Twin studies have been carried out to extend current understanding of the genetic risks of suffering from Alzheimer's.
Scientists believe that results from the most extensive twin study ever carried out may help them to assess the factors which most influence the onset of the disease and therefore lead to the development of preventative measures.
Using the Swedish Twin Registry, researchers looked at 11,884 twin pairs aged 65 years and over. Out of these, 392 of the pairs had at least one member suffering from Alzheimer's.
The study found that identical twins were more likely to have the disease than non-identical and that genetics seems to play a role in when the condition becomes active.
Researchers used statistical analysis to estimate the significance of genetic factors, concluding that the risk of developing Alzheimer's was 80 per cent genetic.
The study, published in the Archives of General Psychiatry, said that non-genetic factors are also important and that research into environmental influences would help to develop therapies to limit or delay the onset of symptoms.