Teenage IQ linked to risk of dementia

Jul 6 2005

Your IQ and extracurricular interests as a teenager may forecast your memory and thinking abilities decades later.

A new study by researchers at the University Memory and Aging Center, affiliated with Case Western Reserve University (Case) and University Hospitals of Cleveland (UHC), found that persons who were more active in high school and who had higher IQ scores, were less likely to have mild memory and thinking problems and dementia as older adults. Their results are published in the July 2005 issue of The Journal of the American Geriatrics Society.

Said Thomas Fritsch, Ph.D., the study's lead author, "We found that, controlling for gender and education level, higher adolescent IQ and greater activity level were each independently associated with a lower risk for dementia and mild cognitive impairments. Conversely, those who were lower on the IQ continuum and who participated in fewer activities in high school had a higher risk of cognitive impairments."

Dementia broadly refers to neurological conditions that cause decline in memory and thinking abilities (cognition) and the ability to perform activities of daily living. Alzheimer's disease (AD) is the most common cause of dementia in persons 65 years and older. According to estimates from the Alzheimer's Association, 4.5 million people have Alzheimer's nationally.

"The findings may help scientists in their efforts to understand the earliest roots of dementia," said Fritsch. "The knowledge gained from our research may also be useful to those who are developing models of AD. Such models might provide clues as to when it's best to try intervene with new therapies and treatments for persons with memory problems. The findings may also help those who are seeking ways to prevent the development of memory problems in adulthood."

The Case researchers used historical data from high school records and yearbooks from the mid-1940s to create a picture of the students' abilities and interests as teens. In 2002, interviews with the graduates, now in their 70s, and their family members were conducted to learn about the adult cognitive status of each subject. The research team reported on data collected from nearly 400 graduates.

"We found some very interesting associations between our early-life and late-life measures," said Fritsch. The article was written by Fritsch, an instructor of neurology at the Case School of Medicine and collaborators in the University Memory and Aging Center and at John Carroll University. The research was supported by grants from the NIH-NIA and the American Health Assistance Foundation.

A particular strength of the Case study is the use of objective measures of cognitive ability (IQ) collected in the teen years. Also, no study has yet reported on associations between teen activity levels and dementia risk using objective measures (i.e., extracurricular activity participation).

According to Fritsch, "Our findings confirm that markers for dementia risk can be found early in life. However, while our research implicates a role for IQ and activity level in youth, many other factors, alone or in combination, also influence who will and will not develop dementia. As we know, some very bright and active people develop dementia, while others who are less gifted and who were inactive as teenagers, do not. This indicates that the causes of dementia are complex and are determined by a host of factors."

According to the Case research team, it is premature to make lifestyle recommendations to teenagers based only on a single study. However, Fritsch commented, "It's a safe bet that being intellectually engaged, physically active, and socially connected has many health benefits across the lifespan and is to be recommended."