Preliminary findings of simultaneous F-18-FDG and Tc-99m-HMPAO SPECT in patients with depressive disorders at rest: differential correlates with ratings of anxiety

The assumption of a dynamic coupling between regional cerebral blood flow ( rCBF) and cerebral glucose metabolic rates (rCMRGlu) has been challenged by simultaneous measurements of both. Through the use of a dual-headed gamma camera with a 511-keV collimator applying the double isotope F-18-FDG and T c-99m-HMPAO SPECT technique, the uptake rates of these isotopes can be semi -quantitatively evaluated. Sixteen depressed patients, diagnosed by ICD-10 criteria and assessed with the 17-item Hamilton Rating Scale for Depression (HRSD), were studied. Based on the severity of HRSD-rated anxiety (item 10 : low = 1-21; high = 3-4), two eight-patient subgroups were formed and comp ared with 12 age- and handedness-matched healthy control subjects. As regio ns of interest, we selected areas implicated in the neuroanatomy of anxiety and depression: hippocampus (hippo), basal ganglia (BG) and gyri temporale s superiores (G.t.s.). In the control subjects, a significant statistical c oupling between rCBF and rCMRGlu was revealed by the Spearman correlation c oefficient only in left hippo and left BG. Patients in the low-anxiety subg roup demonstrated a marked dynamic coupling bilaterally for the G.t.s., whi le patients in the high-anxiety subgroup showed a significant statistical c orrelation of rCBF and rCMRGlu only in the left G.t.s. These findings indic ate that a dynamic coupling between blood flow and glucose metabolism exist s only in distinct brain regions, and that the depressive illness has an un coupling effect on this correlation in the left BG. Furthermore, our result s suggest that the HRSD anxiety score might interact with the underlying de pressive illness to influence the relationship of rCBF and rCMRGlu. (C) 200 0 Elsevier Science Ireland Ltd. All rights reserved.