Executive Functions and Subjective Cognitive Decline: The Moderating Role of Depressive Symptoms

Background: Executive dysfunction may be an early marker of neurodegenerative disorders, even if it is difficult to detect objectively. Subjective cognitive decline (SCD) may reflect subtle deficits in executive functions (EFs); however, SCD is also strongly influenced by affective factors such as depression. Whether depressive symptoms alter the link between EFs and SCD remains unclear. The present study tested whether depressive symptoms moderate the association between executive functioning and SCD. Methods: In this cross-sectional study, 65 outpatients completed a comprehensive assessment including executive functions (FAB), self-reported cognitive difficulties (CFI self-report), and depressive symptoms (PHQ-9). Descriptive statistics were performed, as well as a moderation analysis using PHQ-9 as moderator of the relationship between FAB and CFI self-report. Results: Participants (age: 69.28 ± 9.03) showed preserved EFs (FAB = 15.42, SD = 2.11), mild depressive symptoms (PHQ-9 = 6.57, SD = 5.02), and modest subjective difficulties (CFI = 4.87, SD = 2.57). The FAB main effect was positive but non-significant (β = 0.155, p = 0.266), while PHQ-9 was a significant positive predictor (β = 0.470, p ≤ 0.001). The interaction effect was significant (95% CI: [-0.166, -0.015], β = -0.343, p = 0.020). Specifically, simple slope analysis showed that at low levels of depression (-1 SD), better executive functioning was associated with higher SCD (β = 0.498, p = 0.039). Instead, the association was negative but non-significant at moderate (β = 0.155, p = 0.266) and high levels of depression (+1 SD) (β = -0.188, p = 0.229). Conclusions: In SCD, depressive symptoms are a stronger correlate of subjective cognitive difficulties than executive functions. Moreover, higher depression may modulate the executive functions-complaint link, reducing and potentially reversing it as symptom burden increases. Screening and treatment of depressive symptoms should be integrated into SCD assessment and care. Longitudinal and multicenter studies are needed to more deeply understand these preliminary results.