“As an undergraduate student in psychology, I was taught that multiple personalities were a very rare and bizarre disorder. That is all that I was taught on ... It soon became apparent that what I had been taught was simply not true. Not only was I meeting people with multiplicity; these individuals entering my life were normal human beings with much to offer. They were simply people who had endured more than their share of pain in this life and were struggling to make sense of it.”
― Deborah Bray Haddock, The Dissociative Identity Disorder Sourcebook
Dissociative Identity Disorder (DID) is frequently comorbid with depressive disorders and bipolar and related disorders, previously known collectively as mood disorders.
Depressive disorders include disruptive mood dysregulation disorder, major depressive disorder (specify if single episode or recurrent episode and mild, moderate, or severe with options for with psychotic features, in partial remission, in full remission, or unspecified), persistent depressive disorder (dysthymia) (specify if: in partial remission or in full remission; early onset or late onset; with pure dysthymic syndrome, persistent major depressive episode, intermittent major depressive episodes with current episode, or intermittent major depressive episodes without current episode; mild, moderate, or severe), premenstrual dysphoric disorder, substance/medication-induced depressive disorder (specify if onset during intoxication or onset during withdrawal), depressive disorder due to another medical condition (specify if with depressive features, with major depressive-like episode, or with mixed features), other specified depressive disorder, and unspecified depressive disorder. Major depressive disorder and persistent depressive disorder (dysthymia) both have specifiers for: with anxious distress (mild, moderate, moderate-severe, or severe), with mixed features, with melancholic features, with atypical features, with mood-congruent psychotic features, with mood-incongruent psychotic features, with catatonia, with peripartum onset, and with seasonal pattern.
Bipolar and related disorders include bipolar I disorder (specify if current or most recent episode manic (mild, moderate, severe, with psychotic features, in partial remission, in full remission, unspecified), current or most recent episode hypomanic (in partial remission, in full remission, unspecified), current or most recent episode depressed (mild, moderate, severe, with psychotic features, in partial remission, in full remission, unspecified), or current or most recent episode unspecified), bipolar II disorder (specify if current or most recent episode hypomanic or depressed, in partial remission or full remission, and mild, moderate, or severe), cyclothymic disorder (specify if with anxious distress), substance/medication-induced bipolar and related disorder (specify if onset during intoxication or onset during withdrawal), bipolar and related disorder due to another medical condition (specify if with manic features, with manic- or hypomanic-like episode, or with mixed features), other specified bipolar and related disorder, and unspecified bipolar and related disorder. Bipolar I disorder and bipolar II disorder both have specifiers for: with anxious distress (mild, moderate, moderate-severe, or severe), with mixed features, with rapid cycling, with melancholic features, with atypical features, with mood-congruent psychotic features, with mood-incongruent psychotic features, with catatonia, with peripartum onset, and with seasonal pattern.
Depressive disorders are characterized by "sad, empty, or irritable mood accompanied by somatic and cognitive changes that significantly impact the individual's ability to function." The disorders within this category are differentiated by "duration, timing, or presumed etiology."
Symptoms of major depressive disorder include 5 or more of the following: depressed mood; significant weight loss or gain or change in appetite; insomnia or hyposomnia; observable restlessness or slowed movements; fatigue or loss of energy; feelings of worthlessness or guilt; a diminished ability to think, concentrate, or make decisions; recurrent thoughts of death or suicide.
Symptoms of dysthymia are persistent and include a depressed mood and two or more of the following: poor appetite or overeating; insomnia or hyposomnia; low energy or fatigue; low self-esteem; poor concentration or difficulty making decisions; feelings of hopelessness.
Bipolar and related disorders are similar to both depressive disorders and schizophrenia spectrum and other psychotic disorders in terms of symptoms, family history, and genetics.
Bipolar I disorder is classic "manic-depressive disorder" or "affective psychosis." Emphasis is on the full manic episode. However, most individuals with Bipolar I disorder will also experience full depressive episodes. In contrast, bipolar II disorder requires one full depressive episode and one full hypomanic episode.
Bipolar II disorder used to be thought of as a milder version of bipolar I disorder, but many individuals with bipolar II disorder spend a lot of time in depressive episodes, and the disorder is associated with serious impairment in work and social functioning.
Cyclothymic disorder is more of a truly milder version of the bipolar disorders because it is characterized by at least 2 years of both hypomanic and depressive episodes without ever fulfilling the criteria for mania, hypomania, or major depression.
A manic episode is defined as "a distinct period of abnormally and persistently elevated, expansive, or irritable mood and abnormally and persistently increased goal-directed activity or energy." A hypomanic episode is similar to a manic episode but lasts only 4 days instead of a week (though any length of episode counts as manic if it requires hospitalization). In contrast, a major depressive episode is defined by a depressed mood or loss of interest or pleasure in addition to another 4 out of 9 possible symptoms such as those specified in major depressive disorder.
All information taken from the DSM-5.
American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). http://dx.doi.org/10.1176/appi.books.9780890425596