Alzheimer's disease, traditionally considered an old person's illness, may be present in healthy young adults.
A study published online in the journal Neurology
found structural differences in the brains of people who have a geneitc risk of developing Alzheimer's disease.
A team of neuroscientists examined the associations between aggregate genetic risk and Alzheimer's disease markers prior to clinical symptoms of dementia using data from the International Genomics of Alzheimer's Project. They calculated a polygenic risk score in 166 people with dementia and 1,206 without dementia. Participants were an average of 75 years old.
Researchers also looked at links between the risk score and hippocampus volume in 1,322 healthy, younger participants between the ages of 18 and 35.
They found that for older people without dementia, a higher polygeneic risk score was associated with worse memory and smaller hippocampus at the start of the study. For younger adults, a higher risk score was tied to smaller hippocampus volume. The findings suggest that signs of Alzheimer's risk may manifest decades earlier than previously thought.
"The influence of this genetic risk may begin in early life and make an individual more suxceptible to cognivive imparment in late life," the study authors write. "Future refinement of polygenic risk scores may help identify individuals at risk for Alzheimer's disease."