Background: Growing evidence suggests that pathological processes leading to Alzheimer’s
disease occurs gradually and begins to develop decades before the earliest clinical symptoms occur. The
use of biomarkers has been proposed to detect evidence of preclinical Alzheimer’s pathologic change in
asymptomatic subjects. Subjective cognitive complaints (SCC) i.e. self-reported cognitive decline with
normal cognition have been reported as an indicator of future cognitive decline, however, this condition
Objective: In the present study we used the regional brain perfusion measured by HMPAO-SPECT as
Biomarker of neurodegeneration to compare the regional brain perfusion of patient with subjective cognitive
complaints with and without minimal cognitive dysfunction (SCC+ and SCC- respectively) in respect
to patients with mild cognitive impairment (MCI).
Methods: We retrospectively examined 736 Patients who referred to our Memory Clinic because of suspected
cognitive dysfunction. After exclusion of patients with overt dementia, automated, quantitatively
assessed relative cerebral blood flow of 10 forebrain regions (thalamus, parietotemporal, medial temporal,
posterior temporal, posterior cingulate gyrus, each region left hemispheric and right hemispheric)
and neuropsychological assessment of 64 SCC (32 SCC+; 32 SCC-) and 28 MCI subjects were analysed.
Results:.The most relevant differences between groups in cognitive performance concerned verbal
memory. Left hemispheric medial temporal region could significantly discriminate between all three
groups, with a progressive decrease n perfusion from SCC towards MCI. Area under the curve of left
medial temporal region showed a sensitivity of 0,61 and a specificity of 0,78 for discriminating MCI
Conclusion: Automated analysis of HMPAO-SPECT data of MCI and SCC+ patients showed significant
perfusion differences in medial temporal region and impaired verbal memory, both of which are
known features of Alzheimer’s disease. Perfusion patterns and verbal memory performance in SCC+ are
more similar to MCI than SCC-.
Thus, SPECT analysis could distinguish those subjects whose perfusion pattern resembles that of an
MCI from those who do not. In our opinion, this could identify two populations with a different risk of
progression to AD, with SCC+ subjects needing further diagnostic examination and repeated follow-up.