Cognitive reserve-mediated neural modulation of emotional control and regulation in people with late-life depression

Abstract

Late-life depression (LLD) is an affective disorder that is highly prevalent among older people. Cognitive reserve (CR) refers to an active process that facilitates the flexibility and efficiency of the neural networks to compensate for impairments that emerge in consequence of brain pathology. The current functional magnetic resonance imaging study investigated whether and how CR affects emotional regulation, level of depression severity and neural activity associated with affective control during emotional Stroop (eStroop) task. Altogether, 90 older people participated in this study, 50 of whom suffered from LLD. We used years of education and verbal fluency capacity as proxies for CR. Clinical participants with relatively higher CR presented with milder degrees of depression, better eStroop performance and stronger neural activity in the middle frontal gyrus (MFG) involved with exercising affective control. Results of the mediation analysis indicated that both education and verbal fluency significantly mediated the association between the depression severity and MEG activity. These results suggest a negative association between CR and age-related clinical symptoms of emotional dysregulation. Our neurobehavioral findings provide supportive evidence that CR implies efficiency of top-down emotional regulation and operates as a protective factor against emotional and cognitive vulnerability in the aging brain.

Emotion processing in depression and anxiety disorders in older adults: systematic review

“…No group×valence analysis was reported. Finally, in 55 people with LLD and 40 controls, using an eStroop, 50 controls were more accurate and had shorter latencies. There was no effect of emotion on accuracy, but there was on latency, with both positive and negative words associated with longer latencies.…”

“…Participants with depression ( n = 33) showed greater subgenual cingulate activity during affective processing compared with controls ( n = 27) with a significant correlation between white matter hyperintensity and activity. Huang et al 50 (55 participants with LLD, 40 controls) showed reduced activation in middle frontal gyrus and left dorsolateral prefrontal cortex, and increased activation in anterior cingulate cortex, in the LLD group compared with controls in a study examining activation during an eStroop task. This was mediated by cognitive reserve such that greater cognitive reserve correlated with greater middle frontal gyrus activation in the LLD group.…”

“…Furthermore, a similar effect was not seen in a separate examination of effects on an eStroop test. 49 Although Huang et al 50 did not find the hypothesised eStroop effect in LLD, there was more preserved middle frontal gyrus activity during eStroop performance in people with greater cognitive reserve. This suggests that cognitive reserve (measured using a combination of years of education and an executive task) mediates a more top-down emotional regulation, i.e.…”

“…White matter changes were associated with an exaggeration of the increase in subgenual cingulate activation seen during emotion processing in LLD. 59 In the study of Huang et al 50 , severity of depression was associated with reduced medial frontal activation during emotion processing, but this was attenuated by having greater cognitive reserve (measured using years of education and verbal fluency). Both findings suggest a situation in which if processing capacity is reduced for a variety of possible reasons, this may impair efficient emotion processing, resulting in processing being driven to a greater extent by limbic structures.…”

“…73 The studies in LLD are broadly in line with this pattern with the largest studies showing increased activation of limbic structures or decreased activation of prefrontal structures in LLD compared with controls, in line with a general pattern of reduced top-down processing. 50,54,59 Of interest, there was also evidence of an interaction between depression and both white matter lesions 59 and cognitive reserve 50 in determining patterns of activation during emotional processing. White matter changes were associated with an exaggeration of the increase in subgenual cingulate activation seen during emotion processing in LLD.…”