Mental disorders among adolescents and young adults (ages 10–24) are a significant public health challenge, contributing to long–term morbidity and substantial societal impact. This study analyzes the prevalence, incidence, and years lived with disability (YLDs) of mental disorders in this age group from 1990–2021, with particular attention to the effects of the COVID–19 pandemic during 2019–2021. Using data from the Global Burden of Disease Study 2021, we estimated the prevalence, incidence, and YLDs, along with age–standardized rates (ASR) and 95% uncertainty intervals (95% UIs) for 2021, stratified by sex and age group. Joinpoint regression was employed to calculate annual percentage change (APC) and average annual percentage change (AAPC), along with their corresponding 95% confidence intervals (CIs). In 2021, the global prevalence of mental disorders among adolescents and young adults was 278.98 million (95% UI: 248.61–312.81), with an ASR of 14,764.94 (95% UI: 2804.87–16,908.09). From 2019–2021, there were significant increases in the prevalence, incidence, and YLDs of mental disorders, especially for depressive and anxiety disorders. High–income regions, including North America, Western Europe, and the Asia Pacific, experienced the highest burdens. Globally, the prevalence of mental disorders was higher in males than females among adolescents aged 10–14, but higher in females among those aged 15–24. Joinpoint regression analysis from 1990–2021 revealed an increased burden in depressive disorders, anxiety disorders, bipolar disorder, eating disorders, autism spectrum disorder, conduct disorder, and idiopathic developmental intellectual disability, while decreases were observed in schizophrenia, ADHD, and other mental disorders. This study highlights the significant impact of COVID–19 on the mental health of adolescents and young adults, revealing disparities by region, age, sex, time period, and cohort. It underscores the need for targeted interventions to address the rising mental health burden in this group.

Heart rate variability (HRV) monitoring is increasingly applied in the realm of mental disorders; however, it remains a subject of controversy. This umbrella review summarizes HRV differences between individuals with mental disorders and healthy controls (HCs), as well as changes in HRV before and after treatment in patients with mental disorders. A literature search was conducted using Medline, PubMed, Embase, and the Cochrane Database. Meta-analyses on HRV changes in patients with mental disorders, as well as meta-analyses comparing HCs and patients with mental disorders were included. We computed the summary effect size using random effects models, along with 95% confidence and prediction intervals. We assessed heterogeneity, p value of the largest study, excess significance bias, and small-study effects. Evidence levels were classified as convincing, highly suggestive, suggestive, weak, or not significant. Twenty-one systematic reviews on HRV, covering 19 mental disorders (53 meta-analyses) and 8 treatment modalities (18 meta-analyses), included 442 primary studies and 34,625. For differences between mental disorders and HCs, evidence was suggestive for 7 (13.2%) pooled analyses, indicating decreased HRV in dementia, PTSD, somatic symptom disorders, functional somatic syndromes, and schizophrenia. For other disorders, including autism spectrum disorder, alcohol use disorder, bipolar disorder, generalized anxiety disorder, insomnia, and major depressive disorder, the evidence was weaker and below the suggestive level. For treatment effects, 5 pooled analyses (27.8%) had weak evidence, indicating altered HRV before and after antipsychotic treatment, repetitive transcranial magnetic stimulation treatment, physiotherapy, and psychotherapy. The credibility of HRV evidence in mental disorders varied across HRV variables and diseases. No two diseases exhibited identical altered HRV patterns, highlighting the potential significance of overall HRV profiles in delineating distinct disorders.

Neuropsychiatric disorders are highly heritable and have overlapping genetic underpinnings. Single nucleotide polymorphisms (SNPs) in the gene CACNA1C have been associated with several neuropsychiatric disorders, across multiple genome-wide association studies. A total of 70,711 subjects from 37 independent cohorts with 13 different neuropsychiatric disorders were meta-analyzed to identify overlap of disorder-associated SNPs within CACNA1C. The differential expression of CACNA1C mRNA in five independent postmortem brain cohorts was examined. Finally, the associations of disease-sharing risk alleles with total intracranial volume (ICV), gray matter volumes (GMVs) of subcortical structures, cortical surface area (SA), and average cortical thickness (TH) were tested. Eighteen SNPs within CACNA1C were nominally associated with more than one neuropsychiatric disorder (P < .05); the associations shared among schizophrenia, bipolar disorder, and alcohol use disorder survived false discovery rate correction (five SNPs with P < 7.3 × 10⁻⁴ and q < 0.05). CACNA1C mRNA was differentially expressed in brains from individuals with schizophrenia, bipolar disorder, and Parkinson’s disease, relative to controls (three SNPs with P < .01). Risk alleles shared by schizophrenia, bipolar disorder, substance dependence, and Parkinson’s disease were significantly associated with ICV, GMVs, SA, or TH (one SNP with P ≤ 7.1 × 10⁻³ and q < 0.05). Integrating multiple levels of analyses, we identified CACNA1C variants associated with multiple psychiatric disorders, and schizophrenia and bipolar disorder were most strongly implicated. CACNA1C variants may contribute to shared risk and pathophysiology in these conditions.