Insomnia, Alcohol Consumption and ADHD Symptoms in Adults

Patterns of ethanol intake in male rats with partial dopamine transporter deficiency

Mesolimbic dopamine signaling plays a major role in alcohol and substance use disorders as well as comorbidities such as anxiety and depression. Growing evidence suggests that alcohol drinking is modulated by the function of the dopamine transporter (DAT), which tightly regulates extracellular dopamine concentrations. Adult male rats on a Wistar Han background (DAT+/+) and rats with a partial DAT deletion (DAT+/-) were used in this study. First, using fast-scan cyclic voltammetry in brain slices containing the nucleus accumbens core from ethanol-naïve subjects, we measured greater evoked dopamine concentrations and slower dopamine reuptake in DAT+/- rats, consistent with increased dopamine signaling. Next, we measured ethanol drinking using the intermittent access two-bottle choice paradigm (20% v/v ethanol vs. water) across 5 weeks. DAT+/- rats voluntarily consumed less ethanol during its initial availability (the first 30 min), especially after longer periods of deprivation. In addition, DAT+/- males consumed less ethanol that was adulterated with the bitter tastant quinine. These findings suggest that partial DAT blockade and concomitant increase in brain dopamine levels has potential to reduce drinking and ameliorate alcohol use disorder (AUD).

Investigating causal relationships between genetically determined increased risk of attention-deficit/hyperactivity disorder (ADHD) and atopic dermatitis (AD): A Mendelian randomization analysis

Atopic dermatitis (AD) is a chronic, inflammatory skin condition with a huge disease burden. Attention-deficit/hyperactivity disorder (ADHD) is often diagnosed in children, and is associated with symptoms of inattention, hyperactivity and impulsive behaviour. Observational studies have demonstrated associations between AD and ADHD. However, to date, there has been no formal assessment of causal relationship between the two. We aim to evaluate causal relationships between genetically increased risk of AD and ADHD using Mendelian randomization (MR) approach. Two-sample bi-directional MR was conducted to elucidate potential causal relationships between genetically increased risk of AD and ADHD, using the largest and most recent genome-wide association study datasets for AD and ADHD-EArly Genetics & Lifecourse Epidemiology AD consortium (21 399 cases and 95 464 controls) and Psychiatric Genomics Consortium (20 183 cases and 35 191 controls). Genetically determined increased risk of AD is not associated with ADHD based on genetic information: odds ratio (OR) of 1.02 (95% CI -0.93 to 1.11; p = 0.705). Similarly, genetic determined increased risk of ADHD is not associated with an increased risk of AD: OR of 0.90 (95% CI -0.76 to 1.07; p = 0.236). Horizontal pleiotropy was not observed from the MR-Egger intercept test (p = 0.328) Current MR analysis showed no causal relationship between genetically increased risk of AD and ADHD in either direction in individuals of European descent. Any observed associations between AD and ADHD in previous population studies could possibly be due to confounding lifestyle factors such as psychosocial stress and sleeping habits.

Sleep disturbance and psychiatric disorders: a bidirectional Mendelian randomisation study

AIMS

Sleep disturbance is an important factor in the pathophysiology and progression of psychiatric disorders, but whether it is a cause, or a downstream effect is still not clear.

METHODS

To investigate causal relationships between three sleep-associated traits and seven psychiatric diseases, we used genetic variants related to insomnia, chronotype and sleep duration to perform a two-sample bidirectional Mendelian randomisation analysis. Summary-level data on psychiatric disorders were extracted from the Psychiatric Genomics Consortium. Effect estimates were obtained by using the inverse-variance-weighted (IVW), weights modified IVW, weighted-median methods, MR-Egger regression, MR pleiotropy residual sum and outlier (MR-PRESSO) test and Robust Adjusted Profile Score (RAPS).

RESULTS

The causal odds ratio (OR) estimate of genetically determined insomnia was 1.33 (95% confidence interval (CI) 1.22-1.45; p = 5.03 × 10-11) for attention-deficit/hyperactivity disorder (ADHD), 1.31 (95% CI 1.25-1.37; p = 6.88 × 10-31) for major depressive disorder (MDD) and 1.32 (95% CI 1.23-1.40; p = 1.42 × 10-16) for post-traumatic stress disorder (PTSD). There were suggestive inverse associations of morningness chronotype with risk of MDD and schizophrenia (SCZ). Genetically predicted sleep duration was also nominally associated with the risk of bipolar disorder (BD). Conversely, PTSD and MDD were associated with an increased risk of insomnia (OR = 1.06, 95% CI 1.03-1.10, p = 7.85 × 10-4 for PTSD; OR = 1.37, 95% CI 1.14-1.64; p = 0.001 for MDD). A suggestive inverse association of ADHD and MDD with sleep duration was also observed.

CONCLUSIONS

Our findings provide evidence of potential causal relationships between sleep disturbance and psychiatric disorders. This suggests that abnormal sleep patterns may serve as markers for psychiatric disorders and offer opportunities for prevention and management in psychiatric disorders.