Clinical profile major depressive disorder:

It is an episodic disorder because symptoms tend to be present for a period of time and then clear. People with persistent depressive disorder are chronically depressed. Clinical profile:

The symptoms do not clear for more than 2 months at a time. Bipolar disorders are not present. Women are more likely than men to develop a depressive disorder. The prevalence of MDD is about 16%. The prevalence of dysthymia is about 2.5%. Social-economic status is an important factor in the prevalence of depression. Season affective disorder refers to a depressive episode during two consecutive winters. The comorbidity of a depressive disorder is high.

There are three types of bipolar disorders. The bipolar I disorder, the bipolar II disorder and the cyclothymic disorder. A depressive episode is not required for the bipolar I disorder.

Mania is a state of intense elation, irritability or activation accompanied by other symptoms. There is a flight of ideas. Hypomania involves a change in functioning that does not cause serious problems. To be diagnosed for bipolar I disorder, a single episode of mania must occur and this mustn’t be explained by another disorder. To be diagnosed for bipolar II disorder, a person must have had one depressive episode and one episode of hypomania. To be diagnosed with cyclothymic disorder, the symptoms must be present for at least two years.

Clinical profile manic and hypomanic episodes:

For manic episodes, the symptoms last one week and require hospitalization. The symptoms also cause significant distress. For a hypomanic episode, the symptoms last for at least four days. There are clear changes in behaviour, but there is no impairment. People that experience mania tend to be less creative.

Clinical profile cyclothymic disorder:

The symptoms do not clear for more than 2 months at a time and the symptoms cause significant distress.

The prevalence of bipolar I disorder is very low (0.6%), just as for the bipolar II disorder (0.4% - 2%) and the cyclothymic disorder (4%).

Bipolar disorder is very heritable. There is no specific gene for a mood disorder. The serotonin transporter gene appears to be related to MDD. A weaker serotonin system may result in a greater likelihood to experience depression after a major life event.

Norepinephrine, dopamine and serotonin may play a role in mood disorders. Mood disorders could be caused by changes in receptors that respond to the presence of neurotransmitters. The functioning of dopamine might be lowered in people with depression and increased in people with bipolar disorder. People who are vulnerable to depression may have less sensitive serotonin receptors.

Episodes of MDD are associated with changes in emotion regulation and experiencing brain systems. The amygdala helps assess how salient and emotionally important a stimulus is. Activity in the amygdala is elevated in MDD. MDD is also associated with greater activation of the anterior cingulate and diminished activation of the hippocampus, dorsolateral prefrontal cortex and the striatum. The striatum is important for reward-based learning. People with a depressive episode might have a poor cortisol regulation. Dysregulation in cortisol predicts a more severe course of illness for bipolar disorder and MDD.

Negative live events, childhood adversity, lack of social support, family criticism and an excessive need for interpersonal reassurance predict the onset of depressive episodes. Some people are more vulnerable to stress and this can explain the differences in depressive episodes between people. Social support is a buffer against the effect of severe stressors. Expressed emotion is a family member’s critical or hostile comments toward or emotional overinvolvement with the person with depression. High expressed emotions predicts relapse in depression.

Neuroticism is a personality trait that involves the tendency to experience frequent and intense negative affect and predicts the onset of depression. In cognitive models, cognitions are seen as the most important force driving the depression. There are three main cognitive theories of depression:

1. Beck’s theory
   Depression is associated with a negative triad (negative views of the self, the world and the future). This leads to a negative schema. The negative schemas cause cognitive biases which can lead to depression.
2. Hopelessness theory
   The most important trigger of depression is hopelessness, which is the belief that desirable outcomes will not occur and that there is nothing a person can do to change this. People who believe that negative events occur because of stable and global attributes are more likely to become hopeless.
3. Rumination theory
   Rumination is a tendency to repetitively dwell on sad experiences and thoughts. Women tend to ruminate more than men. Rumination may lead to depression. Rumination may occur because it can be evolutionary adaptive to dwell on negative events to solve problems. Rumination may also occur because of an inability to control the focus of thoughts.

Reward sensitivity and sleep deprivation predict increases in manic symptoms.

Psychological treatment of bipolar disorder can supplement medication. Psychoeducational approaches can help people adhere to treatment with medications. Lithium is used as medication for people with bipolar disorders. If lithium does not work, antipsychotic or antiseizure medication can be used.

Suicide involves behaviours that are intended to cause death and actually do so. Non-suicidal self-injury involves behaviours that are meant to cause immediate bodily harm but are not intended to cause death.

People with psychological disorders are more likely to commit suicide. Heritability is about 50% in suicide. Serotonin dysfunction is relevant to violent suicide. Social factors (e.g: economic recession) influences suicide rates. Social isolation and a lack of belonging are among the most powerful predictors of suicidal ideation.

Suicide can be prevented by actively talking about it and treating psychological disorders. Cognitive behavioural therapy is effective in reducing suicidality.