New research illustrates that when it comes to risk of Alzheimer’s disease, even genetically determined forms of this disease, genetics is only one piece of the puzzle.
“Presence of the e4 allele of the APOE gene is associated with increased risk for developing sporadic Alzheimer’s disease and an earlier age of clinical onset than for individuals without an e4 allele,” said Massachusetts General Hospital clinical neuropsychologist Dr. Yakeel Quiroz and colleagues.
“However, evidence for an effect of APOE e4 genotype on cognitive function in autosomal dominant Alzheimer’s disease (ADAD) has been limited and inconclusive.”
“ADAD is genetically determined by mutations on the amyloid precursor protein, Presenilin-1 (PSEN1), and Presenilin-2 (PSEN2) genes,” they added.
“The largest known kindred with ADAD due to a single mutation (PSEN1 E280A) resides in Antioquia, Colombia.”
“Carriers of this mutation have a median age of onset of mild cognitive impairment at 44 years and of dementia at 49 years.”
In their new study, the authors investigated the influence of genetics and educational attainment on cognitive decline by studying data from 675 people (370 female, 305 male) who carry the PSEN1 E280A mutation.
They found that among carriers who also carried a second mutation that puts them at heightened risk, APOE e4, had an accelerated age of onset of cognitive decline.
Among carriers who had an APOE e2 mutation — known to be protective — age of onset was delayed.
The researchers also assessed the effect of educational attainment on cognitive function among PSEN1 E280A mutation carriers, including those who carried different APOE genotypes.
They found that higher educational attainment — that is, more years of education — was associated with preserved cognitive ability particularly for those at highest genetic risk.
“Higher educational attainment may have a protective effect against cognitive impairment, even in the presence of…
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