Who really hoards? Hoarding symptoms in adults with attention-deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD) and healthy controls

Although hoarding disorder (HD) is included in the DSM-5 in the obsessive-compulsive and related disorders chapter, in the last few years, HD has been consistently associated with attention-deficit hyperactivity disorder (ADHD). Some studies on HD patients show higher comorbidity with ADHD than with OCD and some studies on ADHD patients found significant higher rates of HD symptoms compared to the general population. However, the aim of the present study was to be the first direct comparison of the prevalence of HD and HD symptoms across adults with a primary diagnosis of ADHD, OCD and a sample of matched healthy controls (HCs). Methods: 57 adult patients with a primary diagnosis of ADHD and 50 adult patients with a primary diagnosis of OCD were enrolled and matched with 50 HCs. The presence of hoarding disorder and symptoms were assessed though the Saving Inventory Revised (SI-R). Results: ADHD patients showed significantly higher prevalence of HD comorbidity (32.1%) with respect to both OCD patients (8%) and HCs (4%). The prevalence of HD symptoms was also significantly higher in ADHD patients than in both OCD and HCs. Although OCD patients showed a higher prevalence of HD and HD symptoms with respect to HCs, these differences did not reach statistical significance. Conclusion: HD is significantly more comorbid in ADHD patients than in OCD and HCs. A better understanding and definition of the boundaries between HD and the OCD and ADHD spectrum could lead to the development of a more precise treatment approach for hoarding disorder.