From a 2017 WHO report, it was concluded that depression impacted 322 million people worldwide. For every one that underwent treatment for depression, 45-65% never reached remission. Even those who did reach remission had about a 50% chance of relapsing after 1-2 years. Mainstream interventions for treating depression have focused on repairing associated negative emotions, but do little in increasing positive emotions. Thus, interventions that target impairments in positive emotions could be critical in diminishing depression. Depression is related to impaired emotion reactivity and regulation, with emotion reactivity being an initial baseline response and emotion regulation being the process that influences an initial emotional response. However, there’s been difficulty disentangling emotion reactivity and regulation, and doing so is important in understanding how current treatments for depression should be refined. In the talk “Individual differences and neural correlates of emotion reactivity and regulation: potential intervention targets in depression” presented by Kahrilas (2021), the researcher presented three studies conducted to disentangle emotion reactivity and regulation to bring us closer to conceiving neuroscience-informed treatments for depression.
The first study was in regards to the concept of savoring the moment and linking affectivity and depression. Savoring capacity is the capacity for an individual to attend to, appreciate, and enhance the positive experience of one’s life. As such, one’s savoring capacity is the index of one’s ability to regulate their positive emotions. When you are savoring, you may anticipate future events before they occur (anticipating), or you can attend to and appreciate positive events as they are occurring in the present moment (savoring the moment), or you can reminisce upon positive events after they have occurred (reminiscing). Regardless of the temporal focus, each of these temporal domains of savoring is indicative of one’s ability to savor emotions in the present moment. In this study, 1,618 participants were measured with the Savoring Beliefs Inventory (SBI), the Mood and Anxiety Symptom Questionnaire (MASQ), the Patient Health Questionnaire (PHQ-9), and the Penn State Worry Questionnaire (PSWQ). Results showed a positive relationship between positive affectivity and each of the three temporal domains of savoring, and a negative relationship between positive affectivity and depression. A negative relationship between negative affectivity and each of the three temporal domains of savoring was also found, and a positive relationship between negative affectivity and depression was observed. Moreover, savoring the moment was the sole predictor of depression, suggesting that momentary savoring has a higher specificity to depression and might be a more effective intervention target.
In the second study, the neural chronometry of positive and negative emotion reactivity and regulation was investigated. The main goal of this study was to disentangle the constructs of emotion reactivity and emotion regulation. Since the time course of reactivity and regulation likely overlap, electroencephalography (EEG) is an efficient psychophysiological measure of electrical cortical activity by event-related potentials (ERPs) with millisecond (ms) temporal resolution that can be used to evaluate the chronometry of reactivity and regulation processes. The present study utilized EEG methods to determine the neural time course of emotion reactivity and regulation to provide knowledge as to how these processes are implicated and how they can be altered in depression. A principal component approach (PCA) was used to measure ERPs, which is a dimension reduction technique that takes a large number of variables and reduces them to a smaller set of variables that constitute linear combinations of the original data set. The most common waveform from PCA is the Late Positive Potential (LPP), which is a positive slow wave EEG component observed as early as 300 ms following stimulus onset. LPP is an established index of evaluative congruency, valence, and arousal in response to visual stimuli, and is selectively enhanced in response to positive and negative visual stimuli relative to neutral stimuli. The study also examined early visual processes, seen with the N170 (a negative peak occurring at 170 ms) and EPN (negative peak occurring around 200-300 ms), since these components have been studied in previous literature on facial processing, showing that these components are enhanced in response to images of negative and positive faces. The present study used 120 standardized images from the open-affective standardized image set, which are images normed on valence (unpleasant and pleasant) and arousal (not aroused and aroused). Using the image sets, there were three distinct categories: 40 positive, 40 negative, 40 neutral. For the positive and negative image sets, there were three sets of instructions for participants: increase or decrease the emotional intensity they felt in response to the images, or passively view the images. For neutral images, participants were told to just passively view them. After viewing the images, participants rated how positive or negative they felt in the present moment on a 1-7 Likert Scale. They also reported the arousal of the emotion and the difficulty of the task. The chronometry of reactivity unfolded from 162 ms to 740 ms, with stable arousal and valence effect throughout the time course. In terms of regulation, negative regulatory processes unfolded earlier at 124 ms to 259 ms, whereas positive regulatory processes occurred later from 259 ms to 740 ms. These findings are important because different types of psychopathology might manifest as dysregulating positive or negative emotion regulation or reactivity, suggesting that we might need different intervention processes depending on the symptomatology.
The third study presented summarized early neural activity as an indicator of the brightening effect. There are three theories of emotion reactivity in depression: positive attenuation (reduced reactivity in response to positive stimuli), negative potentiation (enhanced reactivity in response to negative stimuli), and emotion context insensitivity (ECI; reduced reactivity in response to positive and negative stimuli). Within the realm of lab-based research, ECI has emerged to be the most common finding; however, this is not the case in a different type of research called ecological momentary assessment. With this assessment, researchers have participants download an app on their phones and have them complete questionnaires throughout the day. A different pattern of emotion reactivity and depression emerges with this research, such that there is enhanced reactivity in response to positive stimuli in those with depression as opposed to those without depression. Much research of depression and emotion reactivity in psychopathology looks at depression as a heterogeneous cluster of symptoms, and findings from study 1 here show that positive affectivity shows specificity to depression, so Kahrilas was interested in how neural activity changes as a function of positive affectivity specifically, rather than depression as a whole. Previous research showed that those with depression tend to exhibit smaller amplitudes in response to both positive and negative images, which is consistent with the ECI view, where we see less reactivity in response to visual stimuli regardless of if they are positive or negative. Previous studies also show that those endorsing lower levels of positive affectivity tend to exhibit attenuated reactivity in response to negative and positive images. Moreover, previous literature employing structural equation modeling found a model corresponding to ECI that found associations between viewing pleasant and unpleasant images and depressive symptoms that were approaching significance. Following these findings, the present study hypothesized that reactivity in response to positive and negative stimuli would be positively associated with positive affectivity, such that those with depression (those with lower positive affectivity) would report smaller amplitudes in response to those images, and that an ECI model would best map onto the findings. Study 3 used the same EEG paradigm as Study 2. Study 3 also used the same sample as study 2, but included a new sample of participants from a different study in conjunction with the current impact lab that was recruited based on depressive symptoms. More specifically, participants recruited were those that endorsed moderate levels of depression, and Kahrilas harmonized them with the previous sample that was not recruited on this basis of depression. This introduces more variance of measures of central tendency, which results in a greater dimensional perspective of the concept of interest. A positive component peak at 371 ms at bilateral occipital electrode sites was found. Negative and positive images elicited augmented amplitude relative to neutral images. Another positive component occurring later in the time course was found, peaking at about 736 ms at a cluster of bilateral centroparietal electrode sites. A negative component peaking at 257 ms was also observed. For PCA in study 3, there was no peak at 162 ms that was observed in study 2, suggesting that there might be alterations in the early visual components with the introduction of depressive symptoms. For the 257 ms component results, the association between the residual variance of the positive viewing condition and positive affectivity was strongly correlated. However, there was no association found between negative viewing conditions and positive affectivity. Since the EPN is a negative-going component, this means that the positive association is in the opposite direction than the ECI model hypothesized. This is explained by the brightening effect model, which was found in the ecological momentary assessment literature, that says there's augmented emotional reactivity in response to positive images as a function of depression. The brightening effect model was the best model for the 257 ms component, which draws the association between positive images and positive affectivity, meaning that early visual ERP components might show specificity to those with low positive affectivity. For the 371 ms and 736 ms component results, nothing outperformed the measurement model here, meaning that these later ERP components may be independent of internalizing symptoms. Conclusions from study 3 were that only the positive viewing condition for the early visual 257 ms component was negatively related to positive affectivity, consistent with the brightening effect. Furthermore, later ERP components were not related to internalizing symptoms. Therefore, interventions that target early neural processes may strengthen positive affectivity and alleviate depression.
Overall, Kahrilas’ Study 1 found that momentary savoring might diminish depressive symptoms for those with low positive affectivity and high negative affectivity. Study 2 disentangled positive emotion reactivity and regulation. Neural reactivity unfolded from 162 ms to 740 ms with stable arousal and valence effects. Negative regulatory processes unfolded at 124 ms to 259 ms, and positive regulatory processes occurred later from 259 ms to 740 ms. Study 3 found that early neural activity is related to positive affectivity. These studies collectively bring us closer to conceiving neurobiological treatments for depression.
Similar to Kahrilas’ Study 2 that investigated the neural chronometry of positive and negative emotion reactivity and regulation to disentangle the constructs of emotion reactivity and emotion regulation, Ebneabbasi et al.’s (2021) “Emotion processing and regulation in major depressive disorder: A 7T resting-state fMRI study” went off the concept that debilitated emotion processing (EP) and emotion regulation (ER) are key factors in the pathophysiology of major depressive disorder (MDD), with biased processing and impaired regulation of affective stimuli. EP and emotion reactivity are equal. Disturbances of EP are seen with excessive attention toward negative events, and disturbances of ER correspond to insufficient suppression of negative affect and incompetent savoring of positive ones. Like Kahrilas’ previous issue with disentangling EP and ER, the present study utilized regional amplitude of low frequency fluctuations (ALFF) and whole-brain functional connectivity (FC) of EP- and ER-related areas compared between 32 healthy controls (HC) and 20 MDD patients to discern if EP- and ER-related areas are linked to regulatory behavior and whether this relation is impaired in MDD. Previous literature found that higher amygdala reactivity led to greater prefrontal activity, thus resulting in greater regulatory behavior. In MDD, previous analyses found hyperactivity of the amygdala and hypoactivity of the lateral prefrontal cortex with exposure to negative stimuli, suggesting an augmented emotional reactivity and decreased downregulation of debilitated amygdala reactivity, offsetting prefrontal recruitment, and meta-analytic disparities in MDD. Moreover, it was examined whether EP-related areas are predictors of ER-related areas and regulatory behavior in both experimental groups, and the brain-behavior associations between EP- and ER-related brain areas and depression severity were assessed. Results showed that affective areas were regionally and/or connectively impaired in MDD patients, and EP- and ER-related areas are disturbed in MDD patients. Overloading emotional reactivity in the amygdala has the potential to inversely affect cognitive control processes in prefrontal cortices, resulting in decreased regulatory actions. The amygdala plays a role in encoding relevant stimuli, provoking affective emotional responses. Higher amygdala activation was also found with exposure to negative stimuli in MDD patients, with prolonged processing of negative information, confirming Kahrilas’ finding that negative affectivity is positively associated with depression. Following the Kahrilas study that momentary savoring may diminish depressive symptoms, the current study found a decreased FC between the ventrolateral prefrontal cortex and intraparietal sulcus in MDD patients, suggesting an inability of MDD patients to rely on savoring capacity and attend to positive emotions in the present. Altogether, these findings provide new insights on the underlying neural correlates of affective dysfunctions experienced with depression, which was a future goal of the Kahrilas study.
References
Ebneabbasi, A., Mahdipour, M., Nejati, V., Li, M., Liebe, T., Colic, L., Leutritz, A. L., Vogel, M., Zarei, M., Walter, M., & Tahmasian, M. (2021). Emotion processing and regulation in major depressive disorder: A 7T resting-state fMRI study. Human brain mapping, 42(3), 797-810.
Foti, D., Hajcak, G., & Dien, J. (2009). Differentiating neural responses to emotional pictures: evidence from temporal-spatial PCA. Psychophysiology, 46(3), 521-530.
Hill, K. E., South, S. C., Egan, R. P., & Foti, D. (2019). Abnormal emotional reactivity in depression: Contrasting theoretical models using neurophysiological data. Biological psychology, 141, 35-43.
Silton, R. L., Kahrilas, I. K., Skymba, H. V., Smith, J., Bryant, F. B., & Heller, W. (2020). Regulating positive emotions: Implications for promoting well-being in individuals with depression. Emotion, 20(1), 93-97.
