Dementia Risk Persists Into Advanced Age

Many assume that reaching age 90 without dementia means they have escaped it. New research from the University of California, Davis Health, and Kaiser Permanente suggests otherwise. The study, part of the ongoing LifeAfter90 project, tracked over 800 adults aged 90 and older. It found that dementia risk continues into advanced age, varying by sex, race, ethnicity, and genetics.

Study Findings

The research, published in The Lancet Healthy Longevity, is one of the first to analyze dementia risk in a diverse group over 90 without prior dementia signs. Rachel Whitmer, a UC Davis Health professor, highlighted known differences in dementia rates among those 65 and older, noting women tend to have higher risks. The question was whether these trends persisted beyond 90.

Kaiser Permanente members participating in the study underwent assessments every six months. Many had long health records dating back to the 1960s, allowing comprehensive analysis. Findings revealed:

• Women over 90 remained more vulnerable to dementia than men.
• Black participants faced a 75% greater dementia risk than Asian participants. Black and Hispanic participants had significantly higher incidence rates than White and Asian participants.

Hilary Colbeth, a UC Davis postdoctoral scholar, noted the persistence of racial and ethnic disparities into the 10th decade of life.

APOE Gene and Dementia

Researchers examined the APOE gene, linked to Alzheimer’s disease risk. The APOE2 variant offers protection, while APOE4 increases risk. The study found APOE2 reduced dementia risk by about 60% even after age 90. APOE4, while not raising risk significantly across all participants, nearly doubled the risk among Black participants and had differing impacts based on sex.

Interestingly, some participants remained cognitively healthy despite having APOE4 or other risk factors, prompting further investigation into protective factors.

Broad Implications

Lisa George, founder of Talk Tribeca Psychiatry, explains these findings challenge the misconception that surviving to 90 without dementia means safety. Age remains the main risk factor, and dementia complexity increases in the ‘oldest old’ as multiple processes can affect the brain.

George urges caution, advising that not every memory issue in very old adults signals dementia. Conditions like depression, anxiety, poor sleep, and medication side effects can mimic dementia symptoms.

The study’s authors emphasize the importance of recognizing elevated risk groups even at very old age. Whitmer stressed, “Doctors should note certain groups’ risks and discuss risk reduction for all.”

Future Research Directions

The findings underscore that dementia risk does not plateau after 90, raising questions on how aging, genetics, and health disparities influence cognition in the ‘oldest old.’ The need for research on this rapidly growing age group is clear. Alzheimer’s research is focusing on early detection and prevention, with new biomarker tests showing promise for identifying risk before symptoms appear.

Insights from the LifeAfter90 study could guide future screening, treatment, and prevention strategies for an aging population.