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Mood disorders: Pathology review



Behavioral sciences

Psychological disorders

Mood disorders
Anxiety disorders
Obsessive-compulsive disorders
Stress-related disorders and abuse
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Personality disorders
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Psychological disorders review

Mood disorders: Pathology review


0 / 17 complete

USMLE® Step 1 style questions USMLE

17 questions

A 28-year-old woman comes to her physician complaining of low energy and an irritable mood for several weeks. She was recently accepted into a master's program and was ecstatic to begin in the fall semester. Once classes started, she began experiencing feelings of “worthlessness.” Her history is significant for self-described “mood swings,” which consist of several-week periods of productivity and improved mood, followed by several-week periods of fatigue, guilt, and depressed mood. She takes no medications. She drinks 2-3 glasses of wine on the weekends. Physical examination is within normal limits.  Mental status examination reveals a visibly tired woman who often needs questions repeated due to inattentiveness. Which of the following is the most likely diagnosis?  


Content Reviewers:

Antonella Melani, MD

54 year old Liam presents to the clinic because of a persistent feeling of sadness, ever since he got divorced and his former wife moved out with their son, five months ago.

Liam mentions that he doesn’t enjoy anything anymore, not even listening to his favorite songs.

However, he does briefly cheer up every time his son visits him.

Upon further questioning, Liam admits to gaining a lot of weight recently, and feels like he can’t stop eating.

When you ask Liam about his sleep habits, he tells you that he often sleeps more than 13 hours a night, but still feels tired when waking up.

Next to him, 25 year old Elfie is brought to the clinic by her father, who is worried that Elfie has not slept much for the past 5 days, but still seems overly energetic.

Her father is also furious because two days ago Elfie maxed out her credit cards shopping for clothes.

Elfie interrupts him to say that nobody understands her, because she’s more intelligent than everyone on this planet!

Then, Elfie starts pacing around the room as she continues to speak rapidly and jumps from one topic to another.

She denies experiencing any psychotic symptoms, like hearing or seeing things that others don't.

Finally, Elfie also mentions that she hasn't stopped going to work or interacting with her colleagues these past five days.

Okay, based on the initial presentation, both Liam and Elfie seem to have some form of mood disorder.

Many of us can have days when we feel sad or overly happy.

But with mood disorders, these emotional variations can become impossible to control, sometimes even to the point where they interfere with day-to-day activities like working, studying, eating, and sleeping.

Now, the main risk factors seem to include having a family history or experiencing a personal trauma.

However, the underlying cause is poorly understood; for your exams, what you need to remember is that there’s usually an imbalance of the neurotransmitters serotonin, norepinephrine, and dopamine, which normally help regulate mood, reward-motivated behavior, appetite, and sleep.

Mood disorders can be seen as a spectrum of emotional states that range from depression or extreme sadness to mania or excessive excitement.

So at one end of the spectrum, we have depressive disorders, which are characterized by depressive episodes that consist of nine key symptoms.

First, a person feels depressed or sad, hopeless, and may lack a sense of purpose most of the day, every day.

Remember that in children, this can manifest as irritability.

Second, there’s anhedonia, which means a diminished interest in everyday activities that used to be really pleasurable, like no longer enjoying hobbies like cooking or gardening.

Third is either an increase or decrease in appetite, which can eventually lead to weight gain or loss.

Fourth is sleeping too much or too little compared to what used to be normal for that person.

Fifth, the affected person may lack energy and feel extremely tired or chronically fatigued.

Sixth is difficulty concentrating, while seventh can be psychomotor retardation or slowing down of a person’s thought, emotional reactions, and movements.

Eight involves having persistent feelings of worthlessness and excessive guilt.

And finally, ninth, a person might have recurrent thoughts of death or suicidal ideation with or without a specific plan.

Okay, now, the most high yield depressive disorder is major depressive disorder.

This is characterized by depressive episodes that last for at least two weeks and include five of these nine key symptoms, with at least one of them being the depressed mood or anhedonia.

Now, major depressive disorder has a few subtypes, which include depression with atypical features; major depressive disorder with seasonal pattern; major depressive disorder with psychotic features; and major depressive disorder with peripartum onset.

For your exams, remember that they all share the same symptoms of depressive episodes, but are distinguished by having unique features or a specific trigger.

Depression with atypical features, sometimes referred to as atypical depression, is the most common subtype.

Now, in addition to depressive episodes, this type of depression is mainly characterized by two unique features.

One is mood reactivity, which is when individuals transiently have an improved mood in response to pleasurable or positive events.

And the other is rejection sensitivity, which is when individuals feel anxious and overreact at the slightest evidence of rejection.

Other key clues include hyperphagia or increased appetite, and hypersomnia or excessive sleepiness.

Additionally, a very unique feature is leaden paralysis, which is an unusual heavy feeling in the arms and legs, and is often associated with a feeling of fatigue.

Next up is major depressive disorder with seasonal pattern, previously called seasonal affective disorder.

Here, symptoms appear during cold seasons due to a decreased exposure to sunlight.

In fact, sunlight seems to be associated with boosting mood and improving symptoms of depressive episodes.

For your test, remember that diagnosis requires at least two depressive episodes to have occurred during cold months for the past two years, with no history of depressive episodes during warmer seasons.

There’s also major depressive disorder with psychotic features, previously known as psychotic depression.

This is when depression is accompanied by psychotic features, including illusions or misperception of sensory stimuli, as well as hallucinations or perceiving something that’s not real.

It’s important to remember that these features are mood-congruent, meaning that their content is usually aligned with the person’s low mood, and may often center around guilt, punishment, inadequacy, illness, or death.

Another key fact here is that the psychotic features occur only during episodes of major depression.

This is a key difference with schizoaffective disorder, which involves the presence of psychotic symptoms for at least two weeks but without having a depressed mood.

Next is major depressive disorder with peripartum onset, previously known as postpartum depression, which has an incidence rate of 10 to 15%.

Peripartum onset means that it most often happens during pregnancy or four to six weeks following parturition or delivery, but keep in mind that it can occur anytime within and no later than the first year after delivery.

And that’s a high yield fact!

Now, the exact cause isn’t understood, but it’s likely related to hormonal changes, along with the emotional and physical stress that can accompany the birth of a child.

For your exams, you should be able to differentiate major depressive disorder with peripartum onset from postpartum blues, which is way more common!

In fact, the incidence rate goes from 50 to 85%, and symptoms may include depressed mood, crying outbursts, and lethargy or fatigue.

But the most important clue is that postpartum blues usually start 2 to 3 days after delivery, and typically resolve within 10 days.

Another high yield mood disturbance that can occur during the peripartum period is postpartum psychosis, which instead is way less frequent, with an incidence rate of about 0,1%.

Symptoms of postpartum psychosis include illusions, hallucinations, as well as suicidal ideation, or thoughts of harming their baby.

For your exams, remember that postpartum psychosis is often associated with an underlying psychotic or bipolar disorder, or a recent medication change, and occurs more commonly in first-time pregnancies and those with a family history.

All right, back to depressive disorders, another high yield one is persistent depressive disorder, previously known as dysthymia.

What you need to remember here is that it is milder, and must include at least two of the following: a change in appetite, a change in sleep, fatigue or low energy, reduced self-esteem, decreased concentration or difficulty making decisions, and a feeling of hopelessness or pessimism.

Now, the key to diagnose persistent depressive disorder is that these symptoms need to persist over longer periods of time, specifically two or more years in adults and one or more years in children or adolescents.

And remember that individuals with persistent depressive disorder may have remission periods where they have no depressive episodes.

However, what’s characteristic is that these remission periods never last for more than 2 months.

Now, before diagnosing a depressive disorder, it is essential to differentiate it from grief, which is a feeling of deep sorrow in response to physical or emotional loss.

For instance, grief can be experienced when losing a loved one, as well as when a person learns that they have a terminal illness, and this is completely normal..

Now, according to the Kübler-Ross model, grief can be divided into five stages, which include denial, anger, bargaining, depression, and acceptance.

Keep in mind that these can happen in any order.

During denial, the person may deny or reject the reality of their loss or illness.

During anger, they might become angry with themselves or others, such as a caregiver, for no reason.

Bargaining is when the person tries to make a promise or deal, usually with a higher power like their God, in return for relief from their pain or to prolong their life.

Depression is when the person realizes the full impact of their loss or illness, and that might make them cry, refuse meals, become withdrawn, or stop sleeping.

Finally, acceptance is when the person makes peace and comes to terms with the reality of their situation.

Other high yield symptoms that can be normally experienced by a grieving individual are intense sadness and yearning for their loved one, as well as feeling guilt, anxiety, and sometimes somatic symptoms, such as headaches or chest pain.

Some individuals may even experience auditory or visual hallucinations of the deceased person, as well as thoughts of dying that are limited to joining the deceased one.

And that’s a high yield fact!

Now, the duration of grief can vary widely, but normally resolves within 6 to 12 months, as the individual progressively starts feeling better.

On the other hand, when grief becomes extreme, it’s called persistent complex bereavement disorder.

This means that there’s obsessive preoccupation or yearning for a deceased one, which significantly impairs daily functioning.

And this needs to persist for at least 12 months for adults or 6 months for children.

For your exams, note that during the course of persistent complex bereavement disorder, criteria for a major depressive episode can also be met.


Mood stabilizers are a class of medications used to treat mood disorders, such as bipolar disorder and persistent depressive disorder. There are several different types of mood stabilizers, including lithium, valproate, and carbamazepine.

Nursing considerations for patients taking mood stabilizers include monitoring for side effects, dosing, educating patients about medication, and adherence. It is also crucial that nurses know any potential drug interactions and carefully monitor patients for any changes in their mood or behavior.

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