A certain gene, called ApoE, is considered by many to be the primary genetic risk factor in late-onset Alzheimer’s disease.
However, not everyone with one or even two copies of this gene will go on to develop the condition.
In fact, less than half of those with this genetic predisposition are actually diagnosed with Alzheimer’s disease.
So, why do the remaining 53 percent stay healthy? Scientists — led by Becca Levy, from the Yale School of Public Health in New Haven, CT — set out to answer this question in their new study, which was published in the journal PLOS One.
The new research investigates for the first time whether environmental — and therefore modifiable — factors such as beliefs around aging can influence the risk of developing dementia.
Levy and team examined 4,765 people who did not have dementia at the beginning of their study: 91 percent of the participants were white, and as many as 26 percent of them had an E4 variant of the ApoE gene — the variant most associated with Alzheimer’s.
The participants were at least 60 years old and were all recruited from the Health and Retirement Study. Their attitudes toward age were assessed using a subscale of the Philadelphia Geriatric Center Morale Scale.
The questionnaire included items such as, “The older I get, the more useless I feel.” These were statements that the participants had to express their agreement or disagreement with.
They were followed for a period of 4 years, and every 2 years they were given questionnaires that assessed their cognitive skills. Levy and colleagues carried out a prospective logistic regression analysis over those 4 years.
Among those that had the ApoE E4 genetic variant, people with positive beliefs about age were “49.8 percent less likely to develop dementia than those with negative age belief.”
The authors speculate on the mechanism that might explain these results, suggesting that negative age beliefs can exaggerate stress, whereas positive ones can attenuate its negative effects.
They also reference studies that have shown how stress can bring about the development of dementia and conclude, “The results of this study suggest that positive age beliefs, which are modifiable and have been found to reduce stress, can act as a protective factor, even for older individuals at high risk of dementia.”
In fact, there is a wide range of literature available attesting to the common negative stereotypes of the elderly, as the media often portrays them as “sad, depressed, senile, wrinkled, unattractive, and dependent.”
Such biased portrayals in the media, together with discrimination practices in the workplace, tend to encourage negative attitudes toward the elderly.
But, as the study authors write, “The reduction of stress by positive age beliefs could potentially contribute to a lower incidence of dementia among older individuals in general and specifically among those with ApoE E4.”
The study may be particularly relevant given that the senior population in the United States is expected to double by the year 2030.