THURSDAY, June 20, 2024 (HealthDay News) — Cognitive impairment is delayed among persons who are heterozygous for the apolipoprotein E3 Christchurch variant (APOE3^Ch), according to a study published in the June 20 issue of the New England Journal of Medicine.

Yakeel T. Quiroz, Ph.D., from Massachusetts General Hospital in Boston, and colleagues analyzed data from 27 participants with one copy of the APOE3^Ch variant among 1,077 carriers of the PSEN1^E280A variant, which causes autosomal dominant Alzheimer disease, to estimate the age at onset of cognitive impairment and dementia.

The researchers found that the median age at onset of cognitive impairment was 52 years versus 47 years among carriers of PSEN1^E280A who were heterozygous for the APOE3^Ch variant compared with those without the APOE3^Ch variant. ¹⁸F-fluorodeoxyglucose positron-emission tomographic imaging in two participants with PSEN1^E280A and APOE3^Ch variants showed relatively preserved metabolic activity in areas typically involved in Alzheimer disease. In one participant, tau findings were limited compared with persons with PSEN1^E280A in whom cognitive impairment occurred at the typical age. Compared with autopsy material obtained from persons who had the PSEN1^E280A variant but not the APOE3^Ch variant, fewer vascular amyloid pathologic features were seen in persons with PSEN1^E280A and APOE3^Ch variants.

“The clinical, cognitive, neuroimaging, and neuropathological data that we present here provide evidence that APOE3^Ch heterozygosity delayed the onset of cognitive impairment in a form of autosomal dominant Alzheimer’s disease and may have a protective effect against Alzheimer’s disease and neurodegeneration in this population,” the authors write.

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