Washington, Apr 5 (IANS): A person's memory deteriorates at a faster rate in the last two-and-a-half years of his or her life than at any other time after memory problems first begin, says a study.

Conversely, keeping mentally fit through reading of other mental activity may be the best way to preserve memory during late life. Both these studies were conducted by researchers at Rush University Medical Centre, Chicago.

"In our first study, we used the end of life as a reference point for research on memory decline rather than birth or the start of the study," said study author Robert S. Wilson, neuropsychologist at Rush Medical Centre in Chicago, the journal Neurology reported.

For the study, 174 Catholic priests, nuns and monks without memory problems had their memory tested yearly for six to 15 years before death. After death, scientists examined their brains for hallmarks of Alzheimer's disease called plaques and tangles, said a university statement.

The study found that at an average of about two-and-a-half years before death, different memory and thinking abilities tended to decline together at rates that were eight to 17 times faster than before this terminal period.

The second study, also conducted by Wilson, showed that keeping mentally fit through board games or reading may be the best way to preserve memory during late life.

The study, which focused on mental activities, involved 1,076 people with an average age of 80 who were free of dementia. Participants underwent yearly memory exams for about five years.

They reported how often they read the newspaper, wrote letters, visited a library and played board games such as chess or checkers. Frequency of these mental activities was rated on a scale of one to five, one meaning once a year or less and five representing every day or almost every day.

"The results suggest a cause and effect relationship: that being mentally active leads to better cognitive health in old age," said Wilson.