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The Science Behind Bipolar Disorder

Updated: Aug 23, 2022

What is bipolar disorder? How does the brain take part in this? Click here to learn more about bipolar disorder!


Figure 1: A visual representation of the symptoms of bipolar disorder


What is Bipolar Disorder?


Bipolar Disorder, or BD, is a mental disorder that causes significant mood swings which can affect energy levels, concentration, and activities during everyday life. This disorder can also cause “mood episodes” - periods of time where the person experiences extreme emotions such as happiness or depression.


When a person is experiencing extreme excitement, they tend to be very jumpy and full of energy. This is also called the mania episode. They might talk really fast and feel like their thoughts are racing and have no intention of getting much sleep.


On the other hand, when a person is experiencing extreme sadness, they tend to be very down. This is called the depressive episode as it seems like the person is in a state of severe depression. They might become worried, empty, or hopeless and have trouble concentrating and sleeping.


Sometimes, a person can experience both excitement and sadness in one episode. This is called a mixed episode.


Although, depending on the person, symptoms may not be as severe. They may feel different and unusual compared to how they normally feel and react in daily life, but it’s not too extreme either.


What happens in the Brain? - Neurotransmitters


Now we know what bipolar disorder is and what it may look like, we can focus on what might be happening in the brain during these episodes.


According to the experts, they say that bipolar is associated with certain small parts of the brain and can change the chemicals in those regions. This may also result in hallucinations and changes in thinking. This is because there is an imbalance of chemicals, called neurotransmitters. As it sounds in the name, neurotransmitters are chemicals that transmit signals from one nerve cell to another. In other words, neurotransmitters are like messengers. Depending on each person, this chemical imbalance can result in different symptoms as each person’s nerve cell reacts differently.


There are a huge range of different neurotransmitters that are affected due to this mental illness but the main three include dopamine, serotonin, and norepinephrine.


Dopamine is a chemical that makes people feel pleasure and happiness. In a person with bipolar, dopamine levels are very unstable. It’s a cycle where levels may be extremely high, which results in a mania episode, then become very low, which results in a depressive episode.


Serotonin is a chemical that helps with body functions such as sleep, mood, digestion, nausea, wound healing, etc. A person with bipolar may have more times when their serotonin levels are low. This can cause a depressive episode and low mood, resulting in low energy, suicidal thoughts, lack of interest, and so on.


Norepinephrine, also called noradrenaline, is a chemical that plays an important role in the “flight or fight” response. It increases heart rate and helps pump blood into the heart. People with bipolar may often experience times of low or high norepinephrine levels. This results in mania episodes (high norepinephrine levels) and depressive episodes (low norepinephrine levels). Some symptoms may include intense feelings of joy and happiness, hallucinations, impulsive choices, etc.


What happens to the brain? - Prefrontal Cortex, Gray Matter, and the Hippocampus


Experts also say that there could be changes in structure sizes in the brain. Some regions might be smaller than usual.


Some significant parts of the brain that are affected include the prefrontal cortex, gray matter, and the hippocampus. The prefrontal cortex is in charge of cognitive control, impulsivity, and attention. Gray matter is the outermost part of the brain and it is in charge of movement, emotions, and memory. The hippocampus also is an important part that controls emotions and memory.


In everyday life, gray matter helps us to control our movements, emotions, and memory. The more dense this part is, the better we can process. Although, with bipolar disorder, this region is no longer at its normal density. In fact, it is less dense, which means it is harder for the person to process and regulate their emotions and movement.


Bipolar also affects the size of the hippocampus. Normally, this part of the brain helps with emotional control, such as stress response, and the formation of memory. In people with bipolar, the hippocampus is smaller than usual, which explains why they may experience extreme episodes. In a 2017 study, researchers took MRI scans of 371 people. 133 had bipolar disorder, 152 did not have a mood disorder, and 86 had a major mood disorder different from bipolar. It was found that only people with bipolar had smaller hippocampuses compared to the other two groups.


Personal Opinion + Is there a Cure for bipolar disease?


Unfortunately, bipolar can create permanent brain damage and so far, there’s no cure. Hopefully, in the future, scientists are able to create a reliable solution and help save millions of people suffering from this mental illness.


*Disclaimer: For education purposes only. If you are concerned, please see a professional. This is not for diagnoses.*


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