Study Finds Possible Link Between ADHD Risk, Cholesterol Levels During Pregnancy

Scientists have found a possible link between maternal cholesterol levels and the risk of attention-deficit-hyperactivity disorder (ADHD) in children, with boys being more susceptible to the effect than girls.

This work, finding that suboptimal maternal cholesterol levels—in particular low high-density lipoprotein (HDL)—may increase the risk of ADHD is different because prior studies on cholesterols and brain functions were mostly in adults. Researchers said this study, while needing additional investigation, raises new hypotheses about ADHD gender differences and future targets to prevent the disorder.

Researchers used data from the Boston Birth Cohort, followed from birth up to age 15. The cohort is mostly urban, low income, and minority. The final analyses included 1479 mother-infant pairs: 303 children with ADHD, and 1176 neurotypical children.

Results showed that a low maternal HDL cholesterol level (≤60 mg/dL) was associated with an increased risk of ADHD, compared to a higher maternal HDL cholesterol level, after adjusting for covariables.

A “J” shaped relationship was observed between triglycerides and ADHD risk. The associations with ADHD for maternal HDL cholesterol and triglycerides were more pronounced among boys. The researchers said the study sheds new light on the ADHD sex difference by demonstrating that boys are more vulnerable than girls to suboptimal maternal cholesterol levels.

There was a significant association between maternal cholesterol levels, particularly HDL cholesterol and triglycerides measured 24 to 72 hours after delivery (a proxy of peripartum maternal cholesterol levels). The authors noted that the association is not significant for the risk of other neurodevelopmental disorders.

Researchers wrote that the findings could have several implications. First, they suggested that pregnant women maintain a relatively higher level of HDL cholesterol. The current clinical cut-off point for HDL cholesterol (>50 mg/dL) for nonpregnant women, as recommended by the American Heart Association for reducing the risk of heart disease, may not be adequate for protecting against ADHD in offspring. The study said perhaps a higher cut-off point (>60 mg/dL) is needed for identifying the fetus at risk for future ADHD.

The study had a few limitations. It only included a single measurement of non-fasting maternal cholesterol taken 24 to 72 hours after delivery. Lipid levels collected throughout pregnancy would be more optimal. Also, the change in lipid levels between 24 and 72 hours after delivery might add another potential variable.

The population studied (urban, low-income, mostly minority setting) is at higher risk of exposure to other ADHD risk factors. The analyses adjusted for known risk factors of ADHD, but could not capture all of them.

Reference

Ji Y, Riley AW, 1, Lee L, et al. A prospective birth cohort study on maternal cholesterol levels and offspring attention deficit hyperactivity disorder: new insight on sex differences. Brain Sci. 2018; 8(1):3. doi:10.3390/brainsci8010003. Published December 23, 2017. January 4, 2018.