It turns out that bipolar disorder has a genetic link to at least four other mental illnesses: autism, attention deficit hyperactivity disorder (ADHD), major unipolar depression and schizophrenia. Since depression is part of bipolar disorder, it’s not surprising that unipolar depression might be related and any search for bipolar disorder is going to bring up schizophrenia. The others came as more of a surprise. The surprising thing is that there seems to be this same group of genes present in those of us with these mental illnesses that is responsible for these disorders and the one you end up with is dependent on how they express. Basically, roll the mental illness dice and see what comes up! Okay it’s not at all that simple, but when I first read about this, that’s what I felt like.
Let’s review. There are several potential causes of mental illness. We haven’t figured out exactly what does cause mental illness but the main theories currently involve genetics, brain structure, environment, and traumatic experience, among others.
- With genetics, it’s more likely that multiple family members will have mental illnesses.
- Imaging has shown that brain structures in those with mental illness do not function quite the same as those of the general population.
- Environment is, unfortunately, an incredibly broad category. It can stem from an uncontrollable, in-utero occurrence, to drug use or exposure later in life.
- Traumatic experience is fairly self-explanatory. It can be physical, social or psychological. An important thing to remember about trauma is that it is perceived trauma. If two people have the same experience, one may not experience the same level of trauma as the other. This doesn’t mean one person is stronger or better than the other. It’s just how the brain processes events at the time.
Back to genetics for a minute. If you have one of these psychological disorders in your genetic bloodline, you’re more likely to inherit a disorder, but it may not be the exact same disorder. It could be one of the other four. In fact, just because you have the gene doesn’t mean you will have a disorder at all! There has to be a stressor. Stressors go back to what I was talking about with environment and trauma. Basically, something has to happen in order for the gene to activate. There’s no real way to know, but I’m almost certain my stressor was the death of my grandfather. I’d had problems before that, but it really felt like everything went downhill from there.
It really isn’t just a role of the dice to see which of these disorders will present if the stressor is triggered. Pinning down the diagnosis is hard as it is. Most of the time, diagnosis for these disorders is a long process. They do have some overlapping symptoms, but they can be very few and more subtle. This link blurs the lines further.
Fortunately, (well, fortunately may not be a great word for anything related to this topic) there are correlations between the different illnesses and which ones may show up in other family members. Autism and ADHD are less likely to present than the others. However, ADHD is linked to childhood bipolar disorder. The earlier the onset of ADHD symptoms, the more severe the bipolar disorder. If bipolar disorder expresses in late childhood to adolescence, the severity of ADHD is lower.
The highest linked disorders are schizophrenia and bipolar disorder, meaning if someone in your family has schizophrenia you are more likely to develop bipolar disorder than major depressive disorder. If you have major depressive disorder, your children are more likely to develop ADHD than some of the others. Schizophrenia and autism spectrum disorder have the weakest link.
Research on this is still being done. Research on mental illness in general is huge. We just don’t know enough about the brain and how neuropsychology works. Findings like these genetic links are helpful. They are a step in the right direction, but we still have a long way to go.