Aim: Recent magnetic resonance studies have demonstrated a higher decline with age in grey matter volume in man as compared to woman. On the other hand gender differences in regional cerebral blood flow studies have seldom been extensively taken into account. The aim of this study was to investigate by means of 99m-Tc-HMPAO and SPET the gender-related differences in rCBF in a large population of patients and normal controls.
Material and Methods: Forty-seven patients with Alzheimer Disease, 70 with Major Depression and 66 Controls were studied by 99m-Tc-HMPAO SPET. Radiopharmaceutical uptake was analysed by a standardisation software (CBA) automatically defining hemispheric (n=2) and cerebral lobes (n=10) outfits and calculating rCBF values. Group, gender and regional differences were assessed, after covariation for age, by analysis of co-variance (ANCOVA).
Results: There was no interaction between group and gender at any level and so we could consider the sex differences in all 183 subjects to be independent from groups. Gender accounted for significant differences at hemispheric (p<0.005) and cerebral lobes (0.001) level. At cerebral lobes level there was an overall interaction between gender and lobes (p<0.001) and more specifically gender differences were found in occipital (p<0.001), parietal (p<0.005) and temporal lobes (p<0.001). Significant interactions between sex and hemispheres were shown in frontal (p<0.05) and parietal (p<0.05) lobes. Overall right hemisphere and females had higher CBF than left hemisphere and males respectively.
Conclusions: Significant differences related to gender were found at hemispheric and cerebral lobes level. Females had a higher rCBF and there was a trend towards a least laterality. These findings suggest to perform an accurate gender matching when investigating group differences. Since gender influenced rCBF in frontal, parietal and temporal lobes particular attention should be paid in Alzheimer and Frontal Lobe Dementia studies.