Genetic factors important in Alzheimer's disease

Reported by Susan Aldridge, PhD, medical journalist

A twin study concludes that genetic factors are strong in Alzheimer's disease.
As the population ages, the number of cases of Alzheimer's disease is set to increase, so it has never been more important to understand the underlying causes of the disease. A team at the University of Southern California has sought to shed new light on genetic factors by looking at Alzheimer's disease among twins.

Known genetic risk factors account for a small percentage of cases but it is thought the genetic influence goes wider than this. In this new study, using the Swedish Twin Registry, nearly 12,000 pairs of twins were investigated and 392 pairs where one or both had Alzheimer's were identified. They concluded that heritability was between 58 and 79 per cent.

The findings also suggested that genetic factors affect the timing of the disease. In identical twins, the difference in age at onset was around four years, for non-identical twins it was more like eight years. The nature of the genes underlying the incidence of Alzheimer's in twins is unknown. But this is the largest twin study to date and will form the basis for further investigations.

Source
Archives of General Psychiatry February 2006 Volume 63 pages 168-174

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