Stress and Reward Function in Concurrent Depression and Chronic Cannabis Use

The co-occurrence of major depressive disorder (MDD) and cannabis use is a common clinical presentation. Chronic cannabis use is associated with poor depression symptom course and functional outcomes in MDD. The endocannabinoid system through which cannabis acts is implicated in the regulation of stress responses and reward processing underlying anhedonia, which may be putative processes through which depression outcomes are worsened with chronic cannabis use. This investigation utilized a prospective design to examine differences in depression, functioning, perceived stress, and facets underlying anhedonia (consummatory and anticipatory pleasure, motivation, and reward sensitivity/responsiveness) between the following groups: individuals with MDD and chronic cannabis (DEP x CAN) versus MDD alone (DEP). Aims in this investigation included: to examine whether chronic cannabis in those with MDD is associated with (i) greater levels of anhedonia, (ii) greater levels of depression severity and poorer ability to function at work and socially, (iii) stronger relations between anhedonia and poor depression outcomes, and (iv) greater levels of perceived stress, as well as stronger relations between stress and poor depression outcomes. Assessments were completed biweekly for two months. Results did not support group differences in self-reported anhedonia, perceived stress, or associations between stress and depression severity and functioning over the study period. Group differences in depression severity and in the associations between facets underlying anhedonia and outcomes were demonstrated. Higher consummatory pleasure was associated with future lower depression in the DEP group, whereas higher consummatory pleasure and higher reward sensitivity/responsiveness was associated with worse functioning at a later week in the DEP x CAN group. Theoretically, while deficits in appetitive behaviour and sensitivity to stress are both posited to be central to the maintenance of depression as well as later stages of substance misuse, results do not support an additive effect of cannabis use on these two processes beyond that which is a function of major depression. While results highlight the importance of attending to the various facets of reward processing dysfunction underlying anhedonia, replication in larger samples with greater power, as well as incorporation of behavioural measures alongside self-report will be important to strengthen present findings.

Department dc:contributor.department

Psychological Clinical Science

Year dc:date.issued

2023

Author dc:creator

• Thiruchselvam, Thulasi

Advisors dc:contributor.advisor

• Quilty, Lena C
• Bagby, R. Michael

Handle dc:identifier.uri

http://hdl.handle.net/1807/130048

OAI identifier oai:identifier

oai:utoronto.scholaris.ca:1807/130048