The greatest percent reduction in anhedonia over the course of 8 weeks of treatment with antidepressant medication occurred among those depressed individuals showing the lowest RVLPFC activity during the positive suppress condition relative to the positive maintain condition during a positive emotion regulation task (, ). This finding suggests that lower RVLPFC activity during the positive suppress condition is more “normal,” and less RVLPFC dysfunction at T1 is associated with reduction in anhedonia by T2. Those who exhibit more RVLPFC activity during the “positive suppress” condition may be recruiting more cortical resources as a means to successfully suppress positive affect.
In general, the attempt to suppress positive affect may recruit RVLPFC because the task requires a certain level of cognitive control. For example, in healthy controls, the ability to suppress positive emotion likely requires an ability to halt the pre-potent tendency to fully experience or even relish in positive emotion in response to everyday positive stimuli, and RVLPFC and related cognitive control circuitry may be recruited to carry out this task “successfully.” In contrast, the symptom of anhedonia may result when an overactive cognitive control system acts relatively consistently and automatically, disrupting the person’s ability to freely experience positive affect in response to changing positive stimuli.
Lesser RVLPFC activity while trying to suppress positive emotion is conceptually similar to lesser RVLPFC activity observed in many other studies during a no-go trial of a go/no-go task. In the present context, those depressed individuals who exhibited lesser RVLPFC activity may have made more “errors.” In other words, they experienced more “breakthrough” positive affect—or positive affect generated in spite of the instruction not to—which is positive prognostically. For example, in response to a picture of an ice cream cone, those depressed individuals who can maintain a positive perspective on the image despite the verbal instruction to suppress their positive emotion, show a greater reduction in anhedonia over time. This can be thought of as “positive affect resiliency.” Importantly our data also showed that controls exhibited a similar trend ().
When combined with previous results indicating that depressed individuals inappropriately engage lateral PFC-ventromedial PFC-amygdala inhibitory circuitry during attempts to down
regulate negative emotion (2
), the present findings suggest that too much
VLPFC activity is problematic for individuals who are depressed, and a) relates to an inability to down-regulate negative emotion appropriately, resulting in the experience of excessive negative affect (2
), b) relates to a keen ability to inhibit positive affect, resulting in a reduced ability to experience pleasure (supporting evidence herein), and c) may make the experience of any degree of positive emotion an effortful task (1
RVLPFC activity during attempts to dampen positive affect is selectively related to changes in anhedonia; as activation in the same region during attempts to suppress negative affect did not predict reduction in anhedonia, and RVLPFC activity during the “positive suppress” condition did not predict change in general symptoms of MDD as measured by the HRSD.
Ultimately, the present results suggest that we have the ability to inhibit positive affect, whether intentional or unintentional. Effortful resistance to this inhibitory effect may be an important positive predictor of the transition from anhedonia to euthymia. When treating anhedonia, it may not be sufficient to increase the number/frequency/duration
of pleasurable activities a depressed individual engages in, as espoused by behavioral activation therapies. Anhedonic individuals may also need training in how not
to subvert the generation/experience of positive emotions once they are in contact with
positive stimuli. Anhedonic individuals may benefit from learning to recognize, and mentally argue against, pleasure-dampening thoughts/appraisals/behaviors (e.g. engaging in an activity but telling oneself “this activity won’t be enjoyable,” or flatly thinking “I don’t deserve a reward” or “my achievement isn’t really that great”) before
the initiation of and during
the engagement of a potentially rewarding activity (22
Recent advances in social cognition/affective neuroscience research, such as the emergence of the concept of “positive empathy” (20
)—the tendency to vicariously share in the positive emotion of another person (i.e. “empathic happiness”), or the tendency to use positive emotion as a means to cheer up someone who is in a negative or neutral mood state (i.e. “empathic cheerfulness”)—may provide a useful framework for developing novel treatments for anhedonia. Incorporating findings from recent empathy research, a behavioral therapist working collaboratively with an anhedonic individual could engage in any of the following activities with his/her client to augment traditional cognitive behavioral and/or dialectical behavioral techniques: a) engage the client in pleasurable activities in-session
to reveal dampening tendencies, and then actively implement/practice positive empathy and savoring techniques to disrupt such tendencies (e.g. watch a video excerpt together and then collaboratively reflect on/share in/discuss the most enjoyable features of the stimulus/activity from the point of view of the client and
therapist—a strategy that should also model/teach/encourage the client to derive personal pleasure even from pedestrian activities); b) the therapist can remind/teach the client that different positive emotions exist (e.g. joy, contentment, etc.), and the dyad can work to increase the amount of time the client spends in each
positive emotional state—i.e. not just 1 or 2 to the exclusion of others—via the development of an individualized “pleasurable activities” list that will help the client to generate ideas about and choose activities that will lead to the experience of a particular target positive emotion (e.g. joy vs. gratitude vs. interest), or set of positive emotions, that are “under-used” or even “foreign” to the client; c) the dyad can also work to decrease positive emotion inhibition in the client by increasing his/her ability to vicariously experience positive emotion on a global level via adding simple practices to their daily life such as soliciting
positive information from others on a regular basis (e.g. “tell me something good that happened to you
today”), or by doing something good for another person or the planet (e.g. volunteering, recycling, etc.) (23
). Mastering any one of these skills may increase well-being and combat the development/maintenance/recurrence of anhedonia.
There are two main limitations that should be noted. First, the absence of a placebo control group does not allow us to differentiate between specific and non-specific drug responses. It remains unknown to what extent the MDD group might have improved independent of drug treatment. Furthermore, the depressed group and the control group may have differed in terms of hedonic decoding ability. Though our button press accuracy data provides some evidence to the contrary, our data could be limited by a ceiling effect. Further studies will need to be conducted to more rigorously rule this factor out.