Unipolar vs Bipolar Mood Disorders

There are two primary classes of mood disorders: depressive disorders and bipolar disorders. Depressive disorders are unipolar – meaning that people typically only experience the spectrum of mood problems on one side (the depressed side). On the other hand, people with bipolar disorders, as the name suggests, occurs when people experience symptoms on both the depressive and manic side. This is the rule-of-thumb but doesn’t have to be the case as we’ll see in the specific diagnostic criteria in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5).

<a href=’https://www.freepik.com/photos/happy-sad’>Happy and sad photo created by dashu83 – www.freepik.com</a>

I mean…they are both mood disorders. Why be pedantic about it?

Bipolar disorders are often misdiagnosed as depression because the first episode the people experience is typically a depressive episode. Moreover, symptoms of mania may not be reported to physicians because people may not be aware that these symptoms are clinically important. In fact, studies have found that up to 40% of bipolar diagnoses are misdiagnosed as depression (Ghaemi et al., 1999).

But why is it important to differentiate between depressive and bipolar disorders? One important reason is treatment decision-making. Imagine someone goes to their physician for treating their depression. The physician naturally prescribes them antidepressants to treat their mood problems. However, this person actually has bipolar disorder. What might happen to somebody who has susceptibility to manic episodes when they take an antidepressant? As you might have guessed, this could increase risk of pushing them to the other side and inducing a manic episode (known as inducing mood-cycling). That’s why proper assessment and diagnosis is so important!

We’ll begin by discussing the symptoms of a major depressive episode and a (hypo)manic episode.

Criteria for a Major Depressive Episode (MDE)

MDE requires 5 of 9 symptoms for a period of at least two weeks, and the symptoms must be present most of the day, nearly every day. At least one of the symptoms must be: (1) depressed mood or (2) loss of interest in previously enjoyed activities.

– Depressed mood

– Loss of interest in previously enjoyed activities (anhedonia)

– Changes in appetite (or weight)

– Sleeping too much/sleeping too little

– Fatigue

– Feelings of guilt/worthlessness

– Feeling agitated or slowed

– Difficulty concentrating

– Suicidal thoughts

Criteria for a Manic Episode

Manic episodes require a distinct period of elevated or irritable mood that lasts at least one week, and is present most of the day, nearly every day. **Remember, this energy or irritability is significantly above what you experience on a day to day. For example, in irritability, you might find yourself getting into physical fights with strangers just because they looked at you wrong.

Besides elevated or irritable mood, you also need 3 of the following symptoms (4 if the mood is only irritable).

– Inflated self-esteem or grandiosity (“I’m the king of the world”)

– Decreased need for sleep (feeling rested after 3 hours, for example)

– More talkative than usual or pressure to talk

– Racing thoughts

– Distractibility

– Increase in goal-directed activity (e.g., taking on lots of projects) or psychomotor agitation (feeling agitated)

– Risky behaviours (buying sprees, lots of investments, driving well above the speed limit)

Differences between a manic and hypomanic episode

The symptoms are the same between manic and hypomanic episodes. However, there are a few ways to differentiate between a manic episode and a hypomanic episode.

– Duration. Hypomanic episodes are shorter than manic episodes. Manic episodes must last 7 or more days; hypomanic episodes only require 4 days.

– Impairment. Manic episodes are much more impairing than hypomanic episodes. In fact, people in hypomanic episodes typically do not report subjective distress. If hospitalization occurs (or there are psychotic features), it is a manic episode regardless of length of time.

– Observability. Manic episodes are typically much more excessive in their symptoms compared to hypomanic episodes. There needs to be an observable change to others in a hypomanic episode, but it is more subdued in comparison to manic episodes.

– Risky behaviours. Consistent with impairment, risky behaviours in manic episodes may be more severe compared to hypomanic episodes. For example, spending your entire life savings on a project may be more consistent with a manic episode compared to simply taking on more projects than you can handle.

Differences between Bipolar I, Bipolar II, and Major Depressive Disorder

To diagnosis Bipolar I, you only need a single lifetime manic episode. There is no need for any depressive episodes – if you have ever had a manic episode in your life, then this takes precedence over any hypomanic episodes or depressive episodes you have had. This is Bipolar I.

Bipolar II requires the presence of at least one hypomanic episode and one depressive episode in your life. The distressing part of Bipolar II is not the hypomanic episode; it’s the rapid cycling between different mood states. Somebody with Bipolar II will typically experience many episodes of depression and hypomania. This constant back-and-forth is often very distressing.

Finally, if you have no history of hypo(manic) episodes, and have met criteria for an major depressive episode, then the diagnosis would be Major Depressive Disorder.

Me calculating which depressive or bipolar disorder I might meet criteria for
Photo by Dan Cristian Pădureț on Unsplash

Treatment Options for Depression and Bipolar Disorders

In terms of medication, antidepressants (e.g., SSRIs, SNRIs, atypical antidepressants) are typically prescribed for depression. On the other hand, mood stabilizers (e.g., lithium) are recommended for bipolar disorders to avoid mood cycling. Below is more information on antidepressants and mood stabilizers.



Psychotherapy for depression include a number of different treatments: cognitive-behavioural therapy, interpersonal therapy, mindfulness-based therapies, acceptance and commitment-based therapies, among many others. There is less research on psychotherapies for bipolar disorders; however, one promising treatment is interpersonal and social rhythm therapy. This is based on the idea that irregular daily routines can lead to instability in our circadian rhythm. For people who are vulnerable to bipolar symptoms, this instability can promote mood episodes.

For people who are interested in evidence-based strategies for depression, here’s a few articles on thought records, mindfulness-based strategies, and behavioural activation!

Best wishes,