The primary aim of trial is to determine the clinical efficacy of in-home decluttering augmentation of group CBT for reducing hoarding severity in adults with HD. The trial takes place in Sweden.

Cognitive behavioral therapy (CBT) is the current evidence-based treatment for HD but the majority of sufferers remain symptomatic after CBT with impairing levels of clutter in their homes. Home visits, with a focus on in-home decluttering, have in previous research been shown to be a promising intervention when combined with CBT. However, augmenting CBT with subsequent home visits has not yet been tested in a randomized controlled trial (RCT). In response to this, in this trial, we aim to investigate the efficacy of a coordinated intervention, consisting of CBT and in-home decluttering for HD, in an RCT. In this trial, 90 participants with HD will initially receive 12 sessions of CBT through a psychiatric outpatient service. After CBT, participants will be randomized to receive either 10 home visits in 10 weeks, or to a wait list condition. Our hypothesis is that augmenting CBT with home visits will lead to a reduction in hoarding symptoms and clutter and improved daily functioning compared to wait list. We will also investigate the cost-economical aspects of the intervention. Results from this trial have the potential to reveal whether in-home decluttering should be added to CBT in order to reduce symptoms of hoarding and improve function in indviduals with HD.

Inclusion Criteria:

1. Age 18 years or older.
2. Hoarding disorder as primary psychiatric condition.
3. Willing and able to understand and complete consent and study procedures.
4. Living in the Stockholm county (Sweden) and within a 1-hour commute by public transport from the social services office.

Exclusion Criteria:

1. Concurrent CBT or having received CBT for HD during the last two years, for a minimum of 8 sessions including active strategies for reducing acquisition and practice of discarding with a qualified therapist or 8 previous in-home decluttering sessions with a qualified social worker.
2. Unable or unwilling to allow study staff into home for home assessment.
3. Animal hoarding or squalid (i.e. extremely unhygienic) home conditions that are deemed to put the personnel at risk during the in-home decluttering.
4. A diagnosis of organic brain disorder, intellectual disability, psychosis, bipolar disorder without stable medication or with symptoms within the last 6 months, anorexia nervosa or alcohol/substance dependence or abuse.
5. Major medical or neurological conditions that increase the risk of participation or that would prevent completing assigned behavioral practice tasks.
6. Immediate risk to self or others, requiring urgent medical attention, such as high suicidality risk.
7. Participant not able to read and communicate in Swedish.
8. Currently at high risk for eviction (for instance having received a "rättelseanmaning" by the housing company or Swedish court).
9. Potential participant lives in the same household as an already included participant.