What is the difference between Bipolar Disorder and Bipolar Depression?
Bipolar disorder is a mental condition characterized by episodes of mania and depression. Bipolar depression refers specifically to the depressive phase of bipolar disorder.
What is Bipolar Disorder?
Bipolar disorder is a debilitating mood disorder characterized by phases of mania and hypomania [1]. This means that a patient with bipolar disorder alternates between manic episodes of feeling "on top of the world" and depressive episodes where "every day is a struggle".
Bipolar disorder first appeared in the Diagnostic and Statistical Manual of Mental Health (DSM) in its 3rd edition in 2005, making it a newly recognized disorder [2]. Currently, bipolar disorder has a higher rate of suicide than severe major depression and a higher rate of hospitalization than moderate major depression [3]
What is Bipolar Depression?
Bipolar depression is one of the core symptoms of bipolar disorder. Bipolar depression refers to the periods of low mood, fatigue, apathy and low motivation to engage in daily activities that individuals with bipolar disorder experience [1].
Bipolar depression is a symptom of bipolar disorder that is difficult for patients to recognize, as they may not have a perspective on their daily experiences of low mood and fatigue [4]. This is why the diagnosis of bipolar disorder is often assigned 6-8 years after symptoms have first appeared [5].
Bipolar depression is the most significant morbidity, meaning the greatest detriment to patient well-being and quality of life. Studies suggest that up to 40% of bipolar disorder patients experience long-term unemployment at some point in their adult life, most of which is attributed to depressive episodes [6].
Bipolar I vs Bipolar II
In the ICD-11, bipolar disorder has been separated into bipolar I and bipolar II, referring to the two most frequent presentations of bipolar disorder [1, 7].
- Bipolar I is a subtype of bipolar disorder in which individuals more commonly experience mania, meaning the 'on top of the world' feeling.
- Bipolar II is a subtype of bipolar disorder in which individuals more commonly experience depression
Interestingly, the percentage of time patients in both bipolar I and bipolar II spend in the depressed state is still higher than either group spends in the manic state (36% vs 37% for depression and 11.5% vs 9.8% for hypomania, respectively) [8].
Other than bipolar I and II, the group of bipolar disorders, according to the ICD-11, also includes cyclothymic disorder (cyclothymia) and other unspecified bipolar and related disorders [1, 7].
Treatments for Bipolar Disorder
Bipolar disorder treatment is a substantial unresolved challenge, demonstrated by high suicidality, poor diagnosis, and low patient adherence to the treatment [4]. Various treatment methods exist, ranging from less common ones, such as ketamine for bipolar disorder, to more common ones.
Common treatments include:
Lithium for Bipolar Disorder and Bipolar Depression
Lithium is highly effective at reducing suicidality and has been the #1 treatment for bipolar disorder and bipolar depression since the 1950s [9]. The way lithium works is still intensely studied. Still, it likely involves effects on neuroprotective and neurotrophic factors, meaning processes that protect the brain and help it grow and re-wire in beneficial ways [10]. Through these yet-to-be-clarified mechanisms, lithium helps approximately 60% of patients achieve remission [4].
Lithium has several side effects, including weight gain, gastrointestinal issues, a metallic taste in the mouth or slight tremors [11]. It is also easy to overdose on lithium, making lithium prescriptions for bipolar disorder and bipolar depression tightly controlled [10, 12].
A curiosity about lithium is that it cannot be patented by pharmaceutical companies, leading to declining trends in lithium prescriptions for bipolar disorder and bipolar depression in the United States but not in the United Kingdom [13].
Antidepressans for Bipolar Disorder and Bipolar Depression
At first glance, antidepressants appear to be an excellent treatment for bipolar depression. They have, after all, been used to treat bipolar depression, whether alone or in combination with other drugs, for decades [4].
The essential detail is that bipolar depression rarely occurs without concomitant manic phases, which can be exacerbated by antidepressants. There is a paucity of promising clinical trials that would support the use of antidepressants for bipolar disorder or bipolar depression, leading to the recommendation that antidepressant therapy alone is not an effective treatment for bipolar disorder, especially for bipolar I [12]. For bipolar II, antidepressants may be well tolerated, and experimental trials are helping to identify specific patients who would benefit from taking antidepressants [14].
Anticonvulsants for Bipolar Disorder and Bipolar Depression
Anticonvulsants are a type of drug that reduces the excitation within the brain, typically used for seizures [15]. A systematic review from 2013 found that two specific anticonvulsants were efficacious and well-tolerated in bipolar disorder [16]. A more recent study indicated valproate as effective at managing manic phases of bipolar disorder but with little effect on bipolar depression [17].
Therefore, anticonvulsant medication can help treat bipolar disorder I, but not bipolar depression. For bipolar I patients, anticonvulsants are deemed safer and, therefore, better than lithium to stabilize manic episodes [17].
Antipsychotics for Bipolar Disorder and Bipolar Depression
Antipsychotics are drugs that reduce the activity of the dopamine system. In bipolar disorder, olanzapine, a second-generation antipsychotic, is commonly prescribed with fluoxetine, an SSRI as an effective combination treatment, superior to just using the antipsychotic medication [18].
Examples of other antipsychotic medications that can be used to stabilize mood in bipolar disorder include cariprazine, lurasidone, and quetiapine [4]. Antipsychotics must be only used in the short term, as they have an adverse impact on weight and blood pressure, increase restlessness, and exacerbate fatigue [19].
Electroconvulsive therapy for Bipolar Disorder and Bipolar Depression
Electroconvulsive therapy, or ECT, is an invasive treatment that administers an electric shock to the patient, which induces a seizure in the brain. A seizure refers to a large-scale increase in excitatory activity throughout the brain, which can have therapeutic benefits on neural pathways of bipolar disorder [20]. ECT has traditionally been used in major depression but has shown benefit in a large proportion (60%) of patients with bipolar disorder [21, 22]. The number of patients that recovered using ECT was comparable across bipolar I and bipolar II, indicating ECT is equally effective for bipolar depression as it is for mania.
Psychosocial Interventions for Bipolar Disorder and Bipolar Depression
Psychosocial interventions for bipolar disorder and bipolar depression include individual talking therapies, group therapies or dance/art therapies, among others. These have shown substantial improvements in the long-term management of bipolar disorder, especially when combined with medication [4].
A recent comparison study of different therapeutic approaches found that the popular Cognitive Behavioural Therapy and Mindfulness-based cognitive therapy were the most beneficial in preventing relapse in patients with bipolar disorder [23]. The study also highlighted the positive impact of psychoeducation and lifestyle adjustments, such as regular sleep patterns, coping with stress and healthy eating.
Is Bipolar Depression Treated Differently Than Bipolar Disorder?
As summarized above, there is a spectrum of treatment methods for bipolar disorder vs bipolar depression. However, what treatments are generalizable to all patients with bipolar disorder vs the treatments explicitly designed for bipolar depression?
- Antidepressants and ECT are treatments that predominantly address bipolar depression.
- Lithium, antipsychotics, and anticonvulsants are generally more efficacious at managing manic episodes and less beneficial for reducing symptoms of depression, such as bipolar depression.
To summarise, bipolar disorder is a debilitating mental illness with fluctuations between mania and depression. Bipolar depression is the specific symptom of bipolar disorder that refers to depressive episodes. The prevalence of bipolar depression differs between bipolar I and bipolar II, which also influences the types of treatment used for bipolar disorder vs bipolar depression.
As bipolar disorder is a severe psychiatric illness, all symptoms and medication must be consulted with your medical provider or psychiatrist.
