Preclinical evidence of Alzheimer changes in progressive mild cognitive impairment: a qualitative and quantitative SPECT study

Objectives: Baseline brain single-photon emission computed tomography (SPECT) can predict mild cognitive impairment (MCI) patients at risk for progressive MCI (PMCI). Methods: Twenty-eight subjects [12 MCI, 6 with probable Alzheimer's Disease (AD), and 10 normal subjects] underwent baseline brain SPECT and were clinically followed for a mean period of 36 months. Results: Of 12 MCI patients, 6 progressed to PMCI and 6 remained stable. Baseline SPECT identified asymmetric perfusion reduction in the parahippocampus (-5%), lateral parietal (-8%), and posterior cingulate (-11%) cortices - reductions consistent with that of mild AD - in five of the six PMCI patients. Significant perfusion reduction was observed particularly in the frontal cortices of probable AD when compared with PMCI (P < 0.05). Conclusion: Baseline SPECT can identify brain perfusion abnormalities among patients with MCI for progression to PMCI. This imaging modality may aid in MCI treatment stratification.