Bipolar blogger Natasha Tracy offers exclusive insight into the world of bipolar disorder.See all posts »
Biological Evidence of Bipolar Disorder
Natasha Tracy vents her frustration with people who don't believe bipolar disorder is a real disease while offering evidence to the contrary.
One of the most frustrating things about my job as a mental health writer has to be dealing with the people that say that mental illness doesn’t exist. It’s dealing with the people who say that bipolar disorder doesn’t exist because there is no definitive biological test and therefore does not need treatment. It’s dealing with the people who say that as mental illness is “all in your head,” it isn’t real, and psychiatry is a sham.
I fear these people will cause me a very real aneurysm.
So today we look at some of the neurobiological evidence for bipolar disorder. So that I, and you, can answer these people with a few facts.
Bipolar Disorder Etiology (Causes)
No one knows, specifically, what combination of factors causes any single case of bipolar disorder but it is clear that genetic, biochemical, psychodynamic, and environmental factors play a role. But no single factor can cause bipolar disorder. We simply know of many factors that increase your risk, not specifically the ones that will absolutely cause it. This is similar to our understanding of cancer.
Biological Markers of Bipolar Disorder
The Holy Grail in bipolar disorder diagnosis would be a biological marker that we could test for that would definitely indicate the presence or the absence of bipolar disorder. For example, a brain scan that would point to the illness.
Unfortunately we don’t have that, yet. But we’re steadily moving in that direction.
There are some things we’re getting clear on. Research has shown the following:
- Myelin, a sheath that covers a neuron projection, increases conduction of nerve impulses in the brain. A loss of myelin is thought to lead to disrupted communication in the brain and thought disturbances such as those seen in bipolar disorder. Brain imaging and postmortem studies show that people with bipolar disorder have abnormal and decreased myelin is several areas of the brain.
- A decrease in gray matter mass is seen in various part of the brain, and in some cases, areas that regulate emotion, in those with bipolar disorder.
- Cell loss and atrophy is also apparent in some areas of the brain in those with bipolar disorder. Some of the medications that treat bipolar disorder are known to increase factors that protect neurons (neuroplasticity and cellular resiliency) and fight this effect.
- Some types of interneurons have been found to be reduced in the hippocampus of people with bipolar disorder.
(It’s worth noting that many of the above brain alterations are seen in similar forms in the brains of people with schizophrenia suggesting a strong link between the two disorders.)
However, while all of the above are brain changes that have been shown to appear in bipolar disorder, none of these can definitely be used for diagnosis.
Part two of this series will focus on the genetics of bipolar disorder.
Please see here for more information on the neurobiology of bipolar disorder.