The types of depression: one word for several distinct conditions

"Depression" is an umbrella. Underneath it sit several distinct conditions that share a core of low mood and lost interest but differ in how long they last, what triggers them, and how they are treated. Getting the type right matters, because the right treatment depends on it — antidepressants that help major depression, for example, can destabilise bipolar depression.

The types below are the ones clinicians distinguish most often. A screening cannot tell them apart — only a clinician can — but the PHQ-9 depression screening is a good first read on how heavy your symptoms are right now, whichever type is behind them.

The main types, one by one

Major depressive disorder (MDD)

The "classic" form: episodes of persistent low mood and lost interest lasting at least two weeks, heavy enough to disrupt daily life. Episodes can recur across a lifetime.

Persistent depressive disorder (dysthymia)

A lower-grade but long-running depression lasting two years or more. Less intense than a major episode, but so constant it can feel like a personality trait rather than an illness.

Bipolar depression

The depressive side of bipolar disorder. It can look identical to major depression, which is why it is so often missed — but it needs different treatment, so a history of high or wired periods is worth flagging.

Seasonal affective disorder (SAD)

Depression that follows the calendar, typically deepening in autumn and winter as daylight shrinks and lifting in spring. Light therapy is a first-line treatment alongside the usual options.

Postpartum (peripartum) depression

Depression during pregnancy or in the year after birth — more than the short-lived "baby blues", often laced with anxiety and guilt. Common, treatable, and not a reflection of being a parent.

Premenstrual dysphoric disorder (PMDD)

A severe, cyclical mood crash in the days before a period, easing once it starts. Distinct from ordinary PMS in its intensity and its disruption to life and relationships.

Situational depression (adjustment disorder)

A depressive reaction to a specific stressor — loss, divorce, job change — that exceeds ordinary sadness. Often eases as circumstances settle, but can tip into major depression.

See also the depression overview and the full symptoms guide.