Etiological overlap between obsessive‐compulsive disorder and anorexia nervosa: a longitudinal cohort, multigenerational family and twin study

Abstract

Obsessive-compulsive disorder (OCD) often co-occurs with anorexia nervosa (AN), a comorbid profile that complicates the clinical management of both conditions. This population-based study aimed to examine patterns of comorbidity, longitudinal risks, shared familial risks and shared genetic factors between OCD and AN at the population level. Participants were individuals with a diagnosis of OCD (N519,814) or AN (N58,462) in the Swedish National Patient Register between January 1992 and December 2009; their first-, second-and third-degree relatives; and population-matched (1:10 ratio) unaffected comparison individuals and their relatives. Female twins from the population-based Swedish Twin Register (N58,550) were also included. Females with OCD had a 16-fold increased risk of having a comorbid diagnosis of AN, whereas males with OCD had a 37-fold increased risk. Longitudinal analyses showed that individuals first diagnosed with OCD had an increased risk for a later diagnosis of AN (risk ratio, RR53.6), whereas individuals first diagnosed with AN had an even greater risk for a later diagnosis of OCD (RR59.6). These longitudinal risks were about twice as high for males than for females. First-and second-degree relatives of probands with OCD had an increased risk for AN, and the magnitude of this risk tended to increase with the degree of genetic relatedness. Bivariate twin models revealed a moderate but significant degree of genetic overlap between self-reported OCD and AN diagnoses (r a 50.52, 95% CI: 0.26-0.81), but most of the genetic variance was disorder-specific. The moderately high genetic correlation supports the idea that this frequently observed comorbid pattern is at least in part due to shared genetic factors, though disorder-specific factors are more important. These results have implications for current gene-searching efforts and for clinical practice.Key words: Obsessive-compulsive disorder, anorexia nervosa, eating disorders, genetic epidemiology, comorbidity, shared genetic factors (World Psychiatry 2015;14:333-338) An association between obsessive-compulsive disorder (OCD) and eating disorders, particularly anorexia nervosa (AN), has long been observed. In clinical academic settings, these conditions co-occur far more frequently than would be expected by chance, with lifetime prevalence estimates of OCD ranging from 9.5 to 62% in patients with eating disorders (1,2). Similarly, the estimated lifetime prevalence of eating disorders in OCD samples ranges between 11 and 42% (3-5). OCD may, in fact, precede the onset of eating disorders in as many as a quarter of cases, though the relevant studies, with few exceptions (5), have been retrospective (1,2,6,7).Clinically, the comorbidity between OCD and eating disorders poses special challenges. For example, due to the cognitive effects of starvation, very low-weight patients with AN have difficulty engaging in, and benefiting from, cognitive behavioral therapy for OCD.Given these clinical considerations, there is a need to better understand the nature ...

Significant Locus and Metabolic Genetic Correlations Revealed in Genome-Wide Association Study of Anorexia Nervosa

“…First, the strong positive genetic correlations of anorexia nervosa with obsessive-compulsive disorder and neuroticism reinforce clinical and epidemiological observations. AN is commonly comorbid with OCD and twin studies have reported high twin-based genetic correlations (27). High neuroticism in adolescence predicts subsequent onset of AN (1).…”

Do autism spectrum disorder and anorexia nervosa have some eating disturbances in common?

“…Originally, the intention was to include males in the AN group, but at the time of recruitment there were no eligible male patients. However, including males in the study would have given additional information on whether eating behaviours frequently seen in ASD are even more common in male patients with AN [34, 35]. Furthermore it is a limitation that the instruments SWEAA and AQ were self-report measurements.…”

Genetics of Anorexia Nervosa

“…Replicated heritability estimates for AN have ranged between 48%−74% depending on the definition of AN used [*5]. Twin studies have also suggested there is shared genetic risk between AN and multiple psychiatric phenotypes including other eating disorders [9], obsessive compulsive disorder [10], major depression, and suicide attempts [11]. Although family and twin studies provided initial evidence of the role of genetic factors in AN, these methods cannot identify which genetic variants are involved in risk.…”