Scheinin NM, Aalto S, Kaprio J, Koskenvuo M, Raiha I, Rokka J, Hinkka-Yli-Salomaki S, Rinne JO.
Early detection of Alzheimer's. 11C-PIB PET in monozygotic and dizygotic twins discordant for cognitive impairment.
Human Amyloid Imaging 2011 Meeting Abstracts. 2011 Jan 15;
Background: The relative impacts of genetic and environmental factors are still unknown for sporadic, late-onset
Alzheimer's disease. The importance of genetic factors with regard to beta-amyloid (As) accumulation in the
brain is therefore of great interest. Knowledge of As accumulation in cognitively healthy individuals could improve
our understanding of the pathology of Alzheimer's disease and allow its early detection. Carbon-11 labeled
2-(4f-methylaminophenyl)-6-hydroxybenzothiazole i.e. 11C-PIB is a PET imaging agent applicable for in vivo As
plaque detection, and it was used as a marker of As accumulation also in this study.
Subjects and methods: We performed a 11C-PIB PET study on 9 monozygotic and 8 dizygotic twin pairs
discordant for cognitive impairment as well as on 9 healthy elderly control subjects. 11C-PIB uptake was analyzed
with Statistical Parametric Mapping (SPM) and with region-of-interest (ROI) analysis with the region-to-cerebellum
ratio as a measure of tracer uptake.
Results: Cognitively preserved monozygotic co-twins of cognitively impaired probands had increased cortical
11C-PIB uptake (117-121% of control mean) in their temporal and parietal cortices and the posterior cingulate.
Cognitively preserved dizygotic subjects did not differ from the controls (uptake 96-103% of control mean). Further,
the cognitively preserved monozygotic subjects showed similar 11C-PIB uptake patterns as their cognitively
impaired co-twins. The cognitively impaired subjects (monozygotic and dizygotic individuals combined) showed
typical Alzheimer-like patterns of 11C-PIB uptake.
Conclusions: Genetic factors appear to influence the development of Alzheimer-like As plaque pathology.
Alzheimer's disease may be detectable in high-risk individuals in its presymptomatic stage with 11C-PIB PET, but
clinical follow-up will be needed to confirm this. This would have important consequences for future diagnostics
and research on disease-modifying treatments.
Keywords: Alzheimer's disease, early detection, PIB, PET, twin.