How Does Bipolar Disorder Affect the Brain?

What Is Bipolar Disorder?

Bipolar disorder is a mood disorder characterized by cyclic episodes of severe depression and mania or hypomania. Bipolar disorder exists on a spectrum of bipolar I, bipolar II, cyclothymic disorder, and unspecified bipolar disorder. Those with the disorder may experience frequent mood swings, self-doubt, irritability, and other challenging symptoms.

Bipolar Brain Vs. Normal Brain

Bipolar disorder can affect the brain in many ways, possibly leading to brain damage. Many individuals with the disorder exhibit loss of gray matter and amygdala, hippocampus, or subcortical abnormalities. Chemical imbalances can result in various symptoms depending on the individual.

Bipolar disorder may affect the brain in the following ways:

Reduced Gray Matter

Gray matter forms the outermost area of the brain and is critical for processing information. Gray matter in regions responsible for mood regulation and movement differs in bipolar brains* versus normal brains. These dissimilarities may explain emotional regulation and arousal difficulties in those with bipolar.

One study shows a significantly lower volume of gray matter in the brains of people with bipolar disorder, most notably in the frontal and temporal regions.¹ More recent evidence suggests reduced gray matter more so affects those who experience frequent manic or hypomanic episodes.²

*The term “bipolar brain” is not fully agreed on in academics, but some research specifically uses this term. This article uses the term to accurately relay findings reported

Amygdala Functioning

The amygdala is a part of the limbic system partially responsible for processing fearful and threatening stimuli. When the amygdala is triggered, the fight or flight response is activated, alerting the body of perceived dangers.

Research claims that individuals with bipolar disorder exhibit over-activation in the amygdala.^3,4 This evidence suggests that those with the condition experience an impaired ability to respond accurately to environmental or social threats.

Decreased Size of Hippocampus

The hippocampus is another part of the limbic system perhaps altered in bipolar brains. This structure aids in memory formation and retrieval, emotional processing and control, and the release of the stress hormone cortisol.

Research using MRI scans shows that individuals with bipolar disorder are likely to have smaller hippocampi than those without mood disorders. This difference was particularly evident in participants with bipolar I and frequent manic episodes.⁵

Structural Connectivity

In one study, MRI scans of adolescents at high risk of bipolar showed decreased connectivity between brain areas involved in emotional processing over two years. Conversely, normal scans showed an increase in connectivity.^6,7

Neurotransmitter Fluctuations

Neurotransmitters carry chemical signals from one nerve cell to another nerve cell, muscle, or gland. Evidence shows that norepinephrine, serotonin, and dopamine levels are altered in bipolar brains, suggesting abnormal neurotransmitter regulation in people with bipolar disorder.⁸ It is impossible to determine what neurotransmitter causes bipolar disorder, but symptoms of bipolar disorder may develop when levels are imbalanced.

High levels of norepinephrine can cause manic symptoms such as:⁹

• Unusually high energy levels
• Intense feelings of happiness, euphoria, or joy
• Rapid speech
• Feeling agitated or easily annoyed
• Decreased need for sleep
• Becoming excessively involved in high-risk activities
• Racing thoughts
• Being easily distracted
• Impulsive behavior
• Psychotic experiences (hallucinations or delusions)

Low levels of serotonin can cause depressive symptoms such as:

• Low energy
• Lack of interest in activities usually enjoyed
• Feelings of guilt
• Self-doubt or self-critical thoughts
• Suicidal thoughts
• Feeling sad, hopeless, or irritable
• Loss of or excessive sleep
• Loss of appetite
• Poor concentration or attention
• Difficulty with memory
• Delusional thoughts

What Causes Bipolar Brain?

Various factors can cause bipolar-related physical and chemical abnormalities in the brain. It is unknown whether these brain changes and neurotransmitter imbalances cause bipolar or result from the condition.

Possible causes of bipolar disorder include:

• Genetics: Genetic differences exist between normal and bipolar brains. Research notes several genes associated with the development of the disorder. However, experts have not identified one undeniable genetic risk factor.¹⁰
• Childhood trauma: Childhood trauma or chronic adverse childhood experiences may be a causative factor of bipolar. Studies have shown an association between trauma during childhood and later diagnosis of bipolar with psychotic features.¹¹
• Stress: Different types of stress, acute or chronic, may trigger bipolar disorder in biologically predisposed populations.¹¹
• Lack of sleep: Lack of sleep may also play a role in bipolar disorder, and some research suggests that poor sleep may trigger manic episodes.¹²

Can Treatment Prevent Bipolar Brain Damage?

The abrupt and cycling moods seen in bipolar disorder can cause brain damage if left untreated or unmanaged. Many professionals primarily use medications to reduce lasting changes in brain functioning. There is no cure for bipolar brain, but bipolar treatment can help individuals cope with symptoms.

Medications

The most common medications for bipolar disorder include mood stabilizers, antipsychotics, antidepressants, and anti-anxiety prescriptions. MRI scans indicate that medication may have a protective effect on gray matter in bipolar brains. In one study, patients prescribed lithium showed less thinning of gray matter.¹³ Psychiatrists or physicians experienced with bipolar disorder can prescribe medications.

Common medications used to help manage symptoms of bipolar disorder include:¹⁴

• Mood stabilizers: Prescribers may recommend treating bipolar symptoms with Lithium or Depakote. Lithium affects serotonin and dopamine activity, while Depakote increases GABA levels to produce calming effects in the brain.
• Atypical antipsychotics: Abilify and Seroquel act by blocking chemical receptors in the brain, affecting serotonin and dopamine levels.
• Antidepressants: SSRIs* increase serotonin levels in the bloodstream. SNRIs* increase the levels of both serotonin and norepinephrine.
• Anti-anxiety medications: Short-acting and long-acting antianxiety medications treat anxiety symptoms, agitation, or insomnia. Anti-anxiety medications used in bipolar treatment may include Xanax, Ativan, Klonopin, and Librium.**

*This medication has a black box warning, the most serious kind of warning from the FDA for a risk of suicidal thoughts and behaviors in certain people. You should talk with your doctor about these risks before starting this medication.

**This medication has black box warnings, the most serious kind of warnings from the FDA for abuse or misuse, risk of physical dependence, and risk of serious side effects, including death, when combined with an opioid.

Therapy Options

Psychotherapy can also help prevent brain damage from bipolar disorder, particularly for individuals experiencing frequent manic episodes. In the early stages of stabilization, a therapist can help clients learn better symptom management. Treatment also focuses on adjusting to life without the characteristic highs of mania during depressive episodes. Finding the right therapist may take some time, but an online therapist directory allows you to narrow your search based on expertise, experience, and insurance coverage.

Common types of therapies used for treating bipolar disorder include:

• Cognitive behavioral therapy (CBT): CBT for bipolar disorder helps clients change negative thoughts that affect mood and behavior. CBT is associated with better treatment and medication compliance.
• Dialectical behavior therapy (DBT): DBT focuses on building new coping skills through mindfulness and increased distress tolerance. This approach helps clients manage depressive symptoms of bipolar and self-injuring behaviors.
• Electroconvulsive therapy (ECT): ECT sends electrical currents into the brain. ECT may help in cases of treatment-resistant bipolar disorder.
• Transcranial magnetic stimulation (TMS): TMS for bipolar disorder may relieve depressive symptoms by restoring functional neural pathways and chemical processes.¹⁵ However, TMS is not FDA-approved for treating bipolar disorder.
• Interpersonal and social rhythm therapy (IPSRT): IPSRT helps individuals discover which work, school, sleep, and recreational routines best assist in symptom management.

Final Thoughts

While some evidence indicates the existence of a ‘bipolar brain,’ there is no one cause of bipolar disorder. It is still uncertain if the abnormal brain structures and functions are either causes or results of the disorder. Further research can help determine the developmental and treatment roadmap of bipolar disorder. Early prevention offers the best chance for successful treatment and management.