Research is not at the point where we can link Bipolar disorder to one particular gene, or do one brain scan to see what's going on. The fact is that mental illness is much more complicated than other diseases that we can see, but that does not mean it doesn't exist. It means that because the brain is so amazingly complex, it takes a lot of research to target things like brain differences and genetic roots.
We do need this research, not to prove that bipolar exists, but in order to diagnose and treat people better. Which is why in two weeks my daughter and I are flying to the National Institutes of Health to participate in a research progam they are doing with kids with bipolar. We are doing this for better treatment for my daughter first of all, and then to advance the frontier of medical research. It is research that was needed yesterday.
There comes a point when you have ruled out every possible external cause, and you must look at the possibility of mental illness. Even though the research is not there yet, my child is. She doesn't look different, but she thinks and feels differently. And that is no less valid.
Here is some progress that's been made in research recently:
Genetic Roots of Bipolar Disorder
Bipolar Youth Show Distinct Pattern of Brain Development