The relationship between bipolar and schizophrenia is a fraught one. Are they part of a larger spectrum? The word is still out. Are they the same genetically? They definitely share similarities. Are the symptoms the same? There are similar behaviors, but distinct differences. So what do we do? How much weight do we give these differences? Should patients even worry about it? Well, I’m not a doctor, and I don’t have all the answers. What I do know is that there is emerging evidence linking bipolar disorder and schizophrenia and it involves a part of the brain not often acknowledged.
Brain research on mental illness often focuses on the frontal lobe. The frontal lobe is largely responsible for “higher mental processes”. These include decision making/problem solving, memory, and personality. You can see why this type of research is important. As patients, we have the burden of being at the mercy of these functions, or rather their dysfunctions. While most people get to go through the day with fully reliable frontal lobes, ours determine whether or not we can even function that day.
However, there is evidence out that we may need to pay more attention to another part of the brain- the cerebellum. It’s located at the back of the brain and is largely responsible for autonomic motor skills. This is how you can walk and talk at the same time. Your cerebellum is taking care of the walking so you don’t have to think about it. Still remember how to ride a bike? Thank your cerebellum. Because of its apparently basic function, it’s not given the star-power status that the frontal lobe gets. Think about it, fish have cerebellums, but not frontal lobes. However, research may be making some shifts.
If you were damage your cerebellum, you would likely end up with peripheral nervous system damage. This results in symptoms like motor dysfunction, clumsiness, loss of physical sensation, headaches and a lot more problems related to your body movement and control. I advise you not to damage your cerebellum.
Then there’s the damage that can happen without noticeable injury. In fact, it occurs with bipolar disorder and schizophrenia, and it’s likely genetic. The size of the cerebellum is smaller in both bipolar and schizophrenia, which is part of the problem. The damage to the cerebellum is subtle, but significant. Consider it “poor mental coordination.” It’s also referred to as neurological soft signs. It can have similar symptoms to run-of-the-mill damage, and it often does. There are other signs that were tested including gait, touching finger to nose, and clarity of speech. (Insert comment about field sobriety tests here.)
An important note with these symptoms showing up in bipolar disorder and schizophrenia is that they show up when patients are in remission or euthymic. So, if I’m in the middle of a depressive episode and having motor problems, those problems are not going away when the depressive episode ends.
So at this point, it seems like there could be another link between bipolar disorder and schizophrenia since there is not a significant difference between the illnesses as far as physical brain abnormalities and neurological soft signs.
There is good news at this point though. Well, I guess “good” depends on your perspective. Treatment can also be geared towards these symptoms and may be able to help overall, as atypical antipsychotics do not improve the motor function symptoms long-term. Additionally, the worse the neurological soft signs, the less likely the patient is to respond to the most common treatments, which could help speed up the treatment process.
And, really, who doesn’t want to make the treatment process more efficient?