Mental illness is not a single entity located in just one area of the brain. Rather, there are different types of mental illnesses and each appears be affected by changes in its own specific brain region. To a degree this has been known for years. What is new is that researchers in Australia have mapped these changes in one thousand three hundred people with various mental health conditions. The study looked at volume of more than a thousand different regions of the brain. They found strong correlations between mental illness and changes in the brain.
Mental Illness Types Versus Brain Region Volume Study
The study in Australia included people with attention-deficit hyperactivity disorder, autism spectrum disorder, bipolar disorder, depression, obsessive-compulsive disorder, and schizophrenia. They found individual brain changes that matched specific mental illness diagnoses. They began with standard measurements of various brain regions for the general population and then compared measurements of patients with specific mental illnesses.
Mental Illness and Brain Area Volume Study Results
What the researchers found was that within a given diagnostic group for mental illness no more than seven percent of people fell outside of the expected size range of a given brain region for that group. They say that this tells us that using brain volume by brain region as a diagnostic tools would be inaccurate. However, it also shows us how individuals with the same mental illness have similar physical changes in their brains. It also helps explain why within a mental illness groups there is variation in illness presentation and treatment outcomes.
Brain Connectivity and Mental Illness
Something that we have written about is how psychedelic medicines increase brain connectivity at the same time that they improve conditions like PTSD and depression. The point being that brain connectivity relates to mental illness in many cases. What the researchers found was that specific connectivity issues between different segments of the brain were common within individual mental illness groups. As an example, they discovered that circuits connecting to frontal areas of the brain were commonly affected in patients with depression. Like with the brain volume work, there was enough variability within and between groups that the findings would not be useful for diagnosis of mental illness. Nevertheless, their finding help show us the nature of brain areas and interconnections within and between mental illness groups.
Brain Use and Shrinkage or Growth
It may an overused comparison but it holds some truth that the brain is like a muscle. Use it and it stays healthy and even grows. Do not use it and it shrinks and gets weaker. There is strong evidence that the amygdala or fear processing center of the brain enlarges and develops more connections in conditions like PTSD. Some mental illness result in people increasing the use of some areas of their brain while neglecting others. Continuation of this sort of brain use and non-use can lead to the kinds brain volume and brain connectivity changes seen in the Australian study. It gets to the point where a mental health condition affects how the brain is used and then the resulting state of the brain affects the mental illness. The point is that studying that brain in various mental illness states helps us understands the physical basis of these mental illness and can lead to improvements in treatments.
What Do Medicines for Mental Illness Do to the Brain?
Going back to the use of psychedelics for depression or PTSD, the effects of psychedelics on brain connectivity appear to be important in achieving the desire treatment result. When a person is treated for depression the treatment end point is generally when they are no longer depressed. Perhaps with the sort of research being done in Australia we will find out that the treatment endpoint should be when the volume or connectivity of a specific brain region increases by a measurable amount! Because we are concerned about how depression, PTSD, and other conditions are risk factors for suicide, it will be useful to know which treatment end points will be most effective over time in not just treating the primary disease but also preventing suicide as an outcome. The work they are doing in Australia is in its early stages but could help in the long term with this issue.