Prevalence of intellectual disability in India: A meta-analysis

Validity and reliability of the new NIMHANS intellectual disability screening instrument (NID-Screener) for children and adolescents in India

INTRODUCTION

There is a gap in tools specifically designed for assessing Intellectual Disability (ID) in Indian settings. To address this, the NIMHANS intellectual disability screening instrument (NID-Screener) was developed by the Department of Child and Adolescent Psychiatry, National Institute of Mental Health and Neuro Sciences.

METHODS

Ten non experts/language and ten experts rated face and content validity of NID-Screener respectively. Content validity was measured by Content Validity Ratio, Content Validity Indices (I-CVI, S-CVI) and Modified Kappa statistics. Construct validity was calculated by performing Exploratory Factor Analysis(EFA) on responses from 275 parent(s)/guardian(s) of children and adolescents (6-17 years). Criterion Validity was tested against Brief Intellectual Disability Scale (BIDS) and Clinical Diagnosis by Child and Adolescent Psychiatrist. Kappa Statistics was used to calculate inter - method and inter-Rater Reliability. Cronbach's alpha was used to assess Internal Consistency. This study was approved by NIMHANS ethics committee.

RESULTS

Findings revealed that NID-Screener has good face and content validity (S-CVI/Average = 0.917). Criterion Validity was excellent (Kappa Value=0.862, p-value<0.001) when compared with BIDS. Sensitivity and specificity were found to be 84.7 %, 89 % respectively against Clinical Diagnosis. On EFA, only one underlying factor with Eigen value > 1 was identified (55.8 % of total variance). Kappa value was found to be 0.971 and 0.942 for inter- rater and inter -method reliability respectively(p-value<0.001). NID-Screener has good internal consistency [Cronbach's alpha = 0.841].

CONCLUSIONS

NID-Screener is a reliable and valid tool for screening ID among children and adolescents in India, facilitating its early detection through diagnostic assessments and subsequent interventions.

De novo variants underlying monogenic syndromes with intellectual disability in a neurodevelopmental cohort from India

The contribution of de novo variants as a cause of intellectual disability (ID) is well established in several cohorts reported from the developed world. However, the genetic landscape as well as the appropriate testing strategies for identification of de novo variants of these disorders remain largely unknown in low-and middle-income countries like India. In this study, we delineate the clinical and genotypic spectrum of 54 families (55 individuals) with syndromic ID harboring rare de novo variants. We also emphasize on the effectiveness of singleton exome sequencing as a valuable tool for diagnosing these disorders in resource limited settings. Overall, 46 distinct disorders were identified encompassing 46 genes with 51 single-nucleotide variants and/or indels and two copy-number variants. Pathogenic variants were identified in CREBBP, TSC2, KMT2D, MECP2, IDS, NIPBL, NSD1, RIT1, SOX10, BRWD3, FOXG1, BCL11A, KDM6B, KDM5C, SETD5, QRICH1, DCX, SMARCD1, ASXL1, ASXL3, AKT3, FBN2, TCF12, WASF1, BRAF, SMARCA4, SMARCA2, TUBG1, KMT2A, CTNNB1, DLG4, MEIS2, GATAD2B, FBXW7, ANKRD11, ARID1B, DYNC1H1, HIVEP2, NEXMIF, ZBTB18, SETD1B, DYRK1A, SRCAP, CASK, L1CAM, and KRAS. Twenty-four of these monogenic disorders have not been previously reported in the Indian population. Notably, 39 out of 53 (74%) disease-causing variants are novel. These variants were identified in the genes mainly encoding transcriptional and chromatin regulators, serine threonine kinases, lysosomal enzymes, molecular motors, synaptic proteins, neuronal migration machinery, adhesion molecules, structural proteins and signaling molecules.

Age- and Gender-Specific Prevalence of Intellectually Disabled Population in India

Intellectual disability in India is substantially under-reported, especially amongst females. This study quantifies the prevalence and gender bias in household reporting of intellectual disability by estimating the age-and-gender specific prevalence of the intellectually disabled by education, Socio-Demographic Index (SDI) score, place of residence, (rural/urban) and income of household head. We estimated prevalence (per 100,000) at 179 (95% CI: 173 to 185) for males and 120 (95% CI: 115 to 125) for females. Gender differences declined sharply with increased education, was higher for lower ages and low income and varied little by state development. Under-identification and under-reporting due to stigma are two plausible reasons for the gender differences in prevalence that increase with age.

Prevalence of mental disorders in South Asia: A systematic review of reviews

Mental disorders are increasing in South Asia (SA), but their epidemiological burden is under-researched. We carried out a systematic umbrella review to estimate the prevalence of mental disorders and intentional self-harm in the region. Multiple databases were searched and systematic reviews reporting the prevalence of at least one mental disorder from countries in SA were included. Review data were narratively synthesised; primary studies of common mental disorders (CMDs) among adults were identified from a selected subset of reviews and pooled. We included 124 reviews. The majority (n = 65) reported on mood disorders, followed by anxiety disorders (n = 45). High prevalence of mental disorders and intentional self-harm was found in general adult and vulnerable populations. Two reviews met our pre-defined criteria for identifying primary studies of CMDs. Meta-analysis of 25 primary studies showed a pooled prevalence of 16.0% (95% CI = 11.0-22.0%, I 2 = 99.9%) for depression, 12.0% (5.0-21.0%, I 2 = 99.9%) for anxiety, and 14.0% (10.0-19.0, I 2 = 99.9%) for both among the general adult population; pooled estimates varied by country and assessment tool used. Overall, reviews suggest high prevalence for mental disorders in SA, but evidence is limited on conditions other than CMDs.