London, Nov 5 : New research shows that a rare brain disorder that causes early dementia is highly hereditary.

The brain disorder called frontotemporal dementia destroys parts of the brain, leading to dementia, including problems with language or changes in behaviour and personality. The disease often affects people under the age of 65, the website Science Daily reported.

"Knowing your family's health history may be one way for people to better predict their risk of developing dementia," said study author Jonathan Rohrer from University College London in Britain.

For the study, blood was drawn from 225 people who were diagnosed with frontotemporal dementia. The people were asked about family history of dementia and given a score of one through four. A score of one represents a person who had at least three relatives with dementia and an autosomal dominant inheritance, meaning that an affected person has one mutant gene and one normal gene and has a 50-percent chance of passing the mutant gene and therefore the disorder on to their offspring.

A score of four represents a person with no family history of dementia.

The study found that nearly 42 percent of participants scored between a one and a 3.5, meaning they had some family history of dementia. However, only 10 percent had an autosomal dominant gene history.

The people in the study also had their DNA tested for five gene mutations thought to cause frontotemporal dementia. Mutations were found in two of the five genes.

"Many people were still found to have a strong family history of dementia even without having any of the five known gene mutations, suggesting that there are still unknown genes that cause frontotemporal dementia," said Rohrer.

"Discovering new genes and gene mutations could provide another key to unlocking the doors to new treatments and prevention strategies for dementia."

The study also found that behavioural problems associated with frontotemporal dementia were most likely to be hereditary, while language problems were the least likely to be hereditary.

The study was published in the November issue of Neurology, the medical journal of the American Academy of Neurology.(IANS)