High striatal amyloid beta-peptide deposition across different autosomal Alzheimer disease mutation types.

BACKGROUND

Supported by compelling genetic data regarding early-onset familial Alzheimer disease (AD), the amyloid beta-peptide (Abeta)-centric theory holds that Abeta is involved in the pathogenesis of sporadic AD. Mutations in the amyloid precursor protein (APP), presenilin 1 (PSEN1), and presenilin 2 (PSEN2) genes lead to increased Abeta levels before symptoms arise.

OBJECTIVES

To evaluate the pattern of Pittsburgh Compound B (PiB) retention in subjects with different autosomal dominant mutations associated with familial AD vs that in healthy age-matched control subjects and subjects with probable sporadic AD, to correlate Abeta burden as measured by PiB with available clinical and cognitive data, and to compare the regional brain patterns of PiB retention and fluorodeoxyglucose F 18 (FDG) uptake.

DESIGN

Correlation analysis of positron emission tomography (PET) imaging studies.

SETTING

Academic research.

PARTICIPANTS

Seven PSEN1 mutation carriers and 1 APP mutation carrier underwent PiB and FDG PET imaging. Amyloid beta-peptide burden and FDG uptake were established using standardized uptake values normalized to pons.

MAIN OUTCOME MEASURE: Primary outcomes were PET results, which were compared with those of a well-characterized cohort of 30 healthy control subjects and 30 subjects with probable sporadic AD.

RESULTS

All mutation carriers had high PiB retention in the striatum, with some also having cortical PiB retention in ventrofrontal and posterior cingulate/precuneus areas. The striatal pattern of PiB retention was similar in the PSEN1 and APP mutation carriers. Neither striatal nor cortical Abeta burden was related to cognitive status.

CONCLUSIONS

Consistent with previous studies, the pattern of Abeta deposition in familial AD differs from that in sporadic AD, with higher striatal and somewhat lower cortical PiB retention in familial AD. The pattern and degree of Abeta deposition were not associated with mutation type nor cognitive status.