Mood Disorders: Major Depressive Disorder & Bipolar Type 1

Mood Disorders (AKA Affective Disorders) – a collection of psychiatric conditions that involve a pervasive distortion of one’s emotional state or affect. This should not be confused with normal fluctuations in mood. Everyone has periodic, mild changes in their affect as a result of their circumstances. Mood disorders have more extreme changes in mood that are often unrelated to an individual’s circumstances. However, mood disorders are characterized by periods of normal or near-normal affect and function in between more severe mood “episodes.”


Euthymia can be thought of as a neutral or “normal” mood. This is when a person isn’t particularly happy or sad. Psychiatrically healthy individuals spend most of the time in a euthymic state, but a “normal” patient will have times when they feel happy or sad. In certain circumstances (stressful situations, winning the lottery …) a healthy individual may even have transient feelings of elation or mild depression. However, these emotions do not lead to a loss of function and do not persist. Changes in affect become pathologic when extreme emotions are felt, these feelings persist and a loss of function is involved.


Mood can be thought of as a continuum ranging from extremely happy (mania with psychosis) to extremely sad (depression with psychosis and/or suicidal ideation). Mood disorders can primarily be differentiated based on where they lie on this continuum.

Mood Disorder Continuum Bipolar Type 1 2 Major Depressive Disorder Adjustment Cyclothymia Dysthmia Bereavement Mania
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Depression can involve a loss of interest in previously pleasurable activities (AKA Anhedonia), low self-esteem, hopelessness and fatigue as well as changes in sleeping patterns, libido, appetite and/or the ability to concentrate. Moderate to severe cases can cause a Loss of Function which inhibits a person’s ability to work or have a healthy family/social life. In severe cases depression can lead to suicidal ideation or psychosis (delusions, hallucinations…).


Usually when somebody says a person has depression what they really mean is that person has Major Depressive Disorder (MDD) and they don’t want to waste all of those extra syllables. So Major Depressive Disorder gets shortened to Depression. But you need to recognize that depression is as emotion and MDD is a medical diagnosis with specific criteria.


Major Depressive Disorder (MDD)a depressive disorder with very specific DSM criteria. These criteria involve a certain number of symptoms over a specific time period, but these details are beyond the scope of the USMLE Step 1 medical board exam so I will not cover them. All you need to know is that MDD involves having multiple moderate to severe depressive symptoms more often than not for at least a couple weeks. We will cover treatments in a later section.


Suicide is most often associated with Major Depressive Disorder, but can also be the result of other psychiatric illnesses that have a depressive component (like Bipolar Disorder or Adjustment Disorder), borderline personality disorder, psychosis, or substance abuse. Suicidal Ideation is when a patient frequently has thoughts of wanting to kill themselves, but has not actually attempted suicide……yet. You need to ask every patient with psychiatric symptoms about suicidal ideation (and homicidal ideation) at every visit. If the patient has the intent to commit suicide and a plan for doing so they need to be hospitalized. In some cases, a patient like this might need to be Baker Acted against their will. If a patient has thoughts of suicide, but has no plan they can be treated as an outpatient.


Recognizing depressive symptoms is pretty easy. However, making a diagnosis is a bit tougher because there is a long differential diagnosis for depression. In order to receive a diagnosis of MDD, the patient’s symptoms cannot be better explained by another medical condition or substance (such as medications or street drugs). The abuse of things like alcohol or benzos can cause depressive symptoms. Alternatively, withdrawal from stimulants like cocaine can cause depressive symptoms. There are also numerous general medical conditions that need to be considered. Hypothyroidism and anemia can frequently present with depressive symptoms, but they will usually give you clues that clearly point towards those diagnoses. For example, pale skin or laboratory results in anemia and cold intolerance or skin/hair changes in hypothyroidism.


There are also numerous psychiatric illnesses that can present with depressive symptoms. On the exam you have to keep an eye out for clues that make one diagnosis more likely than another. Often the severity, duration of symptoms and the presence or absence of acute stressors are the most important factors to consider.


Dysthymia – a milder prolonged version of MDD. These patients have depressive symptoms for more than 2 years, but they are not severe enough to cause a loss of function or suicidal ideation.


Adjustment Disorder (“Situational Depression”) – the lack of the ability to adjust to an acute stressor that leads to depressive symptoms that are out of proportion to the situation. These symptoms can be severe enough to lead to a loss of function and suicide. This disorder usually resolves when the stressor is removed or resolves spontaneously over a few month period as the person is able to adapt to the new situation. Examples of acute stressors would include marital problems, moving to a new city, being diagnosed with a fatal disease or getting fired.


Normal Bereavement – a normal response to a severe stressor or personal tragedy. This most often involves grief following the loss of a loved one. These patients have mild to moderate depressive symptoms, but can have short periods of euthymia or even happiness during their depressive episode (AKA the symptoms “wax and wane”). The patient’s mood should slowly improve overtime and the depressive symptoms should largely resolve over the course of a year. Normal bereavement should not be debilitating and the patient should be able to function at home/work/school. These patients usually do not require pharmacologic treatment. Pathologic Grief is either prolonged (lasts more than 1 year) or more extreme (loss of function, suicide …).


Post-Partum Depressive Symptoms – a range of mood disorders seen in OB patients after delivery. Post-Partum Blues is a common mild form of depression that usually resolves spontaneously within a couple weeks. Post-Partum Depression is a more severe and last more than a couple weeks. It can lead to a loss of function and ambivalence towards the child. To prevent neglect of the child you should make sure somebody else can help care for the child and the mother is usually treated with SSRIs. Post-Partum Psychosis is a rare disorder where the mother may actively wants to harm the infant, because she thinks the child is evil. The mother requires inpatient treatment and will usually be treated with antipsychotics.


Mania – a period of extremely elevated mood (AKA Euphoria) & excessive energy despite a lack of sleep. Manic individuals have rapid speech and talk much more often than they normally do. They often have difficulty concentrating and are easily distracted. Mania may be accompanied by disinhibition and risky or inappropriate behavior. It can involve irritability and delusions of grandeur (a belief that they are famous, influential, powerful or a genius). Severe mania is sometimes accompanied by psychosis. Manic patients have an almost complete loss of function and require hospitalization. Hypomania is a milder version of mania that usually does not require hospitalization. There is no psychosis in hypomania. Hypomania has less of an impact on function than mania, and in some cases hypomania can actually increase productivity.


Type I Bipolar Disorder (Formerly known as Manic Depression) = alternating periods of mania and moderate to severe depression followed by a return to normal functioning. However, the presence of a depressive phase is not required for a diagnosis to be made. A single episode of mania is enough for a diagnosis even before the inevitable depressive phase arises. We will discuss treatment options in a later section.


Type II Bipolar Disorder = alternating periods of hypomania and depression followed by a return to normal functioning.


Cyclothymia = alternating periods of hypomania and mild depression followed by a return to normal functioning.

ERRATA: I misspelled “Dysthymia” on the video so I tried to correct it by adding a pop up box on the video. Thanks to Youtube user “Gilbert Flowerface” for pointing out the error in a comment


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