Family history of Alzheimer’s doubles risk

Relatives of people with Alzheimer’s disease are more than twice as likely to develop abnormal brain pathology associated with the condition compared with individuals who don’t have a family history of the disease, a recent study said. The findings were posted April 17 in the online journal PLOS ONE.

Researchers found that 47% of cognitively normal people who had a partner or sibling with the neurodegenerative disorder met criteria for preclinical Alzheimer’s disease based on measurements of their cerebrospinal fluid. But only 21% of cognitively normal participants without a family history of the disease met such criteria, the study said.

Researchers found that a variation in the APOE e4 gene was overrepresented in participants with a family history of Alzheimer’s disease, the study said. That particular gene is associated with an increased risk and earlier onset of the neurodegenerative condition. But other biological differences also were detected in those with a family history, suggesting that unidentified genetic factors might influence the diseases’s development before the onset of dementia, the study authors said (link).

Researchers examined data from 257 adults, age 55 to 89, who were part of the Alzheimer’s Disease Neuroimaging Initiative, a national study working to define the progression of Alzheimer’s through biomarkers. Some participants in the PLOS ONE study were cognitively healthy while others had varying levels of cognitive impairment.

Researchers examined participants’ age, gender and family history of the disease. A positive family history was defined as ever having a parent or sibling with the condition. That information was compared with cognitive assessments and other biological tests, including APOE genotyping and magnetic resonance imaging scans measuring hippocampal volume.