Summary: A new longitudinal study examines how adolescent BMI relates to cognitive performance in midlife and how socioeconomic position shapes that relationship.
Source: Hebrew University of Jerusalem.
Study of Israeli adolescents demonstrates the influence of socioeconomic position on later cognitive function
Rates of overweight and obesity among adolescents have risen sharply over recent decades, affecting a large share of youth in many developed countries. While a higher body mass index (BMI) in adulthood has been linked to poorer cognitive outcomes later in life, less is known about whether elevated BMI in adolescence predicts cognitive performance in midlife. BMI is calculated as weight in kilograms divided by the square of height in meters.
Researchers at the Hebrew University-Hadassah Braun School of Public Health and Community Medicine investigated the relationship between long-term BMI patterns beginning in adolescence and cognitive function around age 50. The study, led by Prof. Jeremy Kark in collaboration with colleagues in Israel and the United States, appears in the Journal of Alzheimer’s Disease.
The research followed 507 participants for more than three decades, starting with measured height and weight at age 17. At ages 48–52 the participants completed a computerized cognitive assessment covering global cognition and specific cognitive domains. The study also collected comprehensive indicators of socioeconomic position (SEP) from childhood and adulthood. Using mixed models, the investigators estimated each participant’s life-course BMI burden and BMI trajectory from age 17 to midlife, then used multiple regression to evaluate associations of adolescent and cumulative BMI, as well as stature and growth patterns, with midlife cognition.
Key findings indicate that higher BMI in late adolescence and a greater cumulative BMI burden across the life course were both associated with lower global cognitive performance in midlife. These associations remained after adjusting for demographic factors and for measures of childhood and adult socioeconomic position. Notably, the adverse association between BMI and cognition was concentrated among individuals from lower childhood socioeconomic backgrounds: interactions with childhood SEP were statistically significant, indicating the relationship is not uniform across all social groups.
In addition to BMI effects, stature and growth timing were relevant. Shorter height in adolescence was linked to poorer cognitive performance at midlife, while continued growth into late adolescence—reflecting later pubertal or growth timing—was associated with better cognitive outcomes for women. These results suggest that early-life conditions that influence final height and growth timing may also bear on later cognitive health.
Prof. Jeremy Kark, the study’s senior author, emphasized that the findings support the idea that an adverse influence of higher BMI on cognitive function may begin in adolescence and continue through adulthood, independently of adult BMI changes. Lead author Irit Cohen-Manheim noted the importance of stature and late growth: taller stature correlated with better global cognition regardless of socioeconomic position, while late adolescent growth appeared protective for women specifically.
The authors highlight the critical role of socioeconomic position in shaping these associations. Childhood household SEP in particular modified the link between adolescent BMI and midlife cognition: the inverse association—higher adolescent BMI associated with poorer midlife cognition—was essentially restricted to those from lower childhood SEP. This suggests that early-life social and economic conditions can amplify or mitigate the long-term cognitive risks associated with elevated adolescent BMI.
Given evidence that cognitive impairment in midlife elevates the risk of subsequent dementia, these findings have potential clinical and public health relevance. The study underscores the need to address adolescent overweight and obesity—especially among socioeconomically disadvantaged populations—and to consider early-life social conditions when assessing long-term cognitive risk.
The research team includes investigators from the Hebrew University-Hadassah Braun School of Public Health and Community Medicine (Jerusalem, Israel); NeuroTrax Corporation (Modiin, Israel); Centre for Medical Decision Making, Ono Academic College (Kiryat Ono, Israel); Department of Neurology, Albert Einstein College of Medicine (Bronx, NY, USA); and the Biostatistics Unit, Gertner Institute for Epidemiology and Health Policy Research (Tel-Hashomer, Israel).
Funding: Supported by the Chief Scientist of the Israel Ministry of Health, the Israel Science Foundation, and the US–Israel Binational Science Foundation.
Source: Dov Smith — Hebrew University of Jerusalem
Original research: Cohen-Manheim I, Doniger GM, Sinnreich R, Simon ES, Murad H, Pinchas-Mizrachi R, Kark JD. “Body Mass Index, Height and Socioeconomic Position in Adolescence, Their Trajectories into Adulthood, and Cognitive Function in Midlife.” Journal of Alzheimer’s Disease. Published online December 6, 2016. doi:10.3233/JAD-160843
Background: The relation of life-course anthropometric measures to midlife cognitive function has been inadequately explored, and socioeconomic position is seldom fully considered. This study examines whether cumulative high-ranked BMI from adolescence through adulthood, BMI trajectory, and stature are associated with cognitive performance in midlife.
Methods: Height and weight were measured from age 17 over a 33-year follow-up. A total of 507 participants completed a NeuroTrax computerized cognitive assessment at ages 48–52. Life-course socioeconomic position was assessed using multiple measures. Investigators calculated area-under-the-curve (AUC) metrics to represent total life-course BMI burden and BMI trends (incremental AUC) from age 17 to midlife. Multiple regression models tested associations of BMI and height with global cognition and five cognitive domains.
Results: Higher BMI in late adolescence and a greater total life-course BMI burden were associated with poorer global cognition (standardized beta = –0.111, p = 0.005 and beta = –0.105, p = 0.018, respectively) after adjusting for childhood and adult SEP and demographic factors. The associations of higher adolescent and midlife BMI with poorer cognition were restricted to individuals with low childhood SEP (interaction p < 0.05). Shorter adolescent stature correlated with lower cognition (beta = 0.115, p = 0.040), while continued late growth in women related to better cognitive performance (beta = 0.213, p = 0.007).
Conclusion: Elevated BMI linked to poorer cognitive function can be detected beginning in adolescence and appears concentrated among those from lower childhood socioeconomic backgrounds. Taller stature in both sexes and later growth in women were associated with better midlife cognitive outcomes.
Readers are welcome to share this summary of the research while acknowledging the Hebrew University of Jerusalem and the original study authors.