TEMPORAL-LOBE ABNORMALITIES IN DEMENTIA AND DEPRESSION - A STUDY USING HIGH-RESOLUTION SINGLE-PHOTON EMISSION TOMOGRAPHY AND MAGNETIC-RESONANCE-IMAGING

Objectives-Perfusion SPECT and MRI were used to test the hypothesis th at late onset depression is associated with brain abnormalities. Metho ds-Forty depressed patients (DSM-III-R major depressive episode, not d emented at two year follow up) were recruited who were either drug fre e, or on a stable dose of antidepressants for at least three weeks, as well as 22 demented patients (DSM-IIIR and NINCDS/ADRDA criteria for probable Alzheimer's disease). Patients were imaged at rest with a hig h resolution single slice 12 detector head scanner (SME-Neuro 900) and the cerebral perfusion marker Tc-99m-exametazime (HM-PAO). Temporal l obe templates were fitted with brains pitched by 20 degrees-30 degrees . A subgroup of 41 patients (22 depressed) were also scanned using a S iemens Magnetron 1.0 Tesla magnetic resonance imager, using a FLAIR im aging sequence for the assessment of white matter hyperintensities, an d a Turbo FLASH sequence for the measurement of medial temporal lobe w idth. Results-Demented patients showed reduced perfusion, particularly in the left temporoparietal cortex. In these regions of interest, pat ients with late onset depression tended to have perfusion values inter mediate between patients with early onset depression and demented pati ents. Differences in changes in white matter between demented and earl y and late onset depressive patients did not reach conventional levels of significance. Temporal lobe width differed between demented and de pressed patients, but not between early and late onset depressed patie nts. Perfusion and temporal lobe width were not associated, but reduct ions of perfusion were associated with periventricular white matter ch anges. Mini mental state examination scores were associated with tempo ral perfusion in demented patients and with changes in deep white matt er in depressed patients. Finally, severity of depressive symptoms was associated with decreased perfusion in frontotemporal and basal gangl ia regions of interest. Conclusion-A cumulative effect of duration of illness on regional cerebral perfusion could not be confirmed. Late on set depression may show more abnormalities of deep white matter and of left temporoparietal perfusion than early onset depression, but the u nderlying pathology remains to be established.