Differentiating Bipolar Disorder from unipolar depression

Features of bipolar depression

As already mentioned, picking up on bipolarity can sometimes be difficult as patients are more likely to present when experiencing a bipolar depression than when they have a 'high'. (This is depression in someone who has Bipolar Disorder and has therefore experienced either a manic or hypomanic episode in the past). Patients with Bipolar Disorder can also experience mixed episodes (during which time they experience a mixture of both manic and depressive symptoms). Mixed episodes can risk being confusing to the clinician not familiar with Bipolar Disorder. (Another term for this state is 'dysphoric mania').

A number of commentators (particularly in North America) have attempted to define the key features of Bipolar Disorder and ones that can be distinguished from unipolar depression. However, we believe that the logic of comparing one heterogenous group with another heterogenous group (i.e. 'bipolar depression' with 'unipolar depression') is very limited. The great majority of people with unipolar depression have non-melancholic depression while the great majority of those with Bipolar Disorder have melancholic or psychotic depression. Therefore, there will be more biological features in those with Bipolar depression as the probability of the melancholic and psychotic sub-types is increased.

The commonly described features of bipolar depression (both in those with Bipolar I and II) - and that distinguish it from non-melancholic depression - therefore tend to be the melancholic or psychotic features.

Download Clinician sheet on Non-Melancholic Depression [PDF, 79KB]
Download Clinician sheet on Melancholic Depression [PDF, 92KB]
Download Clinician sheet on Psychotic Depression [PDF, 43KB]

Melancholic features

The core feature of melancholia is psychomotor disturbance: either psychomotor retardation or agitation. Psychomotor retardation can fluctuate during the day, but is often worse first thing in the morning. This is another reason why repeated assessments can be useful. If there seems to be a discrepancy between what a patient is describing and how they appear in the interview, then scheduling appointments first thing in the morning may be helpful.

Psychomotor retardation

Having a profound lack of energy, an inability to 'fire up'. (Getting out of bed in the morning or having a shower can seem like monumental tasks; people can stay sitting in the same position, doing nothing, and/or thinking nothing for hours on end.)
Feeling physically and mentally slowed (the thought process is often described in terms like 'thinking through a fog').
The person moves and talks slowly. They show a lack of facial expression and a lack of reactivity when being interviewed. They can take a long time to respond to questions (which can sometimes be frustrating to a time-pressed clinician).
During interview the person shows poor concentration and inattention.

Psychomotor agitation

Feeling intense physical agitation that is easily observed by others. This is often seen as inability to sit down, with pacing and hand-wringing. It is often accompanied by repeated expressions of distress i.e. 'what will become of me?'

Other features of melancholic depression

These include:

Anhedonia - inability to experience pleasure, a loss of anticipatory pleasure.
Non-reactive mood - patients often describe themselves as feeling 'low', 'empty', 'numb' or 'flat' as well as depressed.
Mood and lack of energy is worse in the morning

Other features of melancholic depression - the type of depression suffered by people with Bipolar Disorder - are often seen in what has been called in the past as 'atypical depression'. These include:

Changes to appetite - being likely to eat more rather than less, with associated weight gain rather than weight loss.
Changes to sleep - more likely to sleep in and longer (i.e. hypersomnia) than show the classic early morning waking pattern, although there may be an age influence, with early morning wakening replacing hypersomnia in older patients.

Useful questions to ask to elicit these symptoms:

Is it hard for you to 'fire up' - get out of bed and have a bath?
Do you still read the newspaper ... watch TV?
What do you do all day ... what would you normally be doing?
What do you still enjoy ... hobbies, children/grandchildren, sunrise?
Dyou feel worse in the morning or evening?
How do you sleep? Do you wake early in the morning?
Can you be cheered up? What lifts your mood?
Are your concentration and short-term memory impaired?

It can sometimes be useful to get patients (or partners or family members) to read about melancholic depression to see if they identify with the symptoms described.

Features of psychotic depression

The features of psychotic depression include profound psychomotor disturbance, similar to, but at the severe end of what is seen in melancholic depression. Cognitive functioning is impaired; this can range from mild cognitive processing problems through to a Pseudo-dementia picture. The person also experiences psychotic symptoms, commonly delusions (90%) and sometimes, but less commonly hallucinations (10%). The types of delusions are characteristically (but not always) 'mood congruent' with pathological guilt being a main underlying main feature. People can also develop delusional beliefs about the functioning of their bodies (e.g. believe that they have a terminal cancer or that their bodies are rotting inside). Other types of beliefs are persecutory delusions (i.e. that people, known or unknown, are trying to harm them). In such severe states, Electroconvulsive therapy may be recommended in order to bring about a more rapid reduction in delusional symptoms.

Useful questions to ask to elicit these symptoms

Are you a good person? or, do you feel guilty? ... or, do you feel that you deserve to feel like this?
Are you being punished ... or feel that you are being punished for something you have done?
Are you being watched or poisoned?
Do you have voices in your head telling you that you are bad ... or, deserve to be punished? or that you should kill yourself?
Do you think that you have something physically wrong with you? What are your concerns? What evidence do you have?
Are you thinking about minor indiscretions of the past (e.g. not declaring all your income tax) that you wouldn't generally even think about?