Obsessive-Compulsive Disorder and ADHD, at first glance, may seem like the polar opposite of each other. But in fact, they actually share a lot of the same wiring in our brains within the prefrontal cortex. Specifically the parts of our brains that control the ability to shift our attention, flexibility, habits, and goal oriented behaviors. These things affect behaviors such as how we make decisions, remember things, plan, and shifting focus from one thing to another.

Although both disorders affect the same neural pathways in the brain, they are in fact behaving in polarizing ways. It is because of this contradiction that some scientists still believe that the to conditions cannot co-exist. For example, how does a person act overly cautious and more inhibited, while at the same time act reckless and uninhibited. This is also backed up by brain scans of both conditions. People with OCD tend to have excessive prefrontal cortex activity (hypermetabolism), while people with ADHD tend to have decreased prefrontal cortex activity, (hypometabolism).