The Bipolar Brain

When you have a heart attack, people can locate where the plaque has blocked your artery, but when you have a mood disorder people attributed it to "chemical imbalances" - pretty vague. New studies are emerging that are helping scientists locate the specific parts of the brain that are affected by bipolar disorder. The good news is the more we know about these cause and effect chains, the more effective the medications become.

While researchers cannot point to one area of the brain that causes someone to exhibit bipolar symptoms, there are a number of regions being studied that art starting to give some clues. The inner most structures of the brain are responsible for processing reward, pleasure, emotion, and memory. Studies show that there is over activity in our reward center that causes people to lose judgment on how certain behaviors (e.g., overspending, sexual activity) may affect them. One of the brain's emotional regulators, the amygdala, seems to be slow to habituate to a response. That is, bipolar people may remain emotionally reactive beyond the usual response time. The memory centers seem to be faulty in the area of helping people recognize danger and safety, resulting in a constant state of anxiety. Higher brain functioning is also problematic in people with bipolar disorders. Brain images of parts of the prefrontal cortex (the part of the brain behind the forehead) show a 20%-40% reduction in gray matter in bipolar people. This part of the brain controls our "executive functioning" - our ability to plan complex behaviors, moderate social control, and differentiate right from wrong. Finally, bipolar patients seem to have a 40% loss of a certain serotonin receptor in the brain stem that may account for depression.