Major Depressive Disorder

major depressive disorder (MDD)

Major depressive disorder (MDD) has the highest prevalence of any psychiatric illness: ~ 7% of adults in the US have had a depressive episode.
According to the DSM-5, the diagnosis requires at least 2 weeks of at least 5 of "D'SIG E CAPS" symptoms generally being present most of the day, nearly every day (if applicable).
Make note that 1 of the symptoms must be either be the "D" for depressed mood or the "I" for loss of interest in activities (anhedonia).

The full symptoms are as follows:

D for depressed mood (feelings of sadness, emptiness, hopelessness)
S for increased or decreased sleep
I for loss of interest in activities (anhedonia)
G for excessive guilt or feelings of worthlessness
E for loss of energy
C for loss of concentration (or indecisiveness)
A for increased or decreased appetite (or > 5% change in weight (gain or loss) in one month)
P for psychomotor retardation or agitation (this is observable by others; it's not just an internal feeling of being "run down").
S for suicidal ideations (either active or recurrent passive thoughts of death)

Medical/Iatrogenic Causes

Remind ourselves to rule-out medical or iatrogenic causes (eg, hypothyroidism or any slew of commonly prescribed medications can cause symptoms of depression and suicidality).

Differential Diagnosis

Persistent Depressive Disorder

Persistent depressive disorder (better known as dysthymia).
Involves at least 2 depressive symptoms that last at least 2 years in duration. It's generally considered to be milder but more refractory than major depressive disorder.

Major Depressive Disorder with Seasonal Pattern

Major depressive disorder with seasonal pattern (better known as seasonal affective disorder).
The MDD is restricted to a season (typically winter) and that it must occur in at least 2 consecutive years (and will typically occur consistently over a lifetime). Light therapy (in addition to buproprion and other MDD treatments) is helpful in the management of this disorder.

Peripartum Onset Depression

This mood disorder begins within 4 weeks of giving birth.
There is often a pre-existing mood disorder.
Symptoms range from severe depression to psychosis, called postpartum psychosis.
A milder form, called postpartum blues, is common, which may affect up to 85% of women for the first couple of weeks post-delivery.

Bereavement

Importantly (and contentiously) the DSM-IV established that a diagnosis of major depressive disorder couldn't be made in the setting of bereavement but the updated, DSM-5 does not include this exclusionary criteria.
Grief-related depression can be categorized as normal bereavement or a major depressive episode depending on whether the symptoms are considered consistent with normal grief or if they extend beyond that.

Board Review

Getting ready for boards? Review these concise, bulleted high yield reviews for your exam.

USMLE & COMLEX-USA

Nurse Practitioner (NP)

Nurse Practitioner Licensing Exam

Physician Assistant (PA)

Physician Assistant Licensing Exam

Neurology (ABPN)

American Board of Psychiatry & Neurology (ABPN) Exam

Internal Medicine (ABIM)

American Board of Internal Medicine (ABIM) Exam