Bipolar Spectrum Disorders (BSD): Types Of Bipolar Disorder And Treatments
Bipolar spectrum disorders (BSD) is the name given to a group of conditions made up of three types of bipolar disorder, as described by the World Health Organisation (WHO) in this 11 country 4 continent study of just over 61,000 people.
There are three main types of bipolar disorder:
- Bipolar disorder type I, the classic form
- Bipolar disorder type II
- Subthreshold bipolar disorder (also known as Bipolar Disorder Not Otherwise Specified (BD-NOS) or unspecified bipolar disorder) which accounts for a large proportion of those diagnosed with major depression. For example, one key study found that up to 40% of people with major depression suffered subthreshold bipolarity. Another large study of 43,000 people found that subthreshold hypomania is in more than 70% of pure clinical trial level major depressive disorder.
There are also other subtypes which have organic causes such as brain injuries, tumour, medication or substance use disorders. These subtypes require treatment of the organic cause rather than the bipolar disorder itself. Rapid cycling is a pattern (4 or more distinct mood episodes over a year) that can occur in all types of bipolar disorder.
Here, we will confine our explanation to the three main types of bipolar disorder: Type I, type II, and subthreshold.
A landmark World Health Organisation (WHO) study showed that the disability burden of bipolar disorder in general is greater than all forms of cancer, epilepsy and all known neurological diseases including Alzheimer’s disease.
Bipolar Disorder Type I
Bipolar disorder type I is more commonly known as ‘manic depression’. As a result, it is often assumed that manic depression is in fact the whole of bipolar disorder, but the reality is very different.
The above WHO study found that 0.6% of the population across the world (11 countries in 4 continents), including 1% of Americans suffer from bipolar type I. That constitutes 25% of all bipolar spectrum disorders.
In theory, bipolar disorder type I is the most severe form of bipolar disorder, at least for the elevated mood part, wherein people experience mania for at least 7 days. Mania in which a person’s functioning deteriorates substantially is a prerequisite for a diagnosis of bipolar type I. Periods of depression also occur and last 2 weeks or longer.
Bipolar Disorder Type II
Bipolar type II is a condition where patients experience four days of uninterrupted mild elevation of mood called ‘hypomania’. With hypomania, sufferers can maintain their functioning. If their functioning is disrupted then this is classed as mania.
If mania lasts seven days or more, then it is considered to be bipolar disorder type I or ‘manic depression’. The depressive phases of type II are no different in severity and role impairment to those in bipolar disorder type I. This WHO study found that the disability and severity of symptoms of depression bipolar I and II and subthreshold bipolar disorder is similar.
The same WHO paper found that 0.4% of the world population and 1.1% of the U.S. population is estimated to suffer from bipolar type II. This makes up 16.6% of all bipolar disorders. Typically the condition is plagued with failure of diagnosis. This is often because clinicians fail to ask about periods of hypomania and patients do not feel that they are impaired during these phases (because they are still functioning) and so forget to mention them.
Subthreshold Bipolar Disorder
of the worldwide population has subthreshold bipolar disorder
of the U.S. population has subthreshold bipolar disorder
Subthreshold disorders make up the majority of bipolar disorders. In the US, subthreshold is known as ‘BD-NOS’ (Bipolar Disorder Not Otherwise Specified). In ICD-10, the WHO manual, it is known as ‘unspecified bipolar disorder’.
Subthreshold bipolar disorders are characterised by manic symptoms in the presence of depression. Examples of these include: flight of ideas, racing thoughts, agitation, impulsivity, irritability or high libido in the presence of depression.
In the depressive phases, subthreshold bipolar disorders are equally disabling and as severe as bipolar type I and II.
Other forms of subthreshold bipolar disorder include periods of mania for less than 7 days and periods of hypomania for less than 4 days. In ICD-11, the WHO manual, uninterrupted depressive phases of less than 2 weeks would be classed as subthreshold.
What plagues this condition is what is known as rapid cycling, whereby people can experience 4 or more mood changes in a year. Rapid cycling is a pattern of bipolar activity. It can occur in all forms of bipolar disorder and makes the condition treatment-resistant. Sometimes the presentation is of several moods in a day or multiple mood changes over a week or so. We call this ‘change of polarity’. The problem for clinicians has been that there are no distinct episodes of 7 days of mania, 4 days of hypomania and 2 weeks of depression, as described in bipolar I and II. This means, if clinicians follow the NICE guidelines, subthreshold bipolar disorder falls off their radar and gets diagnosed as depression or Treatment-Resistant Depression (TRD). Read more about rapid cycling.
In the NICE guidelines bipolar disorder is described as 7 days of mania or 4 days of hypomania. It fails to include people who may experience (for example) 3 days of mania or 2 days of hypomania. Do they not count as bipolar patients?
Those who don’t fall into the 7 days of mania (of bipolar type I) or 4 days of hypomania (in bipolar type II), i.e. those with subthreshold bipolar disorder, actually make up around 55-60% of all people with bipolar disorders.
The National Institute for Health and Care Excellence (NICE) provides guidance, advice, quality standards and information services for health, public health and social care. Unfortunately current (NICE) guidelines on bipolar only make recommendations for assessment and treatment of bipolar disorder type I and II, excluding subthreshold bipolar disorder. The NICE draft for consultation agrees that there is a concept known as bipolar spectrum, yet makes clear that the guidelines only refer to bipolar type I and II. And in spite of the fact that subthreshold bipolar sufferers are actually the majority.
Given the impact on quality of life that subthreshold bipolar disorder has, and the fact that it fails to respond to the standard treatment, this condition needs much more awareness, training and recognition in the UK.
NICE does not make any recommendations for the assessment and management of subthreshold bipolar disorder as a condition (see page 21, lines 9-12), meaning there is presently no recommended treatment for 55-60% of all bipolar disorders.
Indeed, in the United Kingdom, sadly, clinicians are not trained to look for signs of subthreshold bipolar disorder or treat it. The result is that these patients are usually misdiagnosed with depression and are treated with a combination of Cognitive Behavioural Therapy (CBT) and antidepressants.
In fact, 40% and and 70% of people with “major depression” have subthreshold bipolar disorder and can be directly harmed by treatment with antidepressants. They tend to be diagnosed with treatment-resistant depression (TRD) and prescribed many drugs which can make the condition worse in the long run.
So if you have been diagnosed with depression or TRD, have tried multiple antidepressants but have not improved, or have gotten worse, it may be time to consider whether you could have a bipolar spectrum disorder.