Reduction of Cerebral Blood Flow in Older Depressed Patients

Background:  We investigated regional cerebral blood flow in older, drug-free depressed patients and examined factors that might be related to rCBF.

Methods:  We studied 39 physically healthy depressed patients over the age of 50 years and 20 psychiatrically healthy control subjects. Regional cerebral blood flow was measured with single photon emission computed tomography, using both xenon 133 (to quantify regional cerebral blood flow) and ^99mTc-hexamethylpropylene amine oxime (to make regional comparisons). From magnetic resonance imaging, we derived a semiquantitative measure of areas of white matter hyperintensity and a ventricle-to-brain ratio.

Results:  Patients exhibited a global reduction in regional cerebral blood flow compared with controls, with the orbital frontal and inferior temporal areas affected bilaterally. Regional cerebral blood flow was also reduced in higher brain slices in the right but not the left hemisphere. Significant predictors of lowered regional cerebral blood flow were being depressed, being male, and having a greater ventricle-to-brain ratio. There appeared to be a subgroup of patients who demonstrated large areas of white matter hyperintensity and low regional cerebral blood flow.

Conclusions:  Cerebral blood flow was lower in older, medication-free depressed patients than in agematched control subjects, involved the orbital frontal and anterior temporal regions, and was more reduced in the right hemisphere.