Twin study finds higher risk of suicidality among adolescents with body dysmorphic symptoms, which is largely due to genetic factors

A large twin study found that adolescents and young adults with body dysmorphic symptoms had an increased risk of suicidal thoughts and suicide attempts. The study, published in the journal Psychological Medicinefurther found that this heightened risk was largely explained by shared genetic factors.

Body dysmorphic disorder (BDD) is a clinical condition that involves a concern with a perceived defect in one’s appearance that is either nonexistent or unnoticeable to others. These persistent thoughts seriously impact a sufferer’s quality of life, and the condition is associated with high rates of suicidality. BDD tends to emerge during adolescence, and yet, most studies investigating the link between BDD and suicidality have been conducted among adult samples. Study author Georgina Krebs and her colleagues emphasize the need to extend this research by studying community samples and younger people.

“As a clinical psychologist, I specialize in working with young people with obsessive-compulsive and related disorders, which includes BDD. I have seen first-hand the devastating impact that BDD can have on people’s lives, and the high rates of suicidality experienced by this group,” said Krebs, an associate professor at University College London and honorary consultant clinical psychologist at Camden and Islington NHS Foundation Trust.

“We wanted to gauge how much of the relationship between BDD and suicidality is due to a shared genetic vulnerability, and how much of the relationship is environmentally mediated. From a clinical perspective, we often view suicidality as being a functional consequence of the psychosocial burden of living with BDD. However, the genetic literature shows that many mental health difficulties have common genetic influences, which led us to expect that genetic factors would explain some of the relationship between BDD and suicidally.”

Krebs and her team obtained data from a longitudinal twin study called the Child and Adolescent Twin Study in Sweden, which included all twins born in Sweden since July 1992. Their analysis focused on 6,027 participants who completed questionnaires at age 18, and a separate cohort of 3,454 participants who completed questionnaires at age 24. All twins completed a measure of BDD symptoms and measures of suicide attempts, anxiety, and depression. At age 18, parents were also asked whether their child had ever harmed themselves or attempted suicide.

An analysis of the results revealed significant findings. For both the 18- and 24-year-olds, participants who met the cut-off for probable body dysmorphic disorder had a greater likelihood of suicidal ideation or suicidal behaviors — such that about a quarter of them reported having attempted suicide (vs. 5). % for those below the cut-off).

When BDD symptoms were modeled as continuous scores, higher symptoms were related to all measures of suicidality. The strength of these effects dropped but remained significant when controlling for depression and anxiety, with the exception of parent reports of adolescents’ suicide attempts at age 18. The researchers say this suggests that BDD symptoms are an “independent risk factor for suicidality”, beyond depressive symptoms or anxiety.

According to the study authors, the findings suggest that suicidal thoughts are present at an alarmingly early stage of the illness. Studies estimate that BDD tends to emerge around ages 16–17, and according to the parent reports in this study, 18-year-olds with probable BDD were seven times more likely to attempt suicide than those without. Krebs and her colleagues also note that parents tended to underestimate the occurrence of suicidality in their children, a concerning finding that mirrors previous evidence that suicidality often goes unnoticed by parents.

“BDD appears to be associated with high rates of suicidality adolescents and young adults, with about one in four of those with clinically significant BDD symptoms reporting that they have attempted suicide,” Krebs told PsyPost. “This is clearly very important for clinicians to be aware of when thinking about assessment, ongoing monitoring and support, and treatment for individuals with BDD.”

Notably, twin studies allow researchers to separate environmental factors from genetic factors by comparing monozygotic (MZ) twins (100% shared genes) and dizygotic (DZ) twins (50% shared genes). By comparing within-pair correlations for the two types of twins, the researchers found that genetic factors accounted for a large portion of the covariance between BDD symptoms and suicidality — 72.9% at age 18 and 77.7% at age 24.

The study authors said that future efforts to pinpoint the genetic variants associated with BDD might provide insight into the biological processes implicated in suicidality. Still, non-shared environmental factors accounted for a significant portion of the covariance, accounting for 27.1% at age 18 and 22.3% at age 24. If future studies can unearth these environmental influences, this may help inform possible treatment and prevention options.

“About three-quarters of the association between BDD symptoms and suicidality is explained by genetic factors, and about one-quarter is explained by environmental factors (specifically, ‘non-shared’ environmental factors). Further understanding these environmental mechanisms is crucial, as it may reveal an opportunity for intervention,” Krebs said.

A notable limitation of the study was the use of self-report measures to identify probable cases of BDD, which is less reliable than clinical assessments. The authors said that it would be interesting for future studies to try to replicate these findings among BDD patients and their relatives.

“In addition, questions about BDD and suicidality were asked at the same point in time, which means that we could not determine whether BDD symptoms or suicidality came first,” Krebs noted. “We need longitudinal studies to determine the direction of effect and test the notion that suicidality often occurs as a consequence of having BDD.”

“This study highlights the clinical significance of BDD, but concerningly we know that BDD often goes undetected and untreated,” she added. “Increasing awareness of BDD, and improving access to evidence-based treatments for this disorder, are very important clinical priorities.”

The study, “The association between body dysmorphic symptoms and suicidality among adolescents and young adults: a genetically informative study”, was authored by Georgina Krebs, Lorena Fernández de la Cruz, Frühling V. Rijsdijk, Daniel Rautio, Jesper Enander, Christian Rück, Paul Lichtenstein, Sebastian Lundström, Henrik Larsson, Thalia C. Eley, and David Mataix-Cols.

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