Does IQ Influence Association Between Working Memory and ADHD Symptoms in Young Adults?

RBFOX1 and Working Memory: From Genome to Transcriptome Revealed Posttranscriptional Mechanism Separate From Attention-Deficit/Hyperactivity Disorder

Background

Many psychiatric disorders share a working memory (WM) impairment phenotype, yet the genetic causes remain unclear. Here, we generated genetic profiles of WM deficits using attention-deficit/hyperactivity disorder samples and validated the results in zebrafish models.

Methods

We used 2 relatively large attention-deficit/hyperactivity disorder cohorts, 799 and 776 cases, respectively. WM impairment was assessed using the Rey Complex Figure Test. First, association analyses were conducted at single-variant, gene-based, and gene-set levels. Deeper insights into the biological mechanism were gained from further functional exploration by bioinformatic analyses and zebrafish models.

Results

Genomic analyses identified and replicated a locus with rs75885813 as the index single nucleotide polymorphism showing significant association with WM defects but not with attention-deficit/hyperactivity disorder. Functional feature exploration found that these single nucleotide polymorphisms may regulate the expression level of RBFOX1 through chromatin interaction. Further pathway enrichment analysis of potential associated single nucleotide polymorphisms revealed the involvement of posttranscription regulation that affects messenger RNA stability and/or alternative splicing. Zebrafish with functionally knocked down or genome-edited rbfox1 exhibited WM impairment but no hyperactivity. Transcriptome profiling of rbfox1-defective zebrafish indicated that alternative exon usages of snap25a might partially lead to reduced WM learning of larval zebrafish.

Conclusions

The locus with rs75885813 in RBFOX1 was identified as associated with WM. Rbfox1 regulates synaptic and long-term potentiation-related gene snap25a to adjust WM at the posttranscriptional level.

Effect of Adolescent Body Mass Index Trajectories on Working Memory: A Prospective Birth Cohort in Brazil

Most research on the association between high body mass index (BMI) and working memory (WM) has been cross-sectional in design, limiting conclusions about long-term effects of overweight and obesity on WM. The aim of this study was to examine the association of BMI trajectory from 11 to 22 years with WM at 22 years of age. Data from the 1993 Pelotas (Brazil) Birth Cohort Study were analyzed (N = 3,010). Information on BMI was collected at ages 11, 15, 18, and 22 years. Group-based trajectory modeling was used separately for each sex to identify BMI trajectories. Working Memory performance (Digit Span backward score) was examined at age 22. Multiple linear regression was used to assess the association between BMI trajectory from 11 to 22 years and WM at age 22. In both sexes, the trajectory groups were: stable normal weight, stable overweight, and stable obesity. In the adjusted analyses, women in the stable-obesity group had lower WM at 22 years (β = -.49; 95% CI: -0.75, -0.23; p < .001) than those in the stable-normal weight group. No associations were found between BMI trajectories and WM in men. This study may contribute to future investigations of possible explanatory avenues for the association between high BMI and WM.