The Queen and I: neural correlates of altered self-related cognitions in major depressive episode

[Belief updating and mood congruence in depressive disorder]

Depressive disorder is characterized by a polymorphic symptomatology associating emotional, cognitive and behavioral disturbances. One of the most specific symptoms is negative beliefs, called congruent to mood. Despite the importance of these beliefs in the development, the maintenance, and the recurrence of depressive episodes, little is known about the processes underlying the generation of depressive beliefs. In this paper, we detail the link between belief updating mechanisms and the genesis of depressive beliefs. We show how depression alters information processing, generating cognitive immunization when processing positive information, affective updating bias related to the valence of belief and prediction error, and difficultie to disengage from negative information. We suggest that disruption of belief-updating mechanisms forms the basis of belief-mood congruence in depression.

Self-other referential neural processing in social anxiety disorder and major depressive disorder

BACKGROUND

Social anxiety disorder (SAD) and major depressive disorder (MDD) are highly comorbid and share impairments in self-referential and social processing. Many naturalistic judgements activate these processes concurrently, which can be referred to as "self-other referential processing". We sought to examine its neural correlates in young people with SAD and MDD using a novel experimental task.

METHODS

Fifty six young people aged 16 to 25 with diagnoses of SAD and/or MDD (15 with SAD [M = 20.3 years, 60% female], 17 with MDD [M = 19.8 years, 53% female], 24 with comorbid SAD and MDD [M = 19.8 years, 67% female]) and 76 age and gender-matched healthy controls (HCs; M = 20.7 years, 66% female) completed a novel self-other referential processing fMRI task that involved rating how much one related to emotional faces in active conditions and judging how far apart each person's eyes were in control conditions.

RESULTS

Participants with SAD had more and those with MDD had less activity in social cognitive areas than HCs when processing social information across all conditions and emotion types. Participants with comorbid SAD-MDD exhibited a distinct pattern of neural activity to patients with single diagnoses. Across the whole sample, the activation of reward system areas (the medial orbitofrontal cortex and caudate) in response to increasing relatedness correlated positively with a dimensional measure of social anxiety.

CONCLUSIONS

Young people with SAD, MDD and comorbid SAD-MDD showed deficits in social processing, but they were not specifically related to self-other referential processing. Dimensional social anxiety symptoms were correlated with reward system activation, suggesting that such symptoms are associated with an overestimation of the hedonic value of social stimuli. These novel findings have implications for our understanding of the neural correlates of SAD and MDD, suggesting that alterations in social processing and reward functioning underlie the impairments in self and social processing that characterize both disorders.

"Average is good, extremes are bad" - Non-linear inverted U-shaped relationship between neural mechanisms and functionality of mental features

Traditionally, studies emphasize differences in neural measures between pathological and healthy groups, assuming a binary distinction between the groups, and a linear relationship between neural measures and symptoms. Here, we present four examples that show a continuous relation across the divide of normal and pathological states between neural measures and mental functions. This relation can be characterized by a non-linear inverted-U shaped curve. Along this curve, mid-range or average expression of a neural measure is associated with optimal function of a mental feature (in healthy states), whereas extreme expression, either high or low, is associated with sub-optimal function, and occurs in different neural disorders. Neural expression between the optimal or intermediate and pathological or extreme values is associated with sub-optimal function and at-risk mental states. Thus, this model of neuro-mental relationship can be summarized as "average is good, extremes are bad". By focussing on neuro-mental relationships, this model can facilitate the transition of psychiatry from a categorical to a dimensional and individualized approach needed in the era of precision medicine.

Medial prefrontal disengagement during self-focus in formerly depressed patients prone to rumination

BACKGROUND

Medial prefrontal cortex (MPFC) activity during self-referential processing has been associated with rumination and found aberrant in depression. We investigated whether this aberrant activity reflects a trait marker that persists in remitted patients.

METHODS

Twenty-five patients fully remitted from major depression for at least 6 months, and 29 matched healthy controls were scanned with fMRI while presented with personality trait words in two conditions: Self condition asked whether the trait described themselves; General condition asked whether the trait was generally desirable. Contrasts-of-interest were examined in a factorial model and rumination correlates were examined in 2-sample t-tests with Ruminative Response Style score as covariate. All findings were reported at a conservative p < 0.05, with whole-brain peak-level family-wise error correction.

RESULTS

Self-referential processing increased anterior cortical midline activity to a similar extent in both groups. Dorsal anterior cingulate cortex (MNI(x,y,z) = -12,20,26) and dorsal MPFC (MNI(x,y,z) = -6,46,40) activity during self-referential processing was positively associated with rumination in healthy control subjects and negatively associated with rumination in remitted patients.

LIMITATIONS

A longitudinal design tracking the relationship between rumination and MPFC activity would have aided the interpretation of our findings as to whether high ruminators are exhibiting an adaptive process to maintain remission or whether it represents a maladaptive process considering that high ruminators have an increased vulnerability for relapse.

CONCLUSIONS

The association between increased anterior cortical midline activity during self-referential processing and rumination differentiated healthy controls from formerly depressed patients. Self-referential neural processing during remission from depression may depend on the cognitive tendencies to ruminate.