Most people think of depression as a single condition, but in fact, depression falls into a category of mood disorders that comes in many varieties. It’s important to distinguish the type of depression, as different forms have different treatments.

Here are some examples:

Major Depression. These patients typically experience episodes when they have a constellation of both psychological (depressed mood, lack of interest, guilty feelings) and physical (insomnia, weight loss, low energy) symptoms that interfere with their daily functioning. They usually respond positively to antidepressant medicines, psychotherapy, or both.

Psychotic Depression. When depression becomes severe, patients can sometimes lose touch with reality, and believe their symptoms are a punishment or that others are conspiring against them. An antipsychotic medicine combined with an antidepressant can relieve such symptoms; electroconvulsive therapy (ECT) is also an option.

Bipolar Disorder. Also called manic-depressive disorder, patients with this condition suffer episodes of depression interspersed with manic episodes characterized by rapid thoughts and speech, euphoria, or irritability along with increased energy and impulsivity. A manic patient becomes psychotic and loses touch with reality. Lithium or other mood stabilizers, along with antidepressant medicines and psychotherapy, can be effective.

Minor Depression or Dysthymia. This is often a chronic form of depression with less severe symptoms that may not have as much of an impact on functioning.

Depressive Pseudodementia. Some older patients present to the doctor with what appears to be Alzheimer’s or dementia. A careful assessment may uncover underlying depression. Cognitive symptoms improve once the depression is properly treated.