Renee J. Thompson

Walk on the bright side: physical activity and affect in major depressive disorder.

Although prescribed exercise has been found to improve affect and reduce levels of depression, we do not know how self-initiated everyday physical activity influences levels of positive affect (PA) and negative affect (NA) in depressed persons. Fifty-three individuals diagnosed with Major Depressive Disorder (MDD) and 53 never-depressed controls participated in a seven-day experience sampling study. Participants were prompted randomly eight times per day and answered questions about their physical activity and affective state. Over the week, the two groups of participants did not differ in average level of physical activity. As expected, participants with MDD reported lower average PA and higher average NA than did never-depressed controls. Both participants with MDD and controls reported higher levels of PA at prompts after physical activity than at prompts after inactive periods; moreover, for both groups of participants, PA increased from a prompt after an inactive period to a subsequent prompt at which activity was reported. Depressed participants in particular showed a dose-response effect of physical activity on affect: longer duration and/or higher intensity of physical activity increased their PA significantly more than did short duration and/or lower intensity physical activity. Physical activity did not influence NA in either group. In contrast to previous treatment studies that examined the effects of prescribed structured exercise, this investigation showed that self-initiated physical activity influences PA. These findings also underscore the importance of distinguishing between PA and NA to gain a more comprehensive understanding of the effects of physical activity on affect in MDD.

The Everyday Emotional Experience of Adults with Major Depressive Disorder: Examining Emotional Instability, Inertia, and Reactivity

Investigators have begun to examine the temporal dynamics of affect in individuals diagnosed with major depressive disorder (MDD), focusing on instability, inertia, and reactivity of emotion. How these dynamics differ between individuals with MDD and healthy controls have not before been examined in a single study. In this study, 53 adults with MDD and 53 healthy adults carried hand-held electronic devices for approximately 7 days and were prompted randomly 8 times per day to report their levels of current negative affect (NA), positive affect (PA), and the occurrence of significant events. In terms of NA, compared with healthy controls, depressed participants reported greater instability and greater reactivity to positive events, but comparable levels of inertia and reactivity to negative events. Neither average levels of NA nor NA reactivity to, frequency or intensity of, events accounted for the group difference in instability of NA. In terms of PA, the MDD and control groups did not differ significantly in their instability, inertia, or reactivity to positive or negative events. These findings highlight the importance of emotional instability in MDD, particularly with respect to NA, and contribute to a more nuanced understanding of the everyday emotional experiences of depressed individuals.

BDNF genotype moderates the relation between physical activity and depressive symptoms.

OBJECTIVE To test whether the BDNF gene interacts with exercise to predict depressive symptoms. Physical activity is associated with a range of positive health outcomes, including fewer depressive symptoms. One plausible mechanism underlying these findings involves Brain-Derived Neurotrophic Factor (BDNF), a protein hypothesized to limit or repair the damage caused by stress. Physical activity increases expression of BDNF, which may enhance brain health. BDNF expression is controlled by the BDNF gene. Compared with individuals without a BDNF met allele, met-allele carriers have a lower expression of BDNF, which has been associated with Major Depressive Disorder. DESIGN Eighty-two healthy adolescent girls were genotyped for the BDNF val66met polymorphism, and their depressive symptoms and physical activity were assessed using questionnaires. MAIN OUTCOME MEASURES BDNF genotype, Childrens Depression Inventory, and the Physical Activity Questionnaire for Older Children and Adolescents. RESULTS The BDNF polymorphism was found to moderate the relation between exercise and depressive symptoms: being physically active was protective for girls with a BDNF met allele (fewer depressive symptoms) but not for girls with the val/val polymorphism. CONCLUSION By integrating psychological and biological factors, the present study enhances our understanding of how physical activity contributes to resilience to psychopathology.

Why is Past Depression the Best Predictor of Future Depression? Stress Generation as a Mechanism of Depression Continuity in Girls

This study examined whether a transactional interpersonal life stress model helps to explain the continuity in depression over time in girls. Youth (86 girls, 81 boys; M age = 12.41, SD = 1.19) and their caregivers participated in a three-wave longitudinal study. Depression and episodic life stress were assessed with semistructured interviews. Path analysis provided support for a transactional interpersonal life stress model in girls but not in boys, wherein depression predicted the generation of interpersonal stress, which predicted subsequent depression. Moreover, self-generated interpersonal stress partially accounted for the continuity of depression over time. Although depression predicted noninterpersonal stress generation in girls (but not in boys), noninterpersonal stress did not predict subsequent depression.

Flexible Emotional Responsiveness in Trait Resilience

Field studies and laboratory experiments have documented that a key component of resilience is emotional flexibility--the ability to respond flexibly to changing emotional circumstances. In the present study we tested the hypotheses that resilient people exhibit emotional flexibility: (a) in response to frequently changing emotional stimuli and (b) across multiple modalities of emotional responding. As participants viewed a series of emotional pictures, we assessed their self-reported affect, facial muscle activity, and startle reflexes. Higher trait resilience predicted more divergent affective and facial responses (corrugator and zygomatic) to positive versus negative pictures. Thus, compared with their low-resilient counterparts, resilient people appear to be able to more flexibly match their emotional responses to the frequently changing emotional stimuli. Moreover, whereas high-trait-resilient participants exhibited divergent startle responses to positive versus negative pictures regardless of the valence of the preceding trial, low-trait-resilient participants did not exhibit divergent startle responses when the preceding picture was negative. High-trait-resilient individuals, therefore, appear to be better able than are their low-resilient counterparts to either switch or maintain their emotional responses depending on whether the emotional context changes. The present findings broaden our understanding of the mechanisms underlying resilience by demonstrating that resilient people are able to flexibly change their affective and physiological responses to match the demands of frequently changing environmental circumstances.

5‐HTTLPR moderates the effect of relational peer victimization on depressive symptoms in adolescent girls

BACKGROUND Relational peer victimization is associated with internalizing symptoms. Compared to boys, girls are more likely to be both relationally victimized by peers and distressed by the victimization. While previous studies have reported that a functional polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) moderates the effect of stressful life events on depressive symptoms, the present study is the first to evaluate the interaction of this polymorphism with relational peer victimization to predict level of depressive symptoms in young girls. METHODS Participants were 78 girls ages 10 to 14 who had no current or past Axis I disorder. Girls were genotyped for 5-HTTLPR; peer victimization was assessed with the Social Experiences Questionnaire, and depressive symptoms with the Childrens Depression Inventory. RESULTS The 5-HTTLPR polymorphism alone did not predict level of depressive symptoms; the interaction of 5-HTTLPR and relational peer victimization, however, was a significant predictor of depressive symptoms. Follow-up analyses indicated that peer victimization significantly predicted level of depressive symptoms only for girls who were homozygous for the short allele, and not for girls homozygous for the long allele or who were heterozygous for the short and long alleles. CONCLUSIONS The findings support the diathesis-stress model of depression: having two 5-HTTLPR short alleles confers vulnerability to depressive symptoms in adolescent girls when they experience relational peer victimization. These findings also suggest that relational peer victimization, at least for girls with genetic vulnerability, is a significant source of stress and should be recognized in the monitoring and prevention of bullying.

Emotional correlates of the different dimensions of schizotypal personality disorder.

Two studies explored which different dimensions of schizotypal personality disorder (SPD) were associated with negative affect, attention to emotions, clarity of emotions, and emotional intensity/instability. Study 1 included 247 college students, and questionnaires were used to measure SPD. Study 2 included 225 community residents, oversampling for individuals with elevated levels of SPD, and semistructured diagnostic interviews were used to measure SPD. In both studies (a) higher levels of negative affect were associated with higher levels of both cognitive-perceptual and interpersonal symptoms, (b) cognitive-perceptual disturbances were associated with greater attention to emotion, whereas interpersonal disturbances were associated with less attention to emotion, and (c) lower levels of emotional clarity were associated with higher levels of suspiciousness.

Cross-sectional and longitudinal relations between affective instability and depression

BACKGROUND There is a growing recognition that emotional traits are important for understanding many mental health disorders, including major depressive disorder (MDD). The present research examined (a) the relation between MDD and the emotional trait of affective instability, and (b) whether individual facets of affective instability, affect intensity and affect variability, exhibited unique relations with anhedonic depression. METHODS In Study 1, affective instability and MDD were both assessed via clinical interviews in an adult community sample (n=288). In Studies 2 and 3, the relations between anhedonic depression and affect variability and affect intensity were assessed cross-sectionally using self-report measures in a college student sample (n=142; Study 2) and a female community sample (n=101; Study 3). Study 3 also prospectively examined whether affect variability and/or intensity predicted changes in anhedonic depression over two months. RESULTS In Study 1, affective instability and MDD were significantly associated, even after excluding individuals experiencing a current major depressive episode. In Studies 2 and 3, affect variability but not affect intensity was significantly, positively associated with anhedonic depression. In Study 3, affect variability but not affect intensity prospectively predicted increases in anhedonic depression. LIMITATIONS Future studies should assess the entire Bipolar Disorder spectrum and utilize event sampling, permitting the examination of other facets of affective instability (e.g., temporal dependency) and address other limitations of retrospective measures (e.g., recall bias). CONCLUSIONS These findings suggest that affective instability and particularly affect variability are associated with MDD and anhedonic depression. The tendency to experience frequent fluctuations in mood may constitute an important risk factor for depression.

Emotion-Network Density in Major Depressive Disorder

Major depressive disorder (MDD) is a prevalent disorder involving disturbances in mood. There is still much to understand regarding precisely how emotions are disrupted in individuals with MDD. In this study, we used a network approach to examine the emotional disturbances underlying MDD. We hypothesized that compared with healthy control individuals, individuals diagnosed with MDD would be characterized by a denser emotion network, thereby indicating that their emotion system is more resistant to change. Indeed, results from a 7-day experience sampling study revealed that individuals with MDD had a denser overall emotion network than did healthy control individuals. Moreover, this difference was driven primarily by a denser negative, but not positive, network in MDD participants. These findings suggest that the disruption in emotions that characterizes depressed individuals stems from a negative emotion system that is resistant to change.

Feeling Blue or Turquoise? Emotional Differentiation in Major Depressive Disorder

Some individuals have very specific and differentiated emotional experiences, such as anger, shame, excitement, and happiness, whereas others have more general affective experiences of pleasure or discomfort that are not as highly differentiated. Considering that individuals with major depressive disorder (MDD) have cognitive deficits for negative information, we predicted that people with MDD would have less differentiated negative emotional experiences than would healthy people. To test this hypothesis, we assessed participants’ emotional experiences using a 7-day experience-sampling protocol. Depression was assessed using structured clinical interviews and the Beck Depression Inventory-II. As predicted, individuals with MDD had less differentiated emotional experiences than did healthy participants, but only for negative emotions. These differences were above and beyond the effects of emotional intensity and variability.