SPECT patterns in probable Alzheimer's disease

The primary objective of this study was to test hypotheses about the relati onship between HMPAO-SPECT findings and probable Alzheimer's disease (DAT) in a relatively large sample of patients diagnosed according to DSM-III-R. SPECT patterns of 20 controls and 116 DAT patients were investigated. Left and right frontal, temporal, parietal and occipital regions of the brain we re rated as showing a hypoperfusion or not. A wide variety of patterns were found and these are described in detail below. In DAT patients, temporal a nd/or parietal regions were affected significantly more often (88%, p > 0.0 01) than frontal and/or occipital regions (70%). A bilateral temporoparieta l pattern, which has been repeatedly reported as typical for DAT, was obser ved in 48% of DAT patients, but also in 25% of controls, and did not differ entiate significantly between these two groups (p > 0.05). Conversely, more than three regions with hypoperfusion were observed significantly more oft en in DAT patients (48%, p < 0.01) than in controls (10%). In DAT patients, the number of regions with hypoperfusion correlated significantly with the score of the Mini Mental State Examination (MMSE, r = 0.33, p < 0.001). Th e frequency of at least one hypoperfusion was approximately equal in left a nd right hemispheres (77% vs. 73%, p = 0.2). The hypothesis that cognitive decline in DAT starts in the temporal regions was tested in 14 SPECT patter ns showing only one region with hypoperfusion. In 12 of these patterns, a t emporal region was in fact affected (p < 0.001). Whereas hypoperfusion in f rontal areas was not accompanied by a significantly lower MMSE than when on ly temporoparietal regions were affected, MMSE scores were significantly lo wer when occipital regions were affected in addition to temporoparietal reg ions (p < 0.05). The clinical use of SPECT findings was tested in discrimin ating analyses with the MMSE and a delayed recall test as additional predic tors of DAT. Whereas the MMSE and the delayed recall test differentiated si gnificantly between DAT patients and controls, SPECT findings yielded no fu rther differentiation. In conclusion, the theoretical and clinical implicat ions of SPECT findings and their relationships to other physiological and p sychological variables deserve further investigation.