The first genome-wide association study of internet addiction; Revealed substantial shared risk factors with neurodevelopmental psychiatric disorders.

BACKGROUND: Internet addiction disorder (IAD) is listed as a disorder requiring further studies in the diagnostic and statistical manual of mental disorders (DSM-V). Psychological studies showed significant co-morbidity of IAD with depression, alcohol abuse, and anxiety disorder. Etiology and genetic bases of IAD are unclear. AIMS: Present study aimed to investigate the genetic, psychological, and cognitive bases of a tendency to internet addiction. METHODS AND PROCEDURES: DNA was extracted from blood samples of IADs (N = 16,520) and 18,000 matched non-psychiatric subjects. Genotyping for the subjects was performed using SNP Array. Psychological, neuropsychological, and neurological characteristics were conducted. OUTCOMES AND RESULTS: Seventy-two SNPs in 24 genes have been detected significantly associated with IAD. Most of these SNPs were risk factors for psychiatric disorders. Most similarity detected with autism spectrum disorder, bipolar disorder and schizophrenia. Higher anxiety, stress, and neuroticism and deficits in working memory, attention, planning, and processing speed were detected in IADs. CONCLUSIONS: This study is the first genome-wide association study of IAD that showed strong shared genetic bases with neurodevelopmental disabilities and psychiatric disorders. IMPLICATIONS: Genetic risk factors in IADs may cause several cognitive and neurodevelopmental brain function abnormalities, which lead to excessive Internet usage. It may suggest that IAD could be a marker for vulnerability to developmental psychiatric disorders.

Neuregulin1 types mRNA level changes in autism spectrum disorder, and is associated with deficit in executive functions.

BACKGROUND: Autism spectrum disorder (ASD) is a pediatric heterogeneous psychiatric and neurodevelopmental disorder with social and communication deficits, language impairment and ritualistic or repetitive behaviors. ASD has significant genetic bases but candidate genes and molecular mechanisms of disorder are not clarified. Neuregulin1 (NRG1) gene, located in 8p12 is involved in development of central nervous system and was indicated as candidate gene in schizophrenia. METHODS: mRNA level of types I, II and III of NRG1 gene were studied in peripheral blood of 1540 ASD patients (IQ > 70) and 1490 control children by quantitative Real Time PCR. Also three domains of executive functions (working memory, response inhibition and vigilance) were examined in all subjects. FINDINGS: All three types were significantly down regulated in ASD patients. Significant deficiencies in executive functions (EF) were found in ASD patients. EF deficiencies mostly were associated with down expression of mRNA level of types I and III. Also correlations were found between NRG1 expression with gender and severity of ASD symptoms. INTERPRETATIONS: Findings primarily have been suggested involvement of NRG1 in etiology of ASD. Also correlation of NRG1 mRNA level with EF deficiencies could shed lights on EF mechanisms and may suggest targeted treatments to improve particular executive functions. FUND: Young researchers and elites club funded the project due to the annual grant of special talents of Club that gave to Arvin Haghighatfard.