Response to tacrine in patients with dementia of the Alzheimer's type: Cerebral perfusion change is related to change in mental status

We evaluated change in cerebral hypoperfusion by single photon emission computed tomography (SPECT) in 12 patients with a clinical diagnosis of dementia Alzheimer's type (DAT) before and after treatment with Tacrine. Based on clinical evaluation of the SPECT scans before and after treatment, two groups of patients were identified. One (N = 5) experienced a relative decrease in cerebral perfusion and a decrease in mini-mental status examination (MMSE) scores across the treatment interval and was labled "non-responders." A second group consisting of 7 patients was judged as showing an increase in cerebral perfusion at follow-up compared to baseline and an increase in MMSE scores. These were termed "responders". The group difference in MMSE score change was significant (Fisher's exact test: p < 0.008). Sensitivity (0.85) and specificity (1.0) and Receiver Operating Characteristic values (discriminability or d' = 3.12 and bias or beta = 4.6) indicated that direction of change in cerebral perfusion was a reasonable indicator of direction of change in MMSE scores. These results suggest that SPECT determined changes in cerebral perfusion may be useful in identification of DAT patients who are more likely to respond to centrally active agents such as tacrine.