A mood disorder is a mental health issue wherein the patient experiences emotional ups and downs either in a way that is more pronounced than one would expect in a given situation or for no apparent reason at all. A mood disorder is not when someone is sad after a death or happy because of a new job, as these are situations and responses that one would reasonably expect. The type and severity of symptoms will vary widely from patient to patient, making effective treatment a process of trial and error. The most common types of mood disorders are depression (major and mild) and bipolar disorder (a mixture of depression and mania or “manic depression”). Studies suggest that genetics may play a partial role in causing a mood disorder. As with most mental illnesses, however, environmental factors, including childhood experiences, can also contribute to the development of a mood problem. Most patients with mood disorders benefit from a combination of both traditional “talk” therapy and psychoactive drugs. Cognitive behavioral therapy (CBT) is a common “talk” therapy used to treat patients with mood disorders. During CBT, a therapist helps the patient to identify behaviors and thought patterns that most often lead to problems and to develop alternative responses that do not trigger an inappropriate mood. Antidepressants are a class of prescription drug used to treat mood disorders. Typical examples include selective serotonin reuptake inhibitors (SSRIs), monoamine oxidase inhibitors (MAOIs), tricyclic antidepressants (TCSs) and serotonin-norepinephrine reupdate inhibitors. The majority of these medications manipulate the supply of or access to common neurotransmitters (chemicals) in the brain. For patients with bipolar disorder, lithium can be helpful in reducing the severity of symptoms associated with mania.