Asako Mori

Behavioral activation can normalize neural hypoactivation in subthreshold depression during a monetary incentive delay task.

BACKGROUND Late adolescents are under increased risk of developing depressive symptoms. Behavioral activation is an effective treatment for subthreshold depression, which can prevent the development of subthreshold depression into a major depressive disorder. However, the neural mechanisms underlying the efficacy of behavioral activation have not been clearly understood. We investigated neural responses during reward processing by individuals with subthreshold depression to clarify the neural mechanisms of behavioral activation. METHODS Late adolescent university students with subthreshold depression (n=15, age 18-19 years) as indicated by a high score on the Becks Depression Inventory-ll (BDI-ll) and 15 age-matched controls with a low BDI-ll score participated in functional magnetic resonance imaging scanning conducted during a monetary incentive delay task on two occasions. The Individuals in the subthreshold depression group received five, weekly behavioral activation sessions between the two scanning sessions. Moreover, they did not receive any medication until the study was completed. RESULTS Behavioral activation significantly reduced depressive symptoms. Moreover, compared to the changes in brain functions in the control group, the behavioral activation group showed functional changes during loss anticipation in brain structures that mediates cognitive and emotional regulation, including the left ventrolateral prefrontal cortex and angular gyrus. LIMITATIONS Replication of the study with a larger sample size is required to increase the generalizability of these results. CONCLUSIONS Behavioral activation results in improved functioning of the fronto-parietal region during loss anticipation. These results increase our understanding of the mechanisms underlying specific psychotherapies.

Effects of behavioural activation on the neural basis of other perspective self-referential processing in subthreshold depression: a functional magnetic resonance imaging study

Background It has been demonstrated that negatively distorted self-referential processing, in which individuals evaluate ones own self, is a pathogenic mechanism in subthreshold depression that has a considerable impact on the quality of life and carries an elevated risk of developing major depression. Behavioural activation (BA) is an effective intervention for depression, including subthreshold depression. However, brain mechanisms underlying BA are not fully understood. We sought to examine the effect of BA on neural activation during other perspective self-referential processing in subthreshold depression. Method A total of 56 subjects underwent functional magnetic resonance imaging scans during a self-referential task with two viewpoints (self/other) and two emotional valences (positive/negative) on two occasions. Between scans, while the intervention group (n = 27) received BA therapy, the control group (n = 29) did not. Results The intervention group showed improvement in depressive symptoms, increased activation in the dorsal medial prefrontal cortex (dmPFC), and increased reaction times during other perspective self-referential processing for positive words after the intervention. Also, there was a positive correlation between increased activation in the dmPFC and improvement of depressive symptoms. Additionally, there was a positive correlation between improvement of depressive symptoms and increased reaction times. Conclusions BA increased dmPFC activation during other perspective self-referential processing with improvement of depressive symptoms and increased reaction times which were associated with improvement of self-monitoring function. Our results suggest that BA improved depressive symptoms and objective monitoring function for subthreshold depression.

Behavioral characteristics of subthreshold depression.

BACKGROUND This study examines differences in behavioral characteristics among individuals who are not depressed and individuals with subthreshold depression, and depression. METHODS We conducted structured interviews with 111 undergraduate students, who also completed self-report scales. The participants were divided into a non-depression group, a subthreshold depression group, and a depression group based on results of the structured interview and the BDI-II. RESULTS There were significant differences in avoidance between depression group and other two groups. Also, for the environmental rewards, there were significant difference between the non-depressed group and the other two groups. LIMITATIONS The sample of depressed participants was small. The overall sample consisted only undergraduate students. CONCLUSIONS This study reported that there are different behavioral characteristics among non-depression, subthreshold depression, and depression groups. Whereas depression group is characterized by high frequency of avoidance and low environmental rewards, subthreshold depression group is characterized by only low environmental rewards.

Mechanisms of behavioral activation for late adolescents: Positive reinforcement mediate the relationship between activation and depressive symptoms from pre-treatment to post-treatment

BACKGROUND It is suggested that there is some support for notion that frequency of activity can lead to improved mood in behavioral activation, but this research is relatively imprecise. We investigated whether positive reinforcement mediates the relationship between activation and alleviation of depressive symptoms METHODS Late adolescents with sub-threshold depressive symptoms participated in the study. We conducted an intervention using behavioral activation with the participants. Then, pre-and post-treatment results of behavioral activation were compared. We used mediation analysis using the bootstrapping method to examine whether changes in reinforcement mediated the relationship between changes in activation and improvements in depressive symptoms. RESULTS Participants improved significantly at the post-intervention assessment, compared to the baseline assessment. Results of mediation analysis indicated that reinforcement significantly mediated the relationship between activation and depressive symptoms, whereas activation alone had no a direct effect on depressive symptoms. LIMITATIONS Further studies with more diverse samples of participants are required in order to generalize the results of this study to more diverse populations. CONCLUSIONS The study provides the first full mediational test of behavioral activation model including both measures of activation and positive reinforcement, and we found support for behavioral activations presumed mechanism of action that contact with positive reinforcement mediates the relation between activity and depression.

The neural correlates of the metacognitive function of other perspective: a multiple regression analysis study

Perspective taking is defined as the social cognitive function of imagining the world or imagining oneself from another’s viewpoint. Previously, we reported that behavioral activation increased the dorsal medial prefrontal cortex (dmPFC) activation during other perspective self-referential processing for positive words in subthreshold depression, but did not report whether metacognitive function was related to the dmPFC activation. Therefore, we sought to test the relationship between the dmPFC activation during other perspective self-referential processing for positive words and an individual’s metacognitive evaluation of other perspective. Thirty-four healthy individuals underwent functional MRI scans during a referential task with two viewpoints (self/other) and two emotional valences (positive/negative). Neural activation during other perspective self-referential processing for positive words was correlated with the metacognitive function of participants measured by the Interpersonal Reactivity Index (IRI). We found a positive correlation between the score in perspective taking of the IRI and activation in the dmPFC during other perspective self-referential processing for positive words. The present findings showed that self-report questionnaires assessing participants’ metacognitive evaluation of other perspective were correlated with dmPFC activation during positive metacognition of other perspective task. However, we did not conduct a behavioral activation intervention in the present study. The present students were healthy. The IRI is a subjective measure of multidimensional trait empathy. It is necessary to develop an objective measurement for the metacognitive function of other perspective in the near future.

Effects of behavioral activation on default mode network connectivity in subthreshold depression: A preliminary resting-state fMRI study

BACKGROUND Subthreshold depression is a risk factor for major depressive disorder, and it is known to have a negative impact on quality of life (QOL). Although behavioral activation, which is one type of cognitive behavioral therapy, is an effective psychological intervention for subthreshold depression, neural mechanisms of behavioral activation are unclear. Enhanced functional connectivity between default mode network (DMN) and the other regions has been demonstrated in participants with subthreshold depression. The purpose of this study was to examine the effects of behavioral activation on DMN abnormalities by using resting-state functional MRI (rs-fMRI). METHODS Participants with subthreshold depression (N =40) were randomly assigned to either an intervention group or a non-intervention group. They were scanned using rs-fMRI before and after the intervention. Independent component analysis indicated three subnetworks of the DMN. RESULTS Analyzing intervention effects on functional connectivity of each subnetwork indicated that connectivity of the anterior DMN subnetwork with the dorsal anterior cingulate was reduced after the intervention. Moreover, this reduction was correlated with an increase in health-related QOL. LIMITATIONS We did not compare the findings with healthy participants. Further research should be conducted by including healthy controls to verify the results of this study. CONCLUSIONS Mechanisms of behavioral activation might be related to enhanced ability to independently use the dACC and the DMN, which increases an attention control to positive external stimuli. This is the first study to investigate neural mechanisms of behavioral activation using rs-fMRI.

Effects of behavioural activation on the neural circuit related to intrinsic motivation

Background Behavioural activation is an efficient treatment for depression and can improve intrinsic motivation. Previous studies have revealed that the frontostriatal circuit is involved in intrinsic motivation; however, there are no data on how behavioural activation affects the frontostriatal circuit. Aims We aimed to investigate behavioural activation-related changes in the frontostriatal circuit. Method Fifty-nine individuals with subthreshold depression were randomly assigned to either the intervention or non-intervention group. The intervention group received five weekly behavioural activation sessions. The participants underwent functional magnetic resonance imaging scanning on two separate occasions while performing a stopwatch task based on intrinsic motivation. We investigated changes in neural activity and functional connectivity after behavioural activation. Results After behavioural activation, the intervention group had increased activation and connectivity in the frontostriatal region compared with the non-intervention group. The increased activation in the right middle frontal gyrus was correlated with an improvement of subjective sensitivity to environmental rewards. Conclusions Behavioural activation-related changes to the frontostriatal circuit advance our understanding of psychotherapy-induced improvements in the neural basis of intrinsic motivation. Declaration of interest None.