Late Life Major Depressive Disorder (LLD) and Hoarding Disorder (HD) are common in older adults with prevalence estimates up to 29% and 7%, respectively. Both LLD and HD are characterized by executive dysfunction and disability. There is evidence of overlapping neurobiological dysfunction in LLD and HD suggesting potential for compounded executive dysfunction and disability in the context of comorbid HD and LLD. Yet, prevalence of HD in primary presenting LLD has not been examined and potential compounded impact on executive functioning, disability, and treatment response remains unknown. Thus, the present study aimed to determine the prevalence of co-occurring HD in primary presenting LLD and examine hoarding symptom severity as a contributor to executive dysfunction, disability, and response to treatment for LLD.

Eighty-three adults ages 65-90 participating in a psychotherapy study for LLD completed measures of hoarding symptom severity (Savings Inventory-Revised: SI-R), executive functioning (WAIS-IV Digit Span, Letter-Number Sequencing, Coding; Stroop Interference; Trail Making Test-Part B; Letter Fluency), functional ability (World Health Organization Disability Assessment Schedule-II-Short), and depression severity (Hamilton Depression Rating Scale) at post-treatment. Pearson's Chi-squared tests evaluated group differences in cognitive and functional impairment rates and depression treatment response between participants with (HD+LLD) and without (LLD-only) clinically significant hoarding symptoms. Linear regressions were used to examine the association between hoarding symptom severity and executive function performance and functional ability and included as covariates participant age, years of education, gender, and concurrent depression severity.

At post-treatment, 24.1% (20/83) of participants with LLD met criteria for clinically significant hoarding symptoms (SI-R.41). Relative to LLD-only, the LLD+HD group demonstrated greater impairment rates in Letter-Number Sequencing (χ2(1)=4.0, p=.045) and Stroop Interference (χ2(1)=4.8, p=.028). Greater hoarding symptom severity was associated with poorer executive functioning performance on Digit Span (t(71)=-2.4, β=-0.07, p=.019), Letter-Number Sequencing (t(70)=-2.1, β=-0.05, p=.044), and Letter Fluency (t(71)=-2.8, β=-0.24, p=.006). Rates of functional impairment were significantly higher in the LLD+HD (88.0%) group compared to the LLD-only (62.3%) group, (χ2(1)=5.41, p=.020). Additionally, higher hoarding symptom severity was related to greater disability (t(72)=2.97, β=0.13, p=.004). Furthermore, depression treatment response rates were significantly lower in the LLD+HD group at 24.0% (6/25) compared to 48.3% (28/58) in the LLD-only group, χ2(1)=4.26, p=.039.

The present study is among the first to report prevalence of clinically significant hoarding symptoms in primary presenting LLD. The findings of 24.1% co-occurrence of HD in primary presenting LLD and increased burden on executive functioning, disability, and depression treatment outcomes have important implications for intervention and prevention efforts. Hoarding symptoms are likely under-evaluated, and thus may be overlooked, in clinical settings where LLD is identified as the primary diagnosis. Taken together with results indicating poorer depression treatment response in LLD+HD, these findings underscore the need for increased screening of hoarding behaviors in LLD and tailored interventions for this LLD+HD group. Future work examining the course of hoarding symptomatology in LLD (e.g., onset age of hoarding behaviors) may provide insights into the mechanisms associated with greater executive dysfunction and disability.