Unipolar depression has many possible underlying causes. First, stressful events often occur before an individual experiences unipolar depression. Biological factors include genetics, biochemical factors, brain anatomy, and brain circuits. Upon examination of the family tree of individuals who suffer from unipolar disorder, researchers found that up to 20% of their family struggled with it as well in comparison to 10% of the general population, showing a genetic relationship.
Twin studies have shown a 46% incidence of unipolar depression in an identical twin whose sibling suffered from unipolar depression, and only a 20% incidence in fraternal twins, and several genes have been associated with the occurrence of the disorder. The first biochemical factor playing a part in unipolar depression is low activity of the neurotransmitter chemicals norepinephrine and serotonin. Overproduction of the hormone cortisol, normally produced during stressful situations, has also been linked to unipolar depression, along with some tentative theories about chemical deficiencies within neurons.
The brain anatomy factors beginning to be seen as influencing unipolar depression are the dysfunction of brain circuits involving the prefrontal cortex, hippocampus, amygdala, and Brodmann Area 25. First of the psychological factors influencing unipolar depression is that influenced by Freud and Abraham: it occurs when relationships leave an individual feeling unsafe and insecure. Next, the dwindling of positive rewards in life may reduce constructive behaviors, causing a circle that may be a factor in unipolar depression. Third, viewing events in negative ways may lead to having this disorder.
Finally, gender, cultural, and ethnic background may also play a part in the development of unipolar depression. Much of the research into the causes for bipolar disorder is biological. Low serotonin combined with low norepinephrine is thought to cause unipolar depression, but low serotonin and norepinephrine over activity has been linked to bipolar disorder. Transportation of ions in the brain happening too quickly and slowly is theorized to cause depression and mania, and abnormal brain structures such as a small basal ganglia or cerebellum has been connected to bipolar disorder.
Finally, family pedigree and genetic linkage studies have shown a relationship between genetics and a predisposition to developing bipolar disorder. Unipolar depression and bipolar disorder are both mood disorders, however individuals suffering from them exhibit different symptoms. Unipolar depression is when an individual only suffers from depression, and they return to a nearly normal mood when it lifts. Symptoms can range from moderate to severe, although the moderate symptoms may still not allow the individual to experience much pleasure.
Crying spells often result from unipolar depression because of the feelings of being miserable, empty, and humiliated. Sense of humor reduces and it becomes difficult to experience pleasure, sometimes becoming incapable of experiencing pleasure at all. Unipolar depression can also cause anxiety, anger, and agitation. Motivational symptoms include lack of desire to complete everyday tasks, and a reduced interest in life and desire to commit suicide are common.
Depressed people may additionally become less active and productive, stay in bed, speak more slowly, spend more time alone, and hold extremely negative views of themselves. Unipolar depression can cause physical symptoms, the most common being a reduction of appetite and sleep. Those with bipolar disorder experience the same symptoms as unipolar depression during their depressive periods, but also experience manic periods bring a whole new set of symptoms. The first symptom of mania is having feelings that are not proportional to the triggering event.
Next, manic episodes bring about a need for excitement. Many projects may get started with little of them finished, and there is no awareness of the overwhelming nature of social style. Behavior during a manic episode often involves quick movements, loud speech, and odd behavior such as giving money to strangers or getting involved in dangerous activities. Finally, mania also causes poor judgment and planning, inflated self-esteem, and extreme energy. Biological treatments for unipolar depression include electroconvulsive therapy, or ECT, antidepressant drugs, and brain stimulation.
ECT delivers volts of electricity through the brain, causing brain seizures that can be therapeutic. MAO inhibitors are an example of antidepressant drugs used to treat unipolar depression; they block the breakdown of norepinephrine, increasing its activity and reducing symptoms. Tricyclics block the neuron reuptake process, increasing neurotransmitter activity, and SSRIs can increase serotonin and norepinephrine activity. Vagus nerve stimulation, transcranial magnetic stimulation, and deep brain stimulation are all brain stimulation techniques also used to treat unipolar depression.
Psychodynamic treatments for unipolar depression include various methods of free association, and behavior treatments add pleasurable activities to a clients life, rewards pleasurable events, and trains clients in social skills. Cognitive treatment is a cognitive-behavioral therapy, using behavioral methods in combination with trying to change negative thinking. Finally, sociocultural treatments include interpersonal therapy, couple therapy, and cultural-sensitive approaches. Treatment for bipolar disorder includes the use of lithium, other mood stabilizers, and adjunctive psychotherapy.
Lithium and other mood stabilizers are more effective in treating manic episodes, though they also treat depressive episodes. However, exactly how they work is not fully known. Antidepressants can be used in combination with the mood stabilizers, but there is an unfavorable cost/benefit ratio for antidepressant treatment of bipolar depression when used alone. (S, Rosenquist, Ko, & Baldassano, 2004). Psychotherapy is used in addition to mood stabilizing medication to increase the likelihood of their success, but it is rarely effective as a treatment on its own.
In conclusion, bipolar disorder is like an extended version of unipolar depression, as those with bipolar disorder experience depressive symptoms in addition to their episodes of manic symptoms. There is not one blanket cause for either disorder; rather each individual case must be evaluated separately and receive its own treatment plan. Unipolar depression has more treatment options because therapy or medication is not always required, but a combination of medication and therapy is usually most successful in treating both bipolar disorder and unipolar depression.