Non drug treatments such as mental training and physical activity may help cure dementia, a disorder characterised by a general loss of intellectual abilities , says a new study.

Researchers led by Sally A. Shumaker at Wake Forest University School of Medicine studied about 3,000 participants. Half of them received 10 sessions of cognitive training and half received no special training, reported the health portal Medical News Today.

Participants who had the training showed immediate improvement in memory, reasoning and speed of processing. When the participants were tested five years later, the improvements had been sustained, the study said.

There are an estimated 24 million people in the world with dementia and 4.6 million new cases are diagnosed each year.

"Cognitive decline is a rapidly growing problem because of our aging population," Shumaker said.

"The latest research suggests that mental training and physical activity both have promise for preventing declines in cognition," the researcher said in the Journal of the American Medical Association.

"It's possible to envision a future treatment approach that combines lifestyle and drug treatments to meet the specific needs of each individual," she said.