Genes May Be Key to Long, Dementia-Free Life

Elderly who still think clearly may have their genes to thank, a new study says.

Aug. 16, 2012— -- Ralph Light has a garden. For years, he has been growing beans, strawberries, sweet corn, wheat, asparagus and tomatoes for his neighbors and family.

It's a hard hobby at any age -- but for Light, who is 94 years old, the work is an exceptional testament to his physical and mental health.

"We raised what we ate for years," says Ralph. "We used to can hundreds of quarts" of fruits and vegetables.

Light, who lives with his wife of 68 years, is also an avid reader, with a fondness for detective novels. He reads two or three of them every week.

And the only question that seems to stump him is what the secret is to his spry nature.

"I've kept active," Light says.

On Wednesday, a study published online in the journal Neurology shows some evidence that protection from dementia clusters in families. In other words, those like Light may have their genes to thank for their healthy minds.

Indeed, Light seems to be cut from long-lived stock.

"I had four brothers… almost all who lived in to their 90s," Light says. "None of them had dementia."

What's more enticing to the rest of us -- who may or may not be so genetically gifted -- is that learning more about the genes in Light's family and other like it may be the key that will one day help protect the rest of us from dementia.

Lead investigator Jeremy M. Silverman, a professor in the department of psychiatry at the Mount Sinai School of Medicine, and his colleagues examined 277 male veterans, aged 75 and older, who were free of dementia symptoms. They conducted blood tests to measure levels of a substance called C-reactive protein in the men's blood. Since high levels of C-reactive protein tend to correspond to high levels of dementia in younger elderly patients, some assume those elderly patients with high levels of C-reactive protein who do not develop dementia are somehow resistant to cognitive decline.

The researchers then interviewed 1,329 of the test subjects' relatives to assess their rates of dementia. What they found was that the rates of dementia in the families of patients who exhibited resistance was lower than the rate seen in families of patients who did not show resistance.

To validate these findings further, investigators repeated the study with an older group of 51 patients and surveyed 202 of their relatives. This group returned the same results. In both study populations, patients with resistance to dementia were over 30 percent less likely to have relatives with dementia.

Since C-reactive protein is not always linked to dementia, the conclusions drawn should be met with a critical eye.

"[Dementia] is a very complicated disorder, and the findings in a study like this need to be reproduced in other studies before they are going to be transformative," says Dr. Eric Larson, vice president for research at the Group Health Research Institute based in Seattle.

Still, while the study does not show exactly what is protective in these men, it offers some tantalizing possibilities for future investigation. Silverman's group is already examining the genes of other patients who seem to be protected from dementia and taking note of similarities.

"This study provides one more piece of evidence that 'the cure' may be staring at us from the faces of these survivors, if we could only make out specifically what it was," says Richard Caselli, professor of neurology at the Mayo Clinic in Scottsdale, Ariz. "It also gives us further reason to be optimistic that a cure is not impossible... nature seems to have already found a way."

However, until this genetic link can be established conclusively, doctors say there are still cues that everyone can take from people like Ralph Light.

"Mr. Light's family likely has a good genetic profile plus a lifetime of physical activity and is not overweight or a smoker. And he is engaged in life," says Dr. John Messmer, an associate professor of family and community medicine at Penn State College of Medicine in Hershey, Pa., in an email.

"All the research being done on dementia may one day help us to understand it better, but for now, there are basic recommendations to reduce one's risk: do not use tobacco, maintain a strictly normal weight (BMI under 25), exercise regularly, eat a diet high in vegetables and fruits, stay engaged in the community."