Last week was the 19th annual installment of the Northwestern Alzheimer Day conference, which is an opportunity for researchers to showcase their work on Alzheimer’s Disease and other dementias for the community at large. I checked out the poster session while I was there, and though I found some of the posters to be pretty interesting (check out Dr. Emily Rogalski’s work on the “Super Agers,” older adults whose brains and performance on tasks of cognitive abilities look more like those of much younger people), the vast majority of the posters covered very technical details about the properties of brain cells - definitely not fodder for this blog.
Instead, I found a new paper looking at the relationship between fluctuations in body weight and risk for dementia. Researchers looked at longitudinal data collected from Israeli civil servants in the 1960’s. What’s longitudinal data, you ask? Terrific question! If you want to know how people’s performances on tasks or answers to questions change over time, then you can ask a group of people to all do the same task or answer the same question at several points in time (like once a week, or once a month, or once a year, etc.), and examine differences in performance at each testing point for each person. This is called a longitudinal study design. For example, if a scientist wanted to know how kids’ appetites change as they get older, she might ask a group of 5th graders how much they eat on a given day, then ask those same kids the same questions again in 7th grade, and again in 9th grade.
In the case of this paper, over 10,000 male Israeli civil servants between the ages of 40 and 70 were asked several questions about their diets and exercise habits in 1963, and again in 1965 and 1968. Then in the year 2000, all of the surviving participants in the survey (2,036 to be precise) were tested for dementia; about 300 received a diagnosis. From there, the research team looked at whether any of the longitudinal survey data from the 1960’s could shed any light on who would later receive a dementia diagnosis. After controlling for known dementia risk factors like income and general health, the researchers found that unstable bodyweight - that is, weight fluctuations between the different time points - was associated with an increased risk of dementia. It didn’t matter whether the participants gained or lost weight: participants whose weights changed the most from point to point had the greatest risk of dementia diagnosis in 2000.
Before you rush off to buy a new bathroom scale, take a deep breath! There’s no evidence here to suggest that unstable weight can cause dementia. Researchers would need to know a lot more about the survey participants and the general incidence of dementia in people living during the 1960’s before any claims about causality can be made. That said, it is still interesting to see how seemingly unrelated aspects of health might be tied together in some way. At the very least, this study opens the door for future work looking at the relationship between dementia and body weight. We know a lot more today about dementia, and a lot more about how to design a good survey, so the next iteration of this line of work could be very informative. Perhaps we will read about it at a Northwestern Alzheimer Day in the future!