Attention-Deficit/Hyperactivity Disorder (ADHD) is a mental disorder that is prevalent among children and adolescents, but it is also common in adults. It is estimated that over 8 million adults in the United States (up to 5% of the population) are affected by adult ADHD.
However, the majority of adults with ADHD are not even aware that they have it. According to several studies, less than 20% of adults with ADHD are aware of their condition, and only a quarter of those who know they have it receive treatment.
A recent study conducted in a California hospital system found a 43% rise in the rate of adult ADHD cases over a period of almost 10 years.
So what is driving these startling statistics?
Experts suggest that there are two potential explanations for the increase in adult ADHD cases. Either it is due to the under-diagnosis of children with ADHD three decades ago, or it is related to unhealthy diet and other lifestyle behaviors.
Impulsivity is a complex and multi-dimensional trait that makes people more likely to react quickly and without thinking to both outside and inside stimuli.
Impulsive individuals may show less concern for the adverse outcomes, not only for themselves but also for others. Impulsivity is a prominent symptom of Attention Deficit/Hyperactivity Disorder (ADHD).
People exhibiting maladaptive or excessive impulsivity may be at risk of developing aggressive behavior and psychiatric illnesses, such as bipolar disorder and substance use disorders.
A study published in the Nutrients Journal investigated the impact of unhealthy dietary habits and lifestyle factors, such as smoking, sleep, alcohol consumption, and physical activity, on the genetic predisposition to impulsivity.
The current observational and cross-sectional study examined the association between impulsivity and dietary habits, lifestyle, and genetic factors. The study involved 33,047 participants (with a mean age of 42 years, of which 60% were female) who participated in the Dutch Lifelines study. Linear regression models with covariate adjustment were employed to assess the impact of diet quality and lifestyle factors on the relationship between attention-deficit/hyperactivity disorder polygenic risk scores (PRS) and the level of impulsivity.
The PRS scores were subjected to Principal Component Analysis (PCA), and the first principal component (PC) was selected as the final PRS score for Attention-Deficit/Hyperactivity Disorder.
Covariates such as gender, age, body mass index (BMI), socioeconomic status, income, occupational status, and education level were taken into account. The PRS scores were computed by multiplying the risk allele doses for each Single Nucleotide Polymorphism (SNP) by its corresponding weight, and then summing up all SNPs.
At the beginning of the study, participants completed a questionnaire consisting of 32 items selected from the NEO Personality Index, which included impulsivity facet components of the neuroticism scale, the excitement-seeking facet of the extraversion scale, and the self-discipline and deliberateness facets of the conscientiousness scale. The participants’ deoxyribonucleic acid (DNA) samples were genotyped, and Sanger sequencing was conducted.
The researchers collected information on the participants’ food consumption in the preceding month using 110-item semi-quantitative food frequency questionnaires (FFQ), which were analyzed to determine the total daily caloric intake in kcal/day using the 2011 Dutch food composition database. The team evaluated reliability by comparing the total daily caloric intake, basal metabolic rate (BMR), and diet quality using inverted Lifelines Diet Score (LLDS-I).
To evaluate physical activity, the Short Questionnaire to Assess Health-Enhancing Physical Activity (SQUASH) questionnaire was used, and the number of weekly minutes spent in moderate to vigorous intensity physical activity (MVPA) was determined. A sensitivity analysis was conducted to assess the impact of interactions between diet, lifestyle, and socioeconomic status on the inflation in the effect size of Attention-Deficit/Hyperactivity Disorder (ADHD) polygenic risk scores.
The study found a significant correlation between Attention-Deficit/Hyperactivity Disorder (ADHD) polygenic risk scores and impulsivity. Greater impulsivity was associated with poorer diets, higher energy and fat intake, and an interaction effect between greater energy intake and the effect of PRS on impulsivity.
The study also revealed that certain lifestyle factors, including sleep duration, smoking habits, alcohol consumption, and MVPA scores, were linked to greater impulsivity. However, no interaction effects were observed between these lifestyle factors and impulsivity.
Moreover, the study revealed that younger age, female gender, higher body mass index, lower educational and occupational status, experiencing stressful events in the previous year, lifetime difficulties, and a history of anxiety and depression were linked to higher impulsivity. However, there was no significant association between sugar intake and impulsivity.
The sensitivity analysis showed small yet statistically significant correlations between ADHD polygenic risk scores and diet indicators, smoking, and sleep duration, confirming the main study’s findings’ robustness.
After adjusting for diets, lifestyle, and socioeconomic status, the effect size of ADHD polygenic risk scores and caloric intake was slightly reduced.
In conclusion, the study demonstrated that a higher energy intake can magnify the link between the polygenic load of ADHD and impulsivity.
The study results emphasized the usefulness of ADHD polygenic risk scores in elucidating impulsivity traits in the general population and supported the genomic correlations between ADHD and impulsivity measures. Nevertheless, it is important to note that ADHD polygenic risk scores could account for only a small portion of the variability in trait impulsivity.
People with a genetic predisposition to ADHD may benefit from reducing their caloric intake in their everyday diet. The findings of the study support the diathesis-stress model of genetic-environmental interactions, wherein genes and stressful environments work together to increase risks (with the stressor being higher energy intake).
In conclusion, the study outcomes offer crucial information about genetic factors and the role of diet in impulsivity. Additional research is necessary to clarify the molecular mechanisms that underlie the interactions between diet and genes.
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