Regional cerebral blood flow measurements in the diagnosis of dementia

The Xenon‐133 regional cerebral blood flow technique (rCBF) was used to assess cortical perfusion in a group of 15 elderly patients (mean age = 79.1, SD = 8.7) with a probable diagnosis of Dementia of the Alzheimer type (DAT). Nine had mild DAT and six were in the moderate stages of DAT. These patients were compared with 15 age and sex matched normal elderly controls (mean age = 75.1, SD = 5.6). RCBF was measured in each patient and control at rest with eyes closed. The DAT patients had significantly lower mean global CBF than normal controls (t = ‐4.63, p< 0,0001). In addition, a further 15 normal elderly subjects aged 60 to 92 were assessed and combined with the original 15 to allow calculation of a normal range of rCBF for elderly individuals. Seventy‐three per cent of the DAT patients fell below the lower limit of the normal range (39.3 ‐ 59.3 ISI units). These results show the possible usefulness of rCBF as an aid in the diagnosis of early DAT.