Study data published in the Journal of Child Psychology and Psychiatry support the existence of a general dimension of psychopathology, known as the p factor. Significant genetic overlap was observed between p in childhood and subsequent risk for diagnosis of psychiatric disorders in adulthood.
Investigators at King’s College London and University College London in the UK abstracted data from 7026 twin pairs in the Twins Early Development Study (TEDS). Surveys were administered at ages 7, 9, 12, and 16 years, capturing child-, parent-, and teacher-rated measures of behavioral problems, including depressive traits, emotional problems, peer problems, autism traits, hyperactivity, antisocial behavior, conduct problems, and psychopathic tendencies.
Multivariate twin models estimated common genetic and environmental influences on p. Further, a Cholesky decomposition of parent-rated p components was performed to assess the stability of genetic and environmental influences over time. A genetic p factor was created on the basis of 8 polygenic risk scores for psychiatric disorders. Genetic p was compared across 7026 unrelated genotyped TEDS participants to assess the relationship between childhood p and polygenic predisposition to adult psychiatric disorders.
Across age groups and child-, teacher-, and parent-rated measures, behavior problems correlated both phenotypically and genetically. Common pathway twin models showed substantial heritability for the p factor (50%-60%), which manifested consistently across age groups and raters. However, unique genetic and environmental contributions outside of p were also observed. Autism traits, conduct problems, antisocial behavior, and psychopathic tendencies loaded the highest on the parent- and teacher-rated p factor, whereas emotional problems, depression, and anxiety loaded the highest on the child-rated p factor.
Genetic effects on psychopathology remained stable across childhood and adolescence, as age-to-age genetic correlations ranged from 49% to 78%. A general polygenic p score for adult psychiatric disorders was significantly associated with phenotypic p scores in childhood, predicting 0.3% to 0.9% of variance across ages and raters.
Limitations included changes in available measures and informants, which introduced variability into results. Future studies are necessary to determine whether correlated factor models have a specific genetic basis.
The investigators concluded, “In sum, these analyses provide further evidence that a common genetic substrate permeates the landscape of psychopathology, across measures, ages and raters.”
Allegrini AG, Cheesman R, Rimfeld K, et al. The p factor: genetic analyses support a general dimension of psychopathology in childhood and adolescence [published online September 20, 2019]. J Child Psychol Psychiatry. doi:10.1111/jcpp.13113