What Is Bipolar Disorder?

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It was long believed that manic episodes straightforwardly caused structural and cognitive brain changes.

Evidence of these changes in never-symptomatic people with genetic risk for bipolar calls that into question.

Dementia risk is higher in people with bipolar but may be due to other factors like childhood trauma.

Certain lifestyle choices and treatments protect cognitive health, prevent episodes, and reduce dementia risk.

Cognitive dysfunction is a core trait of bipolar disorder. That's a short assertion bursting at the seams with nuance and caveat. For starters, what causes this core trait? The consensus had been that manic episodes progressively damage the brain, causing cognitive dysfunction, and eventually leading to dementia for some. Now we're not so sure.

In this post, we’ll follow a fictional composite named Josie whose story reflects what we see in research. She will help us sort out what’s known and reasonably hypothesized as of the late 2020s. Based on scans of her brain captured two years apart, we'll consider what she might expect as she gets older and what protective measures she might take.

Josie is a 25-year-old single mother and a participant in a longitudinal research study on cortical thickness changes in the brains of people with genetic risk for bipolar diagnosis. (Cortical thinning is one of several brain changes seen in bipolar disorder and is generally associated with cognitive impairment.)

Josie’s father had bipolar disorder, and while he was often supportive and loving, he also struggled with addiction and bouts of explosive anger. Genetically, she carries a baseline 5-10% risk of developing clinical bipolar disorder herself, and the trauma of her childhood may increase this risk.

Married at 20, Josie felt stable for the first time. She and her husband had two children before he was diagnosed with an aggressive terminal cancer. Widowed just before her 25th birthday, the young mother entered a new era of her life. Now a single parent, she works full-time, stresses frequently about money, and doesn’t get enough sleep.

Josie began the study and received her first scan at age 23. The second was about a year after her husband passed away. Here, we’ll need to make a small methodological leap to imagine that we have access to both Josie’s brain scans and her follow-up interview for analysis.

Cortical thickness in her first scan looks indistinguishable from that of the control group. In the second scan, however, we see excess thinning in frontal and temporal regions. And sure enough, the clinician’s notes indicate that Josie was hospitalized three months ago for her first manic episode.

So, what would you reason caused Josie’s cortical thinning? Two main frameworks have sought to answer this question.

Neuroprogression is a theoretical neurotoxic process of brain changes thought to be caused by repeated psychiatric episodes. When we consider that Josie’s cortices looked typical before onset and began to show thinning after her first episode, it would seem this event triggered the thinning.

Therefore, it would be crucial for her long-term brain health that she access treatment to prevent or minimize mania. Failure to do so could worsen cognitive decline and increase her risk of developing dementia.

Now consider Josie’s scans and diagnosis alongside the following two insights:

What Is Bipolar Disorder?

Take our Bipolar Disorder Test

Find a therapist to treat bipolar disorder

Many young people with genetic risk for bipolar start out with more cortical thickness than their peers with no genetic risk.

Among people with genetic risk for bipolar, the........

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