Tokyo psychiatrist, Dr. Douglas Berger, comments on the “The Influence of Diet on ADHD” by Kathleen F. Holton, PhD, MPH, Jeanette M. Johnstone, PhD, Diane D. Stadler, PhD, RD, and Joel T. Nigg, PhD, September 30, 2016 issue of the Psychiatric Times.
The authors of this PT article reference a case-controlled study in China that looked at the risk of ADHD and diet. They state that a diet high in minerals and protein suggested a 47% reduced risk of ADHD.
The study: Dietary, Nutrient Patterns and Blood Essential Elements in Chinese Children with ADHD
found 113 ADHD vs 85 non-ADHD subjects in the low mineral/protein diet (i.e., 57% of the total of low mineral/protein dieters had ADHD) compared with 76 ADHD vs 121 non-ADHD subjects in the total high mineral/protein diet (i.e., 39% of the high mineral/protein dieters had ADHD). See Table 5 in the paper.
One could say that 39% is still .68 of the 57% so that 68% of the children on the high mineral/protein diet still had ADHD as a % of those that had ADHD on the low diet. This seems less “impressive” than the 47% “lower risk” interpretation. Note that the paper’s wording is only that a “mineral-protein nutrient pattern rich in zinc, protein, phosphorus, selenium, calcium and riboflavin was INVERSELY ASSOCIATED with ADHD”.
This is different than a clear lowering of risk by a certain %. The paper is giving percentages in a population sample with different attributes, not a decrease in % of a treated population. Wording can be deceptive.
- ADHD in the families with ADHD children may not prepare as healthy a diet for these children so that ADHD may be the cause of poor diet and not the reverse. Per the paper, “Compared with the controls, the subjects with ADHD were more likely to suffer from emotional abuse, have low maternal education and maternal abortion history along with a higher likelihood of a family history of ADHD”.
- This was an epidemiologic study with a factor analysis, it is not a prospective clinical trial searching for superiority of one intervention given double-blindly vs another. This means that a specific dietary type or factor is not tested for efficacy in ADHD, it is only an association analysis.
- The diagnosis was made by clinical interview, not a definitive biological test. Reliability would be increased if the study only included subjects with severe ADHD and did separate studies on purely inattentive and purely hyperactive +/- inattentive subjects.
A lot more rigor is required before we can say that 47% of the risk for ADHD is reduced by a special diet, and invoking dietary factors at this stage may cause many ADHD families to avoid other treatments for their children.
It is premature to imagine that the incidence of ADHD in the U.S. will all of a sudden go from the current 11% to 6% by dietary changes.
Doug Berger, M.D., Ph.D.
US Board Certified Psychiatrist
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