Dataset Information

Socioeconomic sequelae of drug abuse in a Swedish national cohort.

ABSTRACT:

Background

Drug abuse is frequently associated with negative sequelae such as reduced socioeconomic functioning. The extent to which these associations are attributable to a causal role of the disorder versus confounding factors that increase risk for both drug abuse and negative socioeconomic outcomes is unclear.

Methods

Drug abuse cases were identified using Swedish national medical, pharmacy, and criminal registers. Applying Cox proportional hazard models, we tested the association between drug abuse and four outcomes: early retirement, social assistance, unemployment, and income at age 50. We used co-relative models to determine whether familial confounding factors accounted for observed associations.

Results

In models adjusted for birth year, education, and early onset externalizing behavior, drug abuse was strongly associated with early retirement (hazard ratios [HR] = 5.13-6.28), social assistance (HR = 6.74-7.89), and income at age 50 (beta = -0.19 to -0.12); it was more modestly associated with unemployment (HR = 1.05-1.20). For social assistance and income (both sexes), and early retirement (women only), a model in which the association was partly attributable to familial factors fit the data well; residual associations support a partially causal role of drug abuse. For unemployment and early retirement among men, there was little evidence of familial confounding.

Conclusions

The negative socioeconomic sequelae of drug abuse are likely due in part to familial confounding factors in conjunction with a causal relationship and/or unmeasured non-familial confounders. Relative contributions from distinct mechanisms differed across socioeconomic outcomes, which could have implications for understanding the potential impact of prevention and intervention efforts.

SUBMITTER: Edwards AC

PROVIDER: S-EPMC7293925 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Using Swedish nationwide registry data, the authors investigated genetic and environmental risk factors in the etiology of drug abuse by twin sibling modeling. The authors followed up with epidemiological analyses to identify shared environmental influences on drug abuse.Drug abuse was defined using public medical, legal, or pharmacy records. Twin and sibling pairs were obtained from the national twin and genealogical registers. Information about sibling pair residence within the same household, small residential area, or municipality was obtained from Statistics Sweden. The authors predicted concordance for drug abuse by years of co-residence until the older sibling turned 21 and risk for future drug abuse in adolescents living with parental figures as a function of family-level socioeconomic status and neighborhood social deprivation.The best twin sibling fit model predicted substantial heritability for drug abuse in males (55%) and females (73%), with environmental factors shared by siblings operating only in males and accounting for 23% of the variance in liability. For each year of living in the same household, the probability of sibling concordance for drug abuse increased 2%-5%. When not residing in the same household, concordance was predicted from residence in the same small residential area or municipality. Risk for drug abuse was predicted both by family socioeconomic status and neighborhood social deprivation. Controlling for family socioeconomic status, each year of living in a high social deprivation neighborhood increased the risk for drug abuse by 2%.Using objective registry data, the authors found that drug abuse is highly heritable. A substantial proportion of the shared environmental effect on drug abuse comes from community-wide rather than household-level influences. Genetic effects demonstrated in twin studies have led to molecular analyses to elucidate biological pathways. In a parallel manner, environmental effects can be followed up by epidemiological studies to clarify social mechanisms.