New York, May 4 (IANS): An alteration in a gene may speed up the loss of memory and thinking skills in people who are already at the risk of Alzheimer's disease, according to a study.

According to researchers, people with Alzheimer's risk, who have the gene mutation called the BDNF Val66Met allele, or the Met allele may have a more rapid decline of memory and thinking skills.

Further, people with the gene mutation, who also had more beta-amyloid -- a sticky protein that can build up into plaques found in the brains of people with Alzheimer's disease -- had an even steeper rate of decline.

"Because this gene can be detected before the symptoms of Alzheimer's start, and because this presymptomatic phase is thought to be a critical period for treatments that could delay or prevent the disease, it could be a great target for early treatments," said Ozioma Okonkwo, from the University of Wisconsin in Madison, US. 

For the study, published in the journal Neurology, the team followed 1,023 people with an average age of 55 for up to 13 years who were at risk of Alzheimer's but were still healthy during the onset.

On tests of verbal learning and memory, those with no gene mutation improved by 0.002 units per year, while the scores of people with the mutation declined by 0.021 units per year.

This could be because, "when there is no mutation, it is possible the BDNF gene and the protein it produces are better able to be protective, thereby preserving memory and thinking skills", Okonkwo said.