Ocd mainly affects the front part of the brain which controls the perception of danger or fear, and the ability to start and stop different thoughts and activities. Basically, that's the perfect formula for Obsessive-Compulsive Disorder. Many researchers have linked the ultra high activity in the front of the brain to an abonormal functioning of the nuerotransmitter, serotonin. It's been shown that through more PET scans that taking medications that have serotonin will decrease the activity in the brain as shown in the picture below.
Taking medication will not cure the disorder, since there is no cure, but it does aid in helping the person to control it overall. Medication is only half of the treatment for obsessive-compulsive disorder. The other half is CBT (Cognitive-Behavioral Therapy). Along with CBT comes daily assignments and a rating system to help gauge anxiety levels. CBT makes a person face their fears, but at a controllable anxiety level. Ultimately the patient in CBT has the complete control to decide what they want to do and how fast they try to accomplish it. Speaking from experience, it basically sucks while you're doing it but it works! It takes a lot of dedication, hard work, and support from loved ones to get through, but once your first fear is accomplished ocd doesn't seem so big. There might not be a cure, but there's definitely hope to live a happy life!