Impact of bipolar disorder on the neurobiological structure
Mental health condition known as bipolar disorder can lead to extreme fluctuations in emotions. This disorder is linked to alterations in both the brain's structure and function.
Individuals with bipolar disorder may experience swift transitions between feeling down and going through manic episodes. This disorder can impact focus, energy levels, and decision-making skills.
Historically, bipolar disorder has been referred to as manic-depressive illness or manic depression. The high moods or euphoria, and low moods or depression can persist for extended periods, often weeks or longer.
This article explores the variations between the brains of individuals with bipolar disorder and those without this condition. It also provides answers to common questions regarding bipolar disorder.
Bipolar disorder and the brain
Bipolar disorder affects various brain structures and its overall functioning.
Researchers believe that changes in brain chemicals and possible reductions in certain brain regions contribute to bipolar disorder. It may also trigger hallucinations in some cases.
The connection between brain changes and bipolar disorder is not entirely clear. Some studies suggest that alterations to the brain could result from the disorder, while others propose that the disorder is caused by these brain changes.
What occurs in the brain of someone with bipolar disorder?
The brain of an individual with bipolar disorder can differ significantly from the brain of an individual without the disorder.
A chemical imbalance in neurotransmitters, which are brain chemicals that help communicate between brain areas, could contribute to bipolar disorder. High levels of certain neurotransmitters may cause manic episodes, while low levels may result in depressive episodes.
Additional structural changes in the brain, such as a reduction in size in certain brain regions, have also been linked to bipolar disorder.
Selected brain areas impacted by bipolar disorder
Bipolar disorder affects all parts of the brain, both structurally and functionally.
Notable brain regions impacted by bipolar disorder include:
- The prefrontal cortex: This part of the brain plays an essential role in mood disorders, cognitive control, impulsivity, and attention.
- Gray matter: This is the outermost layer of the brain. Gray matter is responsible for information processing, movements, emotions, and memory.
- The hippocampus: This brain region is involved in emotions and memory.
Bipolar disorder may reduce gray matter volume
Gray matter plays an important role in enabling humans to carry out daily activities. Found in both the central nervous system (CNS) and the brain, gray matter contributes in some way to human life.
A study found significantly lower gray matter volume in the brains of individuals with bipolar disorder compared to individuals without the condition. This reduction was also observed in individuals with major depressive disorder.
These reductions in gray matter occurred in regions associated with mood regulation, information processing, and body awareness.
In a 2021 study, researchers did not find any consistent differences in brain volume between individuals with and without bipolar disorder. However, they did report a relationship between a higher frequency of manic and hypomanic episodes and gray matter loss, primarily in the prefrontal cortex.
Bipolar disorder may shrink parts of the hippocampus
The hippocampus is an essential brain area for controlling emotions, including the stress response, and memory formation and retrieval.
In individuals with bipolar disorder, parts of the hippocampus may be smaller than in individuals without a mood disorder, although research findings have not always been consistent.
A study investigated whether hippocampal volume was related to mood disorders and mood episodes. The researchers used MRI scans to examine the brains of study participants and measure the volumes of various brain regions.
The study included 152 individuals without a mood disorder, 133 with bipolar disorder, and 86 with major depressive disorder.
The researchers compared the MRI scans and found that specific portions of the hippocampus were smaller in individuals with bipolar disorder than in those in the other two groups.
The size reductions in hippocampal regions were most noticeable in individuals with bipolar I disorder, which often involves phases of extreme mania. In fact, the reduced hippocampal volume was most significant in individuals who had experienced the most manic episodes.
More recently, a study also concluded that reduced hippocampal gray matter volume is a common feature in individuals with bipolar disorder.
Bipolar disorder may alter the brain’s chemical balance
Researchers believe that bipolar disorder is associated with a chemical imbalance in the brain.
Brain chemicals called neurotransmitters help transmit messages between different regions of the brain. A potential imbalance of these chemicals could be responsible for symptoms in bipolar disorder.
However, it is not yet clear whether this imbalance causes bipolar disorder or occurs due to it.
Key neurotransmitters affected by bipolar disorder
The three main neurotransmitters that may be impacted by bipolar disorder are:
- Dopamine
- Serotonin
- Norepinephrine
Symptoms of high norepinephrine levels
In individuals with bipolar disorder, high and low levels of norepinephrine (also known as noradrenaline) are associated with periods of mania and depressive episodes, respectively.
During a manic episode, an individual with bipolar disorder may experience:
- high energy
- intense happiness, elation, or joy
- new ideas or plans
- rapid speech
- feeling quickly agitated or annoyed
- hallucinations
- delusions or illogical thinking
- trouble focusing
- impulsive decisions, such as overspending
- lack of appetite
Symptoms of low serotonin levels
Low serotonin levels are associated with depressive episodes and low mood.
Individuals with bipolar disorder experiencing a depressive episode may experience:
- loss of energy
- feelings of despair or hopelessness
- changes in appetite or sleep patterns
- trouble focusing
- loss of interest in activities
- feelings of worthlessness or guilt
- suicidal thoughts or actions
- irritability or agitation
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- Low vitality
- Considerations of self-harm
- Often feeling down, hopeless, or impatient
- Self-doubt
- Decreased enthusiasm
- Feelings of remorse
- Pessimistic outlook
- Trouble sleeping
- Diminished appetite
- Difficulty focusing
- Memory lapses
- Delusional ideas
Frequently Asked Questions
Below, we address some common queries regarding bipolar disorder.
Does bipolar disorder impact the brain negatively?
While it's still unclear if alterations in the brain lead to bipolar disorder or are triggered by it.
Can the brain recover from bipolar disorder?
There is no cure for bipolar disorder, and certain brain changes can be lasting.
Using medications like lithium, however, may have a "balancing" impact on the brain, according to a researcher's work published in a journal. This individual concluded that utilizing lithium or mood stabilizers is linked with an increase in gray matter volume.
Does bipolar disorder worsen with age?
Every individual with bipolar disorder is unique, and they may experience differing symptoms as they age.
The Depression and Bipolar Support Alliance suggests that episodes of depression and mania might decline with age. It notes that mania may decrease more than depression.
However, this isn't the case for everyone, and mania or depression may intensify with age for specific individuals.
Can someone with bipolar disorder ever feel ‘normal’?
Between episodes of depression and mania, a person with bipolar might undergo periods of regular mood. With appropriate treatment, the severity and frequency of such episodes may also lower, enabling them to lead as ordinary a life as possible.
Individuals with bipolar disorder may experience drastic shifts between periods of intense happiness or mania and deep feelings of sadness or depression. The disorder can affect various brain structures and their functions, potentially leading to alterations in brain chemicals and reductions in certain brain regions. High levels of neurotransmitters like norepinephrine during manic episodes and low levels during depressive episodes are associated with bipolar disorder symptoms. Researchers are still investigating the relationship between brain changes and bipolar disorder, with some suggesting that changes in the brain result from the disorder and others proposing that the disorder is caused by these changes.
