Washington, Mar 11 : Offspring of patients having Alzheimer's disease might be more susceptible to developing the condition, say researchers at University of Washington, Seattle.
The study, led by Suman Jayadev, M.D., of the University of Washington, Seattle, has stated that Alzheimer's disease is hereditary and identifying genes in patients can help detect others who are at risk for the condition.
"Because Alzheimer's disease is so common in the general population, it is not uncommon for both spouses to develop the disease. Offspring of two such affected individuals would presumably carry a higher burden of these Alzheimer's disease-associated genes," states the background information in the study.
For the study, the researchers examined the frequency of Alzheimer's disease in adult children of 111 families in which both parents had been clinically diagnosed with the disease. They also noted down the ages at onset of dementia.
It was found that among 297 offspring who reached adulthood, 22.6 pct developed Alzheimer's disease in comparison to an estimated 6 pct to 13 pct of the general population.
The results also indicated that the average age at onset for children of couples with the illness was 66.3. The risk of developing the disease increased with age with 31 percent of those older than age 60 affected and 41.8 pct of those older than age 70 affected.
"Of the 240 unaffected individuals, 189 (78.8 percent) had not yet reached age 70 years, suggesting that the incidence of Alzheimer's disease (22.6 percent) is an underestimation of the final incidence rate of Alzheimer's disease in this population," wrote the authors.
However, having extra family members with Alzheimer's disease did not increase the risk of developing the disease, but was associated with a younger age at onset for those who did develop the illness.
The researchers discovered that children with no history of the disease beyond the parents had an older age at onset (72 years) compared with those who had one parent with family history of the disease (60 years) or both parents with family history of the illness (57 years).
"The role of family history and the specific genes involved in this phenomenon require a better definition. Families with a significant Alzheimer's disease history may be more likely to be referred to an Alzheimer's disease research center and, thus, the present patients may be 'enriched' for a particularly Alzheimer's disease-prone subgroup. Following these families as the offspring continue to age will provide increasingly informative data," concluded the authors.
The study is published in the latest issue of Archives of Neurology, one of the JAMA/Archives journals.