British scientists have identified a new gene that they claim is linked to late-onset Alzheimer's disease.

Alzheimer's disease is a common form of dementia - a brain disorder that impairs memory and judgment ability.

Late-onset Alzheimer's is a type of Alzheimer's that affects one in 10 people over 65 years of age and half of the people over 85 years of age, reported website.

Researchers from 15 institutions including London's Institute of Neurology analysed the DNA of 1,411 people and found the gene GAB2 influenced the risk of dementia among those with Alzheimer's gene APOE4.

GAB2 appears to modify the effects of APOE4. In turn, this leads to the formation of the characteristic protein tangles found in the brains of people with Alzheimer's, the researchers said in the medical journal Neuron .

"This impressive research suggests a common gene could be responsible for a four-fold increase in risk of developing Alzheimer's disease," said Clive Ballard, director of research at the Alzheimer's Society.

"It is the most important risk factor gene to be identified in relation to tangles, which develop in the brain in Alzheimer's disease," he added.