A recent study* published in the ‘Journal of Alzheimer’s Disease’ found that a simple observer rating of ‘How much difficulty did the respondent have remembering things that you asked him/her about?’ was a strong predictor of dementia over a 15 year follow-up period. This study questioned 12,749 people (!) over age 50 and 944 of these developed dementia while being followed up. The observers made the rating after spending 1 to 3 hours interviewing the person face-to-face or by phone, as part of the ‘University of Michigan Health and Retirement Study’. So, the interview itself was effectively a stress test of cognitive function although that was not its purpose. The predictive value of the observer rating scale applied even when participants had strong performances on an objective memory test (remembering words from a long list) and a subjective memory test (they were asked how well they perceived their memory to be).
The observers also rated:
• ‘inattentiveness’, which was found to have better long-term than short-term predictive value,
• ‘worse vocabulary’ (?word-finding difficulty) and ‘often asking to repeat questions’, both of which better predicted dementia short-term than long-term.
The observers, the raters in this study, were ‘trained research assistants’ that is, not experienced clinicians or qualified professionals.
As always, one should not read too much into this observation, or jump too much to conclusions. Certainly, this doesn’t mean that one question could and should in all situations replace a full clinical assessment by a skilled professional. But there may be some things we can learn from this. Here are a couple of thoughts that occurred to me when I read the study.
• Drugs are now available which reduce amyloid load in the brain if used early in the process. Many issues remain about these drugs and their use which I won’t discuss here but they provide an argument for early detection of Alzheimer’s disease, and this study points the way to one method of achieving this. Note that not all dementia is due to Alzheimer’s disease.
• This study reminds us that human beings (the observers in this study) can be very skilled in making observations and judgments. The race to use ‘objective’ questionnaires and tick-the-box tests can undervalue these innate skills. On the other hand, there can be many pitfalls in making such judgments in individual persons and situations. We need to strive to “be objective about being subjective”, as Prof David Maddison once said.
• The observation in this study underlines how important it is for a clinician to listen to family and friends of a person suspected of experiencing cognitive impairment. These family and friends, like the observers in this study, have seen the person functioning well or not-so-well in real world situations, where their cognition is being tested, not by rating scales but by real-world stresses. The clinician then has to look at these family and friend’s observations and make a judgment call about how reliable they appear to be. That requires another human skill for which there are no rating scales.
*Sutin AR and others. ‘A Simple Single Item Rated by an Interviewer Predicts Incident Dementia Over 15 Years’