the non-depressed patients. Sites o f relative hyperactivity in the depressed group were concentrated in the le ft hemisphere, particularly in dorsolateral prefrontal cortex, striatum, th alamus and temporo-parietal regions. Comparison of these data with normal p opulation data revealed that in the depressed epilepsy group regional activ ities were within the normal range whilst corresponding results from the no n-depressed group were below it. Depressed patients with epilepsy have cere bral regions with greater perfusion than non-depressed people with epilepsy , although they are not hyperperfused compared with normals. Our results su ggest that depression in people with epilepsy may arise from a mechanism wh ich differs from that underlying the development of depression in patients with movement disorders. (C) 1999 BEA Trading Ltd.