A cross ancestry genetic study of psychiatric disorders from India.

Genome-wide association studies across diverse populations may help validate and confirm genetic contributions to risk of disease. We estimated the extent of population stratification as well as the predictive accuracy of polygenic scores (PGS) derived from European samples to a data set from India. We analysed 2685 samples from two data sets, a population neurodevelopmental study (cVEDA) and a hospital-based sample of bipolar affective disorder (BD) and obsessive-compulsive disorder (OCD). Genotyping was conducted using Illumina's Global Screening Array. Population structure was examined with principal component analysis (PCA), uniform manifold approximation and projection (UMAP), support vector machine (SVM) ancestry predictions, and admixture analysis. PGS were calculated from the largest available European discovery GWAS summary statistics for BD, OCD, and externalizing traits using two Bayesian methods that incorporate local linkage disequilibrium structures (PGS-CS-auto) and functional genomic annotations (SBayesRC). Our analyses reveal global and continental PCA overlap with other South Asian populations. Admixture analysis revealed a north-south genetic axis within India (FST 1.6%). The UMAP partially reconstructed the contours of the Indian subcontinent. The Bayesian PGS analyses indicates moderate-to-high predictive power for BD. This was despite the cross-ancestry bias of the discovery GWAS dataset, with the currently available data. However, accuracy for OCD and externalizing traits was much lower. The predictive accuracy was perhaps influenced by the sample size of the discovery GWAS and phenotypic heterogeneity across the syndromes and traits studied. Our study results highlight the accuracy and generalizability of newer PGS models across ancestries. Further research, across diverse populations, would help understand causal mechanisms that contribute to psychiatric syndromes and traits.

Long-term impact of the COVID-19 pandemic on obsessive-compulsive disorder.

There is limited data on the long-term effect of the COVID-19 pandemic on obsessive-compulsive disorder (OCD). We report on the course of a cohort of individuals with OCD followed-up over a period of one year during the first wave of the COVID-19 pandemic in India. A cohort of 240 individuals registered at a specialty OCD clinic was regularly followed-up using standardized rating tools at three months, six months, and one year into the onset of the COVID-19 pandemic in India. These were compared with clinical ratings recorded in a comparable historical cohort of 207 individuals with OCD, followed up during a non-pandemic year. The pandemic and non-pandemic (historical control) cohorts did not differ in illness severity and rate of relapse. It was found that COVID-19-related anxiety declined over time. Among those patients who were treatment responders prior to the pandemic, COVID-19-related anxiety and non-adherence to medication predicted a relapse of symptoms. Contrary to our expectations, the rate of relapse and illness trajectory in the pandemic cohort did not differ from the non-pandemic cohort, suggesting that the pandemic did not impact our largely medication-adherent cohort. Adherence to treatment seemed to have a protective effect during the pandemic.