Cerebral vascular transit time in Alzheimer's disease and Korsakoff's psychosis and its relation to cognitive function.

The cerebral vascular transit time of 17 patients with pre-senile dementia of the Alzheimer type (ATD), nine abstinent patients with alcoholic Korsakoff's psychosis (KOR), and ten age-matched controls was determined by the bolus intravenous injection of pertechnetate. A gamma camera was used to estimate the median transit time (MTT) of the radioactive bolus in a planar (non-tomographic) projection normal to the vertex. The spread of the bolus arriving at the aortic arch was measured independently by a single external detector over the chest, and correction made for the transit time of this input function in calculating the net MTT for the head. Both ATD and KOR groups showed lengthened net MTTs, compatible with reduced cerebral blood flow, and which were correlated with reduced cognitive function. It is concluded that the method employed gives a simple, inexpensive estimate of function-related blood flow to the brain in pre-senile dementia.