Acetazolamide vasoreactivity in vascular dementia: A positron emission tomographic study

The present study investigates the vasoreactivity of the brain in patients with large infarcts and dementia (multiinfarct dementia; MID) and in patien ts with microangiopathy, lacunes, white matter changes a nd dementia (lacun ar dementia; LD) using positron emission tomography (PET) and (NH3)-N-13 as regional cerebral blood flow (rCBF) tracer. In the control group, an incre ase in rCBF ranging from 32 to 43% was found in all brain regions after int ravenous acetazolamide administration. In both the MID group and the group with multiple infarcts without dementia, moderate loss of vasoreactivity wa s observed in the frontal, temporal and parietal cortex compared to the con trol values. Vasoreactivity was severely impaired in all cerebral regions o f the LD group and restricted to the thalamus in the group with lacunes and white matter changes without dementia (lacunar stroke; LS), This suggests that global loss of vasoreactivity is not a determining factor in the occur rence of MID, but might be important in LD, The present study shows that lo ss of the vascular reserve leading to exhausted metabolic reserve of the wh ole brain is one of the possible mechanisms for the occurrence of vascular dementia.