Review of studies finds children of parents with mental disorders at increased risk

Children of people with mental illnesses are at higher risk of suffering the same and different disorders, a new review of hundreds of studies suggests. This is due to a combination of genetic and environmental factors that tend to encourage these ailments, which manifest more frequently in some families than others. The review of 211 studies, which was recently published in the scientific journal World Psychiatry, attempts to quantify this increased risk by surveying data on some three million children who had at least one affected parent and 20 million people without family diagnoses of mental illness as a control.

The authors of the review estimate that, on average, about one in two children of people with anxiety, bipolar disorder or depression will suffer from their parent’s condition or another mental illness. More than a third of the children of parents with an addiction and one in six with psychosis will also have a mental disorder. In terms of the increased risk of suffering from the same disorder as their parent, if the parent has attention deficit disorder, the chances of their offspring suffering from it are eight times higher. In the case of bipolar disorder, the risk is multiplied fivefold, and in the case of addictions, depression or anxiety, by a factor of two. When looking at combined risks, children of parents with psychosis have 5.8 times the risk of suffering from the same disease and 2.6 times the risk of suffering from some other disease, with similar figures for bipolar disorder. The results presented in the review are in line with previous studies examining twins, which show that genetically identical individuals have as much as a 77% shared risk of psychosis, with a 76% shared risk for bipolar disorder, 40% for anxiety, and 34% for depression.

At a press conference organized by Science Media Center (SMC) Spain, Joaquim Raduà, a psychiatrist at Hospital Clínic de Barcelona and a co-author of the study, highlighted the value of this work in “identifying a subgroup of the population in relatives of people at higher risk in order to apply specific preventive treatments.” The study warns that the search for symptoms among children of those affected by mental ailments is not a routinely applied practice — something researchers say should change. “This prevention should be transdiagnostic,” Raduà says, acknowledging that both genetic and environmental factors seem to favor the appearance of various disorders.

Although it is not possible to know whether specific preventive measures have forestalled the development of a given disorder in a given individual, population studies indicate that these measures are indeed effective. Researchers have observed that interventions in schools that sought to prevent depressive or anxiety symptoms have not proven effective, however, and in fact may even cause more harm. For this reason, the authors stress the importance of identifying those with the greatest risk in order to initiate early and effective interventions.

Among the measures proposed, many have to do with avoiding factors that increase the risk of a disease being triggered, such as the use of cannabis or other substances, or poor metabolic health and obesity, which can be prevented by exercise and proper nutrition. Some factors such as exposure to traumatic events or extreme poverty or social isolation also favor the onset of disorders.

Alberto Ortiz Lobo, a psychiatrist at Madrid’s Hospital Universitario La Paz, in statements made to SMC Spain, is critical of the study’s conclusions. “The results reveal that 55% of the offspring of parents diagnosed with any mental disorder will develop some type of mental disorder during their lifetime, with a confidence interval of no less than 7% to 95%,” he points out. In his opinion, these imprecise figures do not allow “any genetic assessment to be made, as the authors seem to suggest, since the association between diagnoses of mental disorders and biological inheritance has not been demonstrated.” For Ortiz Lobo, it is more important and effective to address social determinants like child abuse, low educational levels and poverty.

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