This prospective cohort study suggests an association between low physical activity early in childhood and poorer working memory.
Source: López-Vicente M, Garcia-Aymerich J, Torrent-Pallicer J, et al. Are early physical activity and sedentary behaviors related to working memory at 7 and 14 years of age? J Pediatr.2017;188:35–41.e1. doi: 10.1016/j.jpeds.2017.05.079. See AAP Grand Rounds commentary by Dr. Benjamin Doolittle (subscription required).
These prospective cohort studies, especially extending over a few years, are tough to evaluate. They always have problems with follow-up and with confounding unmeasured variables, and this study is no exception. Still, it's a subject worthy of better understanding.
A group of Spanish investigators utilized a population-based birth cohort called INMA (Infancia y Medio Ambiente, also known as Environment and Childhood). They looked at a little more than 1000 children's lifestyle habits, reported by their parents when they were 4 or 6 years of age, and then measured working memory performance at 7 years of age. They found a small decrement in memory scores in children with lower extracurricular physical activity, perhaps not enough to be clinically significant. The study had a few problems that the authors discussed very well. For example, the study questionnaires differed slightly among the 4 different regions of Spain being sampled. (Why couldn't they make them all the same?) I was most concerned, however, by the fact that half of the study population was lost to follow up. That's a big chunk, enough to alter conclusions. Of course, these prospective cohort studies can only demonstrate associations, and cannot determine cause and effect.
I don't know that I came away with any new pearls of wisdom from the study, but I do hope these investigators will continue to look at this cohort as they grow older.
