Although clinical evidence has shown a link between ADHD and eating disorders, there are limited data available on whether ADHD symptoms may impact treatment adherence and outcomes. This study evaluated whether the presence of ADHD symptoms in individuals with eating disorders affects therapy outcomes after cognitive behavioural therapy for the treatment of eating disorders, as well as adherence to treatment. The impact of ADHD symptoms on long-term therapy outcomes, and whether the severity of the eating disorder impacted ADHD symptoms and treatment outcomes, was also assessed.

A total of 136 women treated for an eating disorder at Bellvitge University Hospital, Barcelona, Spain between April 2009 and January 2011 were included in this retrospective analysis. Seventy-two women completed treatment sessions, while 64 did not and were considered dropouts. The ADHD Self-Report Scale (ASRS v1.1) for ADHD symptoms and the Eating Disorders Inventory (EDI-2) for assessment of eating symptomatology were conducted at baseline. All participants received cognitive behavioural therapy for their particular eating disorder and were re-evaluated after treatment and categorised according to the Diagnostic and Statistical Manual of Mental Disorders – 5th Edition criteria as having achieved full remission,* partial remission^† or non-remission.^‡ Longitudinal follow-up was conducted during an average 8.8-year period.

Baseline demographics were similar between participants selected for the study and those that were excluded. The dropout rate in the total sample was 47.0%. A total of 11.8% of participants were classified as having non-remission; partial remission was observed in 18.4% of participants and full remission was observed in 22.8% of participants. Within the sub-sample of individuals who completed treatment (n = 72), 43.1%, 34.7% and 22.2% were classified as having full remission, partial remission and non-remission, respectively.

Positive screening for ADHD symptoms was related to higher eating disorder symptomatology (standardised coefficient B = 0.41; p = 0.001; 95% confidence interval [CI] 0.26–0.55), which in turn contributed to the increased dropout (B = 0.15; p = 0.041; 95% CI 0.03–0.33) and worse treatment outcomes (B = 0.18; p = 0.041; 95% CI 0.01–0.35). No direct effect was found between the ASRS positive screening with the risk of dropout (B = –0.08; p = 0.375) and worse treatment outcome (B = –0.07; p = 0.414). Positive screening for ADHD symptoms at baseline had no impact on eating disorders over the long term.

Limitations of the study included the retrospective study design and the use of a self-reporting instrument to measure the frequency of ADHD symptoms, which may lead to overestimation of symptoms. Furthermore, this analysis only included women, and objective measures were not available after follow-up.

To summarise, this study suggests a higher risk for treatment dropout and worse outcomes in individuals with more severe eating disorder symptoms. These results suggest the importance of identifying specific treatment approaches for individuals with ADHD and more severe eating disorder symptoms.

Read more about ADHD and eating disorders here

*Total absence of symptoms meeting criteria for at least 4 consecutive weeks
^†Substantial symptomatic improvement, but with residual symptoms
^‡Poor outcomes