Social anhedonia
Depressed patients lack the ability to form social bonds with others. Depressed patients who suffer from chronic stress such as having a low number of friends and social isolation are more likely to suffer from social anhedonia. In addition, depressed patients who consumed cocaine or amphetamine have even less social interaction due to an overwhelming release of dopamine that well-activated their social reward system. Besides, depressed patients encounter social skill deficits due to sufficient cognitive resources to process incoming signals. Self-focused depressed patients have difficulties in interpersonal relationships and responsiveness to social contact as they protect themselves from anticipated disappointment, rejection, and social exclusion.
In addition, depressed patients are less likely to gain pleasure from interpersonal interaction accompanied by decreased responsibility for the social reward system. When Brain-derived neurotrophic factor (BDNF) that signals in the mesolimbic dopamine pathway is blocked by NAcc, it triggers susceptibility to social anhedonia: NAcc receives glutamatergic projection from the prefrontal cortex or hippocampus, etc, modulation of thlamo-NAcc projection, promoting susceptibility and social avoidance. The μ-opioid receptor (MOR) deactivation in NAcc is another factor that leads to social anhedonia. Last but not least, the requirement for stronger activation of the medial prefrontal cortex (mPFC) and low connectivity between NAcc mPFC are other factors that lead to social anhedonia. Depressive patients exhibited greater mPFC activation in response to mutual liking (ex: being loved by someone they also liked). Correspondingly, depressed patients have trouble sending neural responses from the ventral striatum within decreased mPFC function during social reward.
Social rejection
50% of depressed patients demonstrate increased social rejection sensitivity. Peer rejection is a threat to self-preservation because it is associated with negative social evaluation, giving rise to self-conscious emotion and social exclusion.
On the neuronal basis, impaired emotional response toward social rejection is due to an altered opioid activity in the amygdala contributed from stress, including activation of the μ-opioid receptor and dependent upon blood-oxygen-level, involving in alleviating physical and emotional pain as μ-opioid failed to release neurotransmitters that regulate our mood. Also, depressed patients exhibited increased activation of insulin response to peer rejection, revealing that they respond more strongly to social exclusion than normal. On the other hand, depressed patients' low vulnerability is the failure to overcome significant negative emotional responses of the amygdala.
Avoidance of social competition
Depressed individuals avoid competition when chances of winning are low, reducing emotional pain and damage caused by potential loss. Depressed people feel that they are losing the competition for acceptance and support.
Social competition avoidance is associated with high reactivity of stress and emotion, which as mentioned earlier, may be due to the deactivation of μ-opioid receptors in the amygdala. Apart, failure to obtain rewarding social pleasure from entering a competition due to reduced response to the reward pathway may also contribute to the avoidance of competition among depressed individuals. This may be due to altered activity in the lateral dorsal habenula that inhibits dopamine from binding to dopamine receptors among neurons. In addition, as mentioned above, high-stress hormone cortisol levels destroy connections between neurons, blocking neurotransmitters from transcription.
Economic Burden
The economic burden of depression is extremely high, approximated at 83.1 billion in the United States in 2000. Of the total costs for depression estimated in the United States in 2000, 31% was related to direct expensive medical costs, Average costs per patient, including medical services (diagnosis), and antidepressant and antipsychotic/antimanic drugs cost. 7% was related to suicide-related mortality costs, including future earning value, human capital value, and potential reparation for landlords. Last but not least, 62% was related to low productivity workplace costs. Absenteeism due to illness and disability, and reduced productivity while presenteeism of individuals with depression attributed to workplace loss.
