Research at the Florida State University College of Medicine has identified a potential low-cost method for predicting if a person is at risk of developing dementia.

By analyzing data from nearly 13,000 subjects who participated in a long-term aging study, researchers found that an interviewer's rating of a cognitively healthy person's memory successfully predicted the likelihood of developing dementia over a 15-year period. Their findings will be published in the Journal of Alzheimer's Disease.

"Our findings show that interviewers were able to detect deficits in the memory of participants that predicted higher risk of developing dementia over time," said research author Angelina Sutin, professor of Behavioral Sciences and Social Medicine. "The interviewer ratings of memory were particularly important for participants who were among the top performers on objective memory tests."

The results show that ratings of a person's memory performance by an interviewer could be a valuable alternative or addition to other methods of detection, such as self reporting or cognitive testing.

Sutin's team analyzed 15 years of data involving nearly 13,000 people without cognitive impairment at baseline who participated in the University of Michigan Health and Retirement Study, or HRS, and whose memory was rated by their interviewer. The longitudinal study surveys a representative sample of adults aged 50 and older about their health, financial situation and well-being every two years for as long as they choose to remain in the study.

Sutin's sample included participants who were interviewed in 2006 and scored within the normal range of cognitive function during their first interview and had at least one follow-up assessment of cognition between 2008–2020.

Interviewers were trained research assistants working for the HRS who conducted the 2–3 hour interviews and rated the item, "How much difficulty did the respondent have remembering things that you asked (him/her) about?" from 1 (no difficulty) to 5 (could not do at all).

Interviewer-rated memory was entered as a predictor of incident dementia across the 15-year follow-up period. They found that each 1-point increase in poor memory as rated by the interviewer (on the 1–5 scale) was associated with a 40% increase in risk of developing dementia at some point over the follow-up period. This association was apparent even after accounting for potential swaying factors such as depression and poor hearing. Whether the interview was face-to-face or over the phone had no effect on the results.

Notably, the association was even stronger among participants with the best objective memory performance (remembering many words from a long list of words) and subjective memory (how well someone perceives their memory to be). Both objective and subjective memory have been useful in detecting cognitive deficits preceding a diagnosis of dementia.

Of particular interest, Sutin said, is that the results were consistent even among participants who scored in the top quartile of memory function at baseline. Such performance on an objective memory test typically suggests that the individual has good cognitive function and is not at risk of impairment.

"This simple rating by an interviewer is predictive of who develops dementia, particularly when traditional measures of memory function do not necessarily detect memory deficits," Sutin said. "And the association is similar across age, sex, race, ethnicity and education, which suggests it may be broadly predictive across populations. Overall, we believe these findings show that interviewer-rated memory was a good marker of future dementia among the most cognitively healthy."

Sutin said the findings support growing evidence for the importance of subjective ratings of memory and extends the association to observers who are not necessarily well-acquainted with the target. Clinicians generally rely on family members in gathering information on cognitive function. This study indicates that an interview with a stranger can also provide valuable information on prospective cognitive health.

Based on the findings, a simple interviewer rating has the long-term power to predict who may develop dementia and could be useful for clinicians in providing effective treatment.