2.4 Mood Disorders

Mood disorders make up a large share of TCO Knowledge statement K3 ("psychiatric disorders — eg, thought, mood, neurocognitive, personality, addictions") and are among the highest-yield content on the PMH-BC exam because they appear across nearly every care setting.

Major Depressive Disorder (MDD)

MDD requires at least 5 of 9 symptoms present during the same 2-week period, representing a change from previous functioning, with at least one symptom being depressed mood or loss of interest/pleasure (anhedonia). The mnemonic SIGECAPS captures the criteria: Sleep disturbance, Interest loss (anhedonia), Guilt/worthlessness, Energy loss/fatigue, Concentration difficulty, Appetite/weight change, Psychomotor agitation or retardation, Suicidal ideation — plus depressed mood itself. Symptoms must cause clinically significant distress or impairment and cannot be better explained by a substance, another medical condition, or normal bereavement.

Persistent depressive disorder (dysthymia) is a chronic form: depressed mood for most of the day, more days than not, for at least 2 years (1 year in children/adolescents), with at least 2 additional symptoms that are typically milder than full MDD but more enduring. A patient can have both — "double depression" — when an MDD episode is superimposed on underlying dysthymia.

Two additional DSM-5-TR mood diagnoses round out the depressive spectrum: disruptive mood dysregulation disorder (children and adolescents with severe, recurrent temper outbursts grossly out of proportion to the situation, occurring 3+ times weekly, with a persistently irritable mood between outbursts) and premenstrual dysphoric disorder (PMDD — significant mood symptoms in the final week before menses that improve within a few days of onset and are minimal in the week postmenses).

Bipolar I Disorder

Bipolar I requires at least one manic episode. A manic episode is a distinct period of abnormally and persistently elevated, expansive, or irritable mood and increased goal-directed activity/energy, lasting at least 7 days (or any duration if hospitalization is necessary), with at least 3 additional symptoms (4 if mood is only irritable). The mnemonic DIGFAST captures them: Distractibility, Indiscretion (risky behavior — spending, sexual, business), Grandiosity, Flight of ideas, Activity increase/psychomotor agitation, Sleep decreased need, Talkativeness/pressured speech. Mania causes marked impairment, may include psychotic features, and often requires hospitalization. A depressive episode is common in the course of bipolar I but is not required for the diagnosis — one manic episode alone is sufficient.

Bipolar II Disorder

Bipolar II requires at least one hypomanic episode plus at least one major depressive episode. Hypomania shares the same symptom list as mania but with two critical differences: it lasts at least 4 consecutive days (shorter than mania's 7), and it is not severe enough to cause marked impairment, does not include psychotic features, and does not require hospitalization — it is noticeable to others as a change in functioning, but the person often remains functional or even hyperproductive. A patient with bipolar II who ever experiences a full manic episode is reclassified as bipolar I.

Cyclothymic Disorder

Cyclothymic disorder involves numerous periods of hypomanic symptoms and numerous periods of depressive symptoms over at least 2 years (1 year in children/adolescents), present at least half the time, without a symptom-free period longer than 2 months — but the symptoms never meet full criteria for a hypomanic, manic, or major depressive episode. It is best understood as a chronic, lower-amplitude version of the bipolar spectrum.

Mania versus Hypomania — Comparison

Clinically Important Specifiers

DSM-5-TR allows specifiers to be added to a mood disorder diagnosis, and recognizing them changes both risk assessment and treatment planning (Chapters 3-4). "With psychotic features" indicates delusions or hallucinations accompany the mood episode — a marker of greater severity. "With anxious distress" flags a depressive or manic episode with prominent co-occurring anxiety symptoms, which is associated with higher suicide risk and often guides medication selection. "With seasonal pattern" describes a regular temporal relationship between episode onset and a particular time of year (most classically, depressive episodes in fall/winter). "With peripartum onset" applies when a mood episode begins during pregnancy or within 4 weeks postpartum and carries distinct safety considerations, including screening for postpartum psychosis, which is a psychiatric emergency given its association with risk to the infant.

For the exam, the fastest path to the correct diagnosis is to ask three questions in sequence: (1) Is there a manic episode present at all (duration ≥7 days or hospitalization)? If yes, it's bipolar I regardless of depressive history. (2) If no mania, is there a hypomanic episode (≥4 days) plus a major depressive episode? That's bipolar II. (3) If neither reaches full-episode criteria but the pattern is chronic (≥2 years) and fluctuating, consider cyclothymic disorder. Getting mania and hypomania correctly differentiated — especially the absence of psychosis and hospitalization in hypomania — is one of the most consistently tested distinctions on the PMH-BC exam.