FULL RANGE OF VASODILATION TESTED BY TRANSCRANIAL DOPPLER IN THE DIFFERENTIAL-DIAGNOSIS OF VASCULAR AND ALZHEIMER TYPES OF DEMENTIA

The aim of this study is to validate whether measuring the cerebral va somotor response with the breath-holding method can be a useful techni que in the differentiation of vascular and Alzheimer types of dementia . We adopted the clinical and neuropsychological diagnosis of dementia according to DSM-IV criteria as the standard diagnosis against which our method was compared. Resting middle cerebral artery velocity, its rate of increase on breath holding and its decrease on hyperventilatio n (full range of vasodilation, FRV) were measured using a transcranial Doppler (TCD) velocimeter on both sides in a prospective study on 32 age-matched controls, 36 patients diagnosed with Alzheimer type dement ia, and 31 vascular dementia (VD) patients. a total of 186 vessels wer e studied in 99 patients. A high level of significance (p < 0.001) was noted in the FRV in the differentiation between the VD group and the other two groups, on both sides and in both sexes. By taking a statist ically optimal cutoff point of 70%, the sensitivity and specificity of the FRV test for the diagnosis of VD are 84.5 and 93.0% respectively. Measurements of hemodynamic reserve using the cerebral perfusion rese rve test assessed by TCD could provide a way to detect demented indivi duals with underlying vascular mechanism of dementia, but would not of fer prognostic data or differentiate between varying degrees of dement ia.