Morbid risk of alcohol and cannabis use disorders among relatives of probands in a Nigerian Psychiatric Hospital

Abstract

The generation of genetic epidemiological data in Africa to drive public education on the biological basis of substance use disorders  (SUDs), which has been popularly misconstrued as a moral failure, has become imperative, in order to encourage access to formal care by patients. This study aimed to determine the morbid risks of SUDs among the first-degree relatives (FDRs) of probands with alcohol use disorder (AUD) and cannabis use disorder (CUD), in comparison with the families of healthy control group. The study elicited information on the morbid risk of SUDs among FDRs of probands with AUD and CUD and relatives of a healthy control group through direct interview or by proxy interview of relatives using the Family Interview for Genetic Studies (FIGS). The best-estimate method was used for the diagnosis in the relatives of the probands and a comparison group. Logistic regression was used to estimate the odds ratios (OR) and 95% confidence intervals (CI) for the differences in proportion of the affected versus unaffected FDRs, while the Weinberger method was used to estimate morbid risks. The morbid risks among FDRs of probands with AUD and CUD were 17.5(95% CI, 17.1-17.9) and 11.6(11.2-12.0), respectively, in comparison with 7.8(95% CI, 7.6-8.0) and 5.7(95% CI, 5.5-5.9), respectively, for the FDRs of the controls. The increased  familial risk of SUDs among FDRs of probands with alcohol and cannabis use disorders in an African population is similar to that in the Western population. Therefore, preventive strategies involving the family may be useful.