Adults were more likely to have depression if they had a parent with a drug or alcohol addiction that caused problems in the family, a study showed.
The increased risk for depression remained even after investigators accounted for other factors that might have increased the risk for depression.
"These findings underscore the intergenerational consequences of drug and alcohol addiction and reinforce the need to develop interventions that support healthy childhood development to prevent ongoing patterns of addiction and prevention," Esme Fuller-Thomson, Ph.D., and her colleagues at the University of Toronto wrote in Psychiatry Research (2013 [doi: 10.1016/j.psychres.2013.02.024]). They noted that 7.3 million children under age 18 live with a parent who misuses alcohol and 2.1 million children live with a parent who abuses illicit drugs in the United States, based on previous research.
The investigators analyzed the responses of 6,268 adults from Saskatchewan in the 2005 Canadian Community Health Survey. A total of 15.2% of the responders had been exposed to a parent with addiction, based on an affirmative answer to whether either of their parents drank alcohol or used drugs so often that it caused problems in their family.
Meanwhile, 5.6% of the sample were classified as depressed based on the Composite International Diagnostic Interview - Short Form (using DSM-III-R criteria). Those with at least a 90% probability for a major depressive episode lasting at least 2 weeks within the past year were considered depressed.
Before any confounders beyond age, sex, and race (white or minority) were considered, adults exposed to a parent with addiction had more than double the odds of having depression, compared with peers with nonaddicted parents (OR = 2.27; 95% CI, 1.74-2.96). Then the researchers added four categories of confounders to their model: adverse childhood experiences, responders’ socioeconomic status as adults, life stressors in adulthood, and adult health behaviors.
After investigators accounted for these factors, adults who had a parent with an alcohol or drug addiction remained at higher risk for depression, with 1.69 greater odds than peers whose parents did not have these addictions (OR = 1.69; 95% CI, 1.25-2.28). Although women were more likely to have depression than men across the full sample, no significant influence for gender was found on the link between parental addiction and adult depression.
The confounders of adult health behaviors included alcohol consumption , smoking status, body mass index (BMI), and physical activity. The responders’ adult socioeconomic status considered their highest level of education and their household income, because depression is associated with poverty and a lower education level.
Adverse childhood experiences included parental divorce, parental unemployment (for at least a period of time), and physical abuse. Adult responders’ other life stressors included in the analysis were self-reported daily stress level, having a chronic condition, and marital status (married or single/separated/divorced/widowed).
Adding each of these categories did not change the initial odds much, except the addition of adverse childhood experiences, which dropped the adults’ odds (without the other categories) to 1.67 times greater depression risk among those with an addicted parent compared with those with a nonaddicted parent (OR = 1.67; 95% CI, 1.25-2.24). The reduction in odds after the addition of adverse childhood experiences to the overall model just missed statistical significance, the authors reported, leading this study’s findings to vary from the findings of past studies, "which found that co-occurring adverse childhood experiences, such as abuse, accounted for the entire association between parental addiction and depression."
"Moreover, the number of adversities experienced in childhood was independently associated with the increased odds of depression," Dr. Fuller-Thomson and colleagues reported. They also found increased daily stress, having at least one chronic illness and being single, to independently predict depression.
Study limitations included a lack of information on parental depression, the sex of the addicted parent, prenatal exposure to drugs or alcohol, and early environmental or genetic factors that previously have all been shown to increase the risk of adult depression. However, the link between parental addiction and adult depression even after the other factors in this study were accounted for point to a possible "susceptibility to a set of genes common to both depression and addiction," the authors suggested.
The only funding source noted was internal support from the first author’s Sandra Rotman Endowed Chair in Social Work. No other disclosures were reported.