Long-term changes of hoarding symptoms among adults with attention-deficit/hyperactivity disorder (ADHD) treated with methylphenidate

Hoarding disorder (HD) has been consistently linked to attention-deficit/hyperactivity disorder (ADHD), and ADHD patients show high rates of HD comorbidity. However, no studies have investigated the effects of ADHD medications on hoarding symptoms in patients with a primary diagnosis of ADHD. Thus, the aim of this naturalistic study was to investigate the long-term changes of hoarding symptoms among adult ADHD patients after at least one year of treatment with methylphenidate. METHODS: 60 newly diagnosed adult ADHD outpatients underwent a psychometric assessment which included hoarding symptoms (measured through the Saving Inventory-Revised Scale, SI-R) and a cognitive assessment focused on attentional and executive functions, before and after at least one year of treatment with methylphenidate. RESULTS: Hoarding symptoms showed a significant pre-post treatment reduction (median 32 [20; 37] and 24 [13; 35.75] respectively; p < .001). The improvement was significant for the SI-R subscales of excessive acquisition and clutter, but not for the difficulty discarding subscale. Most of the patients (71.6 %) showed hoarding symptoms reduction, but a subgroup of subjects (5 %) didn't show any change or (23.4 %) showed a slight worsening. Hoarding improvement was at least partially predicted by ADHD symptoms improvement. CONCLUSION: With methylphenidate treatment, hoarding symptoms improved over time in the majority of the study participants. The improvement was significant for clutter and excessive acquisition symptoms, but not for the core hoarding symptom of difficulty discarding. Further controlled studies on larger samples of ADHD patients with comorbid HD are needed to elucidate the potential effect of methylphenidate in this population.