SPECT in Alzheimer's disease: features associated with bilateral parietotemporal hypoperfusion

Objective - To investigate why bilateral parietotemporal hypoperfusion, the typical SPECT pattern of Alzheimer's disease (AD), occurs in some but not in all patients with probable AD. Methods - We reviewed the SPECT scans of 220 patients presenting with cognitive impairment Among them, 104 patients fulfilled NINCDS-ADRDA criteria for probable AD, 48 (32 women) with early o nset (before age of 65) and 56 (40 women) with late onset of the symptoms. Dementia severity was assessed by the Mini-Mental State Examination. The SP ECT scans were classified by visual inspection blind to clinical diagnoses. Results Bilateral parietotemporal hypoperfusion was more frequent in patie nts with severe AD, in those with early onset of the symptoms, and in men. Duration of symptoms, type of gamma-camera or radiopharmaceutical agent use d were not associated with this SPECT pattern. Conclusion These findings ma y be useful in the clinical setting and point to heterogeneity of AD accord ing to age at onset.