Generalized anxiety and major depression have become increasingly common in the United States, affecting 18.6 percent of the adult population. Mood disorders can be debilitating, and are often correlated with poor general health, life dissatisfaction, and the need for disability benefits due to inability to work. Recent evidence suggests that some mood disorders have a circadian component, and disruptions in circadian rhythms may even trigger the development of these disorders. However, the molecular mechanisms of this interaction are not well understood. Polymorphisms in a circadian clock-related gene, PER3, are associated with behavioral phenotypes (extreme diurnal preference in arousal and activity) and sleep/mood disorders, including seasonal affective disorder (SAD). Here we show that two PER3 mutations, a variable number tandem repeat (VNTR) allele and a single-nucleotide polymorphism (SNP), are associated with diurnal preference and higher Trait-Anxiety scores, supporting a role for PER3 in mood modulation. In addition, we explore a potential mechanism for how PER3 influences mood by utilizing a comprehensive circadian clock model that accurately predicts the changes in circadian period evident in knock-out phenotypes and individuals with PER3-related clock disorders.

Anxiety and other mood disorders, such as major depressive disorder (MDD) and seasonal affective disorder (SAD), affect nearly one-fifth of the global population and disproportionately affect young adults. Individuals affected by mood disorders are frequently plagued by sleep and circadian problems, and recent genetic studies provide ample support for the association of circadian and sleep syndromes with depression and anxiety. Mathematical modeling has been crucial in understanding some of the essential features of the mammalian circadian clock and is now a vital tool for dissecting how circadian genes regulate the molecular mechanisms that influence mood. Here, we model the effect of five clock gene polymorphisms, previously linked to mood disorders, on circadian gene expression and, ultimately, on the period length and amplitude of the clock, two parameters that dictate the phase, or alignment, of the clock relative to the environment. We then test whether these gene variants are associated with circadian phenotypes (Horne-Ostberg Morningness-Eveningness scores) and well-established measures of depression (Beck Depression Inventory) and anxiety (State-Trait Anxiety Inventory) in a population of undergraduates ( n = 546). In this population, we find significant allelic and/or genotypic associations between CRY2 and two PER3 variants and diurnal preference. The PER3 length polymorphism (rs57875989) was significantly associated with depression in this sample, and individuals homozygous for the PER3 single nucleotide polymorphism (SNP) (rs228697) reported significantly higher anxiety. Our simple model satisfies available experimental knockdown conditions as well as existing data on clock polymorphisms associated with mood. In addition, our model enables us to predict circadian phenotypes (e.g., altered period length, amplitude) associated with mood disorders in order to identify critical effects of clock gene mutations on CRY/BMAL binding and to predict that the intronic SNPs studied represent gain-of-function mutations, causing increased transcription rate. Given the user-friendly structure of our model, we anticipate that it will be useful for further study of the relationships among clock polymorphisms, circadian misalignment, and mood disorders.

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HIV incidence continues to increase in Eastern Europe and Central Asia (EECA), in large part due to non-sterile injection drug use, especially within prisons. Therefore, medication-assisted therapy with opioid agonists is an evidence-based HIV-prevention strategy. The Kyrgyz Republic offers methadone within its prison system, but uptake remains low. Screening, Brief Intervention, and Referral to Treatment (SBIRT) is a framework for identifying people who would potentially benefit from methadone, intervening to identify OUD as a problem and methadone as a potential solution, and providing referral to methadone treatment. Using an SBIRT framework, we screened for OUD in Kyrgyz prisons among people who were within six months of returning to the community (n = 1118). We enrolled 125 people with OUD in this study, 102 of whom were not already engaged in methadone treatment. We conducted a pre-release survey followed by a brief intervention (BI) to address barriers to methadone engagement. Follow-up surveys immediately after the intervention and at 1 month, 3 months, and 6 months after prison release assessed methadone attitudes and uptake. In-depth qualitative interviews with 12 participants explored factors influencing methadone utilization during and after incarceration. Nearly all participants indicated favorable attitudes toward methadone both before and after intervention in surveys; however, interest in initiating methadone treatment remained very low both before and after the BI. Qualitative findings identified five factors that negatively influence methadone uptake, despite expressed positive attitudes toward methadone: (1) interpersonal relationships, (2) interactions with the criminal justice system, (3) logistical concerns, (4) criminal subculture, and (5) health-related concerns.