Washington, June 10 : Studying an unusual case of a Dutch woman, who retained an essentially normal brain function until her death at the age of 115, experts have come to the conclusion that the assumption that Alzheimer's disease or other forms of dementia inevitably develop as the people age may not be true.

"Our observations suggest that, in contrast to general belief, the limits of human cognitive function may extend far beyond the range that is currently enjoyed by most individuals, and that improvements in preventing brain disorders of aging may yield substantial long-term benefits," according to a study led by Prof. dr. Gert Holstege of University Medical Centre Groningen, The Netherlands.

The researchers revealed that the woman had made necessary arrangements to donate her body to science after death, when she was 82.

Her body was donated to science when she died at age 115, they said.

"She was very enthusiastic about her being important for science," Holstege said.

He further said that his team found the patient to be "an alert and assertive lady, full of interest in the world around her, including national and international politics and sports."

He said that the research team’s key finding was the absence of brain abnormalities typical of Alzheimer's disease.

There were almost no deposits of a substance called beta-amyloid, which are characteristic of Alzheimer's patients, he added.

Holstege revealed that the subject had lived independently until moving to a residential care home at age 105, mainly because of poor eyesight. Ironically, she had been very small at birth and was not expected to survive.

He also revealed that a series of neurological and psychological examinations at the age of 112 and 113 showed that there were no signs of dementia or problems with memory or attention, and that her mental performance was above average for adults aged 60 to 75.

Apart from that, he added, the research group did not even find any evidence of atherosclerosis (narrowing of the arteries) in the subject’s body.

Holstege believes that this unique case lends new insights into the potential for preserving brain function in very elderly patients.

The findings appears in the August issue of Neurobiology of Aging. (ANI)