Association between altered lipid profiles and attention deficit hyperactivity disorder in boys

Genetic Association of Lipids and Lipid-Lowering Drug Target Genes With Attention Deficit Hyperactivity Disorder

BACKGROUND

Lipid metabolism plays an essential role in nervous system development. Cholesterol deficiency leads to a variety of neurodevelopmental disorders, such as autism spectrum disorder and fragile X syndrome. There have been a lot of efforts to search for biological markers associated with and causal to ADHD, among which lipid is one possible etiological factor that is quite widely studied. We aimed to evaluate the causal relationship between lipids traits, lipid-lowering drugs, and attention deficit hyperactivity disorder (ADHD) outcomes using Mendelian randomization (MR) studies.

METHODS

We used summary data from genome-wide association studies to explore the causal relationships between circulating lipid-related traits and ADHD. Then, quantitative trait loci for the expression of lipid-lowering drug target genes and genetic variants associated with lipid traits were extracted. Summary-data-based MR and inverse-variance-weighted MR (IVW-MR) were used to investigate the correlation between the expression of these drug-target genes and ADHD.

RESULTS

After rigorous screening, 939 instrumental variables were finally included for univariable mendelian randomization analysis. However, there is no correlation between lipid profile and ADHD risk. Drug target analysis by IVW-MR method observed that APOB-mediated low-density lipoprotein cholesterol was associated with lower ADHD risk (odds ratio [OR] = 0.90, 95% confidence interval [CI] [0.84, 0.97]; p = .007), whereas LPL-mediated triglycerides levels were associated with a higher risk of ADHD (OR = 1.13, 95% CI [1.06, 1.21]; p < .001).

CONCLUSION

Our results suggest that APOB gene and LPL gene may be candidate drug target genes for the treatment of ADHD.

What Is the Link between Attention-Deficit/Hyperactivity Disorder (ADHD) and Dyslipidemia in Adults? A German Retrospective Cohort Study

Background: Alterations in the serum lipid profile have been suspected in many psychiatric disorders, such as schizophrenia and depression. However, studies on lipid status in attention-deficit/hyperactivity disorder (ADHD) are sparse and inconsistent. Methods: Using the nationwide, population-based IQVIA Disease Analyzer database, this retrospective cohort study included 5367 outpatients from general practices in Germany aged ≥18 years with a documented first diagnosis of ADHD between January 2005 and December 2021 and 26,835 propensity score-matched individuals without ADHD. Study outcomes were the first diagnosis of lipid metabolism disorders as a function of ADHD within up to 10 years of the index date. The cumulative 10-year incidence was analyzed using Kaplan-Meier curves and compared using the log-rank test. In addition, univariate Cox regression analyses were performed. Results: In the regression analysis, there was no significant association between ADHD and subsequent lipid metabolism disorders in the total population (HR: 0.94; 95% CI: 0.83-1.08), among women (HR: 1.04; 95% CI: 0.84-1.28), and among men (HR: 0.89; 95% CI: 0.74-1.06). In addition, no significant association was observed in the disease-stratified analyses. Conclusions: The findings of this study indicate that ADHD does not exert an influence on lipid metabolism. However, further investigation is warranted, particularly with respect to pharmacological interventions.

Childhood internalizing and externalizing problems and cardiovascular and diabetes mellitus risk in adolescence

BACKGROUND

Among adults, common psychopathology is a risk factor for cardiovascular diseases (CVD) and type 2 diabetes mellitus (T2DM). We investigated whether childhood internalizing and externalizing problems are prospectively associated with clinically elevated CVD and T2DM risk factors in adolescence.

METHODS

Data were from the Avon Longitudinal Study of Parents and Children. Childhood internalizing (emotional) and externalizing (hyperactivity and conduct) problems were rated on the Strengths and Difficulties Questionnaire (parent version) (N = 6442). BMI was measured at age 15 and triglycerides, low-density lipoprotein cholesterol and homeostasis model assessment of insulin resistance, IR, were assessed at age 17. We estimated associations using multivariate log-linear regression. Models were adjusted for confounding and participants attrition.

RESULTS

Children with hyperactivity or conduct problems were more likely to become obese and to develop clinically high levels of triglycerides and HOMA-IR in adolescence. In fully adjusted models, IR was associated with hyperactivity (relative risk, RR = 1.35, 95 % confidence interval, CI = 1.00-1.81) and conduct problems (RR = 1.37, CI = 1.06-1.78). High triglycerides were associated with hyperactivity (RR = 2.05, CI = 1.41-2.98) and with conduct problems (RR = 1.85, CI = 1.32-2.59). BMI only minimally explained these associations. Emotional problems were not associated with increased risk.

LIMITATIONS

Residual attrition bias, reliance on parent's reports of children's behaviors, non-diverse sample.

CONCLUSIONS

This research suggests that childhood externalizing problems might be a novel independent risk factor for CVD/T2DM. Future research should corroborate these findings and investigate mechanisms. Pediatricians may need to assess and treat CVD/T2DM risk factors in adolescents with a history of externalizing problems.

The role of Smo-Shh/Gli signaling activation in the prevention of neurological and ageing disorders

Sonic hedgehog (Shh) signaling is an essential central nervous system (CNS) pathway involved during embryonic development and later life stages. Further, it regulates cell division, cellular differentiation, and neuronal integrity. During CNS development, Smo-Shh signaling is significant in the proliferation of neuronal cells such as oligodendrocytes and glial cells. The initiation of the downstream signalling cascade through the 7-transmembrane protein Smoothened (Smo) promotes neuroprotection and restoration during neurological disorders. The dysregulation of Smo-Shh is linked to the proteolytic cleavage of GLI (glioma-associated homolog) into GLI3 (repressor), which suppresses target gene expression, leading to the disruption of cell growth processes. Smo-Shh aberrant signalling is responsible for several neurological complications contributing to physiological alterations like increased oxidative stress, neuronal excitotoxicity, neuroinflammation, and apoptosis. Moreover, activating Shh receptors in the brain promotes axonal elongation and increases neurotransmitters released from presynaptic terminals, thereby exerting neurogenesis, anti-oxidation, anti-inflammatory, and autophagy responses. Smo-Shh activators have been shown in preclinical and clinical studies to help prevent various neurodegenerative and neuropsychiatric disorders. Redox signalling has been found to play a critical role in regulating the activity of the Smo-Shh pathway and influencing downstream signalling events. In the current study ROS, a signalling molecule, was also essential in modulating the SMO-SHH gli signaling pathway in neurodegeneration. As a result of this investigation, dysregulation of the pathway contributes to the pathogenesis of various neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD).Thus, Smo-Shh signalling activators could be a potential therapeutic intervention to treat neurocomplications of brain disorders.

Long-term changes in serum levels of lipoproteins in children and adolescents with attention-deficit/hyperactivity disorder (ADHD)

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder affecting approximately 5% of children worldwide. The causal mechanisms of ADHD remain unclear as the aetiology of this disorder seems to be multifactorial. One research field addresses the impact on lipid metabolism and particularly serum lipid fractions on the development of ADHD symptoms. This post hoc analysis aimed to investigate long-term changes in serum levels of lipoproteins in children and adolescents with ADHD and controls. Data of German children and adolescents from the nationwide and representative "Kinder- und Jugendgesundheitssurvey (KiGGS)" study were analysed at baseline and at a ten-year follow-up. At the two time points, participants in the control group were compared with those in the ADHD group, both before and after propensity score matching. Differences in total cholesterol, low-density lipoproteins (LDL), high-density lipoproteins (HDL) and triglycerides were assessed between matched children with and without ADHD. In addition, subgroups with versus without methylphenidate use were compared at both time points. At baseline before matching, there were no significant differences for lipid parameters between participants in the ADHD group (n = 1,219) and the control group (n = 9,741): total cholesterol (Exp(ß) = 0.999, 95%-CI 0.911-1.094, p = .979), LDL (Exp(ß) = 0.967, 95%-CI 0.872-1.071, p = .525), HDL (Exp(ß) = 1.095, 95%-CI 0.899-1.331, p = .366) and triglycerides (Exp(ß) = 1.038, 95%-CI 0.948-1.133, p = .412). Propensity score matching confirmed the non-significant differences between the ADHD and non-ADHD group at baseline. At the 10-year follow-up, n = 571 participants fulfilled complete inclusion criteria, among them 268 subjects were classified as ADHD. The two groups did not significantly differ in lipid fractions, neither cross-sectionally nor with regard to long-term changes. There was also no significant difference between methylphenidate subgroups. In this sample of children and adolescents we could not reveal any significant associations between serum lipid fractions and the diagnosis of ADHD, neither cross-sectionally nor longitudinally; even when methylphenidate use was considered. Thus, further studies using larger sample sizes are required to investigate putative long-term changes in serum lipid fractions related to ADHD.

The Relationship Between Blood Lipid and Attention-Deficit/Hyperactivity Disorder (ADHD) in an Obese Population of Chinese Children: An Obesity-Stratified Cross-Sectional Study

BACKGROUND

Although obesity has been related to attention-deficit/hyperactivity disorder (ADHD), few studies have examined the relationship between blood lipid levels and ADHD in children. We aimed to evaluate whether increased blood lipid levels are associated with the prevalence of ADHD in children.

METHODS

A total of 1179 children were studied in the cross-sectional analysis. Multivariate logistic regression and linear regression analyses were performed to evaluate the association of blood lipid levels with the prevalence of ADHD in children.

RESULTS

In 1179 children, the average age was 10.4 years, and the percentage of boys was 50.3%. 97 (8.2%) of the children were diagnosed with ADHD. The logistic regression analysis demonstrated that elevated levels of total cholesterol (OR=2.001, 95% CI 1.247-3.541, P-trend=0.024), triglycerides (OR=1.776, 95% CI 1.448-2.187, P-trend=0.003) and LDL (low density lipoprotein; OR=2.016, 95% CI 1.335-3.966, P-trend<0.001) and reduced levels of HDL (high density lipoprotein; OR=0.577, 95% CI 0.298-0.948, P-trend=0.023) were associated with the prevalence of ADHD after adjustments were made for age, sex, body mass index (BMI), residence type, maternal smoking during pregnancy, breastfeeding and breastfeeding length, maternal and paternal educational levels, and marital status of parents in Model 3. The stratified analysis using "obese" as a covariate showed that elevated levels of total cholesterol, triglycerides and LDL and reduced levels of HDL were independently associated with an increased risk of ADHD in obese children.

CONCLUSION

Increased blood lipid levels were associated with ADHD in obese children.

Genome-Wide DNA Methylation Patterns in Persistent Attention-Deficit/Hyperactivity Disorder and in Association With Impulsive and Callous Traits

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder that often persists into adulthood. ADHD and related personality traits, such as impulsivity and callousness, are caused by genetic and environmental factors and their interplay. Epigenetic modifications of DNA, including methylation, are thought to mediate between such factors and behavior and may behave as biomarkers for disorders. Here, we set out to study DNA methylation in persistent ADHD and related traits. We performed epigenome-wide association studies (EWASs) on peripheral whole blood from participants in the NeuroIMAGE study (age range 12-23 years). We compared participants with persistent ADHD (n = 35) with healthy controls (n = 19) and with participants with remittent ADHD (n = 19). Additionally, we performed EWASs of impulsive and callous traits derived from the Conners Parent Rating Scale and the Callous-Unemotional Inventory, respectively, across all participants. For every EWAS, the linear regression model analyzed included covariates for age, sex, smoking scores, and surrogate variables reflecting blood cell type composition and genetic background. We observed no epigenome-wide significant differences in single CpG site methylation between participants with persistent ADHD and healthy controls or participants with remittent ADHD. However, epigenome-wide analysis of differentially methylated regions provided significant findings showing that hypermethylated regions in the APOB and LPAR5 genes were associated with ADHD persistence compared to ADHD remittance (p = 1.68 * 10-24 and p = 9.06 * 10-7, respectively); both genes are involved in cholesterol signaling. Both findings appeared to be linked to genetic variation in cis. We found neither significant epigenome-wide single CpG sites nor regions associated with impulsive and callous traits; the top-hits from these analyses were annotated to genes involved in neurotransmitter release and the regulation of the biological clock. No link to genetic variation was observed for these findings, which thus might reflect environmental influences. In conclusion, in this pilot study with a small sample size, we observed several DNA-methylation-disorder/trait associations of potential significance for ADHD and the related behavioral traits. Although we do not wish to draw conclusions before replication in larger, independent samples, cholesterol signaling and metabolism may be of relevance for the onset and/or persistence of ADHD.

Metabolomics study of the prefrontal cortex in a rat model of attention deficit hyperactivity disorder reveals the association between cholesterol metabolism disorder and hyperactive behavior

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disease for which specific biomarkers and pathological mechanisms have yet to be identified. Methylphenidate (MPH) is commonly used to treat ADHD, but its therapeutic mechanisms and its impact on brain metabolites remain unclear. Metabolomics can help to discover biomarkers and identify pathophysiological mechanisms. We adopted an untargeted metabolomics approach based on gas chromatography-mass spectrometry to investigate the potential biomarkers and pathogenesis of ADHD. Ten Wistar-Kyoto (WKY) rats were chosen as healthy controls (vehicle, i.g.). Twenty young spontaneously hypertensive rats (SHR) were randomly allocated to the SHR group (vehicle, i.g.) and MPH group (2 mg/kg/day, i.g.). We identified 103 metabolites from the prefrontal cortex (PFC). Orthogonal partial least square-discriminate analysis showed the differential expression of these metabolites between the groups. Multivariate and univariate statistical analyses isolated 12 metabolites that differed significantly between the WKY and SHR groups: 3-hydroxymethylglutaric acid, 3-phosphoglyceric acid, adenosine monophosphate, cholesterol, lanosterol, and o-phosphoethanolamine; 3-hydroxymethylglutaric acid and cholesterol were reversed with MPH treatment. Pathway and enrichment analyses revealed that the altered metabolites belonged to the cholesterol metabolism pathways. ELISA and western blotting showed that the activity of 3-hydroxy-3-methyl-glutaryl-CoA reductase and the expression of sterol regulatory element-binding protein-2 and ATP-binding cassette transporter A1 were reduced in the PFC of the SHR; the latter two proteins were upregulated by MPH. In conclusion, metabolomics analysis identified potential biomarkers that influence cholesterol metabolism and may be implicated in the development of ADHD-like behavior. MPH can regulate cholesterol metabolism in the PFC of ADHD models. This study uncovered potential biomarkers and pathways involved in ADHD, providing new insight into its pathogenesis.

Attention Deficit/Hyperactivity, the Metabolic Syndrome, and Type 2 Diabetes

PURPOSE OF REVIEW

To present current data on the coexistence of attention deficit hyperactivity disorder (ADHD) and the metabolic syndrome and type 2 diabetes mellitus in adults and children and to discuss possible mechanisms.

RECENT FINDINGS

Emerging data suggest that risk factors for obesity and insulin resistance such as diabetes during pregnancy and intrauterine growth failure may also have a role in the development of ADHD. Furthermore, ADHD and obesity share lifestyle factors, such as abnormal eating patterns, binge eating, and a sedentary lifestyle. ADHD is a risk factor for components of the metabolic syndrome, particularly obesity and type 2 diabetes mellitus, and also hypertension, both in adults and youth. Associations of ADHD with obesity, diabetes, and hypertension have been ascertained, and various mechanisms have been proposed. Research is needed to decipher the shared genetic, pharmacological, and lifestyle risk factors. Individuals with ADHD should be treated as a high-risk group for cardiometabolic complications.