Hoarding and obsessive–compulsive behaviours in frontotemporal dementia: Clinical and neuroanatomic associations

Background: Hoarding and obsessive-compulsive behaviours (OCB) are well documented symptoms in frontotemporal dementia (FTD). While contemporary models consider hoarding and obsessive-compulsive disorder distinct, the related behaviours have not been separately examined in patients with FTD, and the neuroanatomical correlates of hoarding in patients with FTD have not been previously examined (American Psychiatric Association, 2013; Grisham and Baldwin, 2015; Mataix-Cols et al., 2010). Methods: Patients with FTD who were evaluated between 2004 and 2018 at our centre were included. Cortical thickness and subcortical volumetric analyses were completed on available T1 high resolution anatomic scans using FreeSurfer. Results: Eighty-seven patients met inclusion criteria, and 49 had scans available for quantitative MRI volumetric analysis. New hoarding behaviours were present in 29% of patients and were more common in the semantic variant subtype of FTD, while 49% of individuals had new or increased OCB. Hoarding behaviours were associated with decreased thickness in a factor comprised of left temporal, insular and anterior cingulate cortices. The presence of OCB was predicted by reduced cortical thickness and volumes in a factor comprised of the anterior cingulate and subcortical volumes in the bilateral amygdala and hippocampus. OCB were associated with greater right temporal cortical thickness in comparison to patients with hoarding. Discussion: The association of the semantic variant with hoarding, together with the observed associations between left temporal atrophy and hoarding indicate that degeneration of the left temporal lobe has a role in the emergence of hoarding in FTD. As in current models of Hoarding disorder and Obsessive–Compulsive disorder, our results suggest that in patients with FTD, hoarding and OCB are clinically and anatomically partially dissociable phenomenon. The results may also help to further elucidate the cognitive processes and neural networks contributing to Hoarding disorder and Obsessive–Compulsive disorder in persons without dementia.