Pain and major depressive disorder: Associations with cognitive impairment as measured by the THINC-integrated tool (THINC-it)

Objectives: To examine the role of pain on cognitive function in adults with major depressive disorder (MDD).

Methods: Adults (18-65) with a Diagnostic and Statistical Manual - Fifth Edition (DSM-5)-defined diagnosis of MDD experiencing a current major depressive episode (MDE) were enrolled (n_MDD=100). All subjects with MDD were matched in age, sex, and years of education to healthy controls (HC) (n_HC=100) for comparison. Cognitive function was assessed using the recently validated THINC-integrated tool (THINC-it), which comprises variants of the choice reaction time (i.e., THINC-it: Spotter), One-Back (i.e., THINC-it: Symbol Check), Digit Symbol Substitution Test (i.e., THINC-it: Codebreaker), Trail Making Test - Part B (i.e., THINC-it: Trails), as well as the Perceived Deficits Questionnaire for Depression - 5-item (i.e., THINC-it: PDQ-5-D). A global index of objective cognitive function was computed using objective measures from the THINC-it, while self-rated cognitive deficits were measured using the PDQ-5-D. Pain was measured using a Visual Analogue Scale (VAS). Regression analyses evaluated the role of pain in predicting objective and subjective cognitive function.

Results: A significant between-group differences on the VAS was observed (p<0.001), with individuals with MDD reporting higher pain severity as evidenced by higher scores on the VAS than HC. Significant interaction effects were observed between self -rated cognitive deficits and pain ratings (p<0.001) on objective cognitive performance (after adjusting for MADRS total score), suggesting that pain moderates the association between self-rated and objective cognitive function.

Conclusions: Results indicated that pain is associated with increased self-rated and objective cognitive deficits in adults with MDD.

Implications: The study herein provides preliminary evidence demonstrating that adults with MDD reporting pain symptomatology and poorer subjective cognitive function is predictive of poorer objective cognitive performance. THINC-it is capable of detecting cognitive dysfunction amongst adults with MDD and pain.