Vasoreactivity induced by acetazolamide in patients with vascular dementia versus Alzheimer's disease

Acetazolamide vasoreactive test measures the increment of cerebral blood flow caused by compensatory vasodilatation ability of cerebral vessels which can be detected by transcranial Doppler ultrasound (TCD). This study aimed to compare the vascular reactivity in patients with vascular dementia (VaD) and Alzheimer's disease (AD).

AD and VaD patients were recruited from the King Chulalongkorn Hospital Dementia Clinic. Thai Mini-mental State Examination was used for dementia detection. AD and possible VaD were defined by NINCDS/ADRDA and NINDS-AIREN criteria. Patients with extracranial carotid artery stenosis >50% and intracranial artery stenosis were excluded. TCD examination was performed using DWL Multi Dop-T. TCD was performed on MCA with insonation depth between 45 and 60 mm. Baseline end diastolic velocity (EDV), mid systolic velocity (MSV) and peak systolic velocity (PSV) were recorded. The velocities were obtained at 2, 5, 10 and 20 min after acetazolamide (1000 mg) injection. Mean baseline velocities (Vo) and velocities after acetazolamide injection (Va) were compared. Percentage of mean increment velocities was calculated {[(Va-Vo)/Vo]x100%}. Percentage differences of mean velocity change from Vo to Va at each recorded minute were compared. SPSS for Windows version 11.5.0. was used.

Nine AD (5 males) and 9 VaD (6 males) were selected. Average ages of VaD and AD groups were 66.11 years-old and 75.22 years-old respectively. Mini-mental State Examination (MMSE) score in VaD and AD were 21.13 and 19.00. Mean baseline EDV and MSV in VaD were higher than AD but mean PSV was lower. The percentage of velocity change after acetazolamide in AD was higher than VaD at 5, 10 and 20 min. However the differences were not statistically significant.

Acetazolamide vasoreactive test using TCD may be the additional criterion to differentiate VaD from AD. Further study with more number of subjects for the study or higher dose of acetazolamide may be needed to reveal the significant difference of vasoreactive response between VaD and AD patients.