Tag Archives: nucleus accumbens

Anorexia, Addiction and the Three-Part Brain Model

The Three-Part Brain Model

The American Society of Addiction Medicine defines addiction as “a primary, chronic disease of brain reward, motivation, memory and related circuitry. Dysfunction in these circuits leads to characteristic biological, psychological, social and spiritual manifestations. This is reflected in an individual pathologically pursuing reward and/or relief by substance use and other behaviors.

Addiction is characterized by inability to consistently abstain, impairment in behavioral control, craving, diminished recognition of significant problems with one’s behaviors and interpersonal relationships, and a dysfunctional emotional response. Like other chronic diseases, addiction often involves cycles of relapse and remission. Without treatment or engagement in recovery activities, addiction is progressive and can result in disability or premature death.”

To understand addiction, it is important to understand the three-part brain model. The first and most important part of the brain is the lower part of the brain, the brain stem. The brain stem regulates life sustaining activities such as telling us to breath, getting our digestion going and regulating heart rate.

The next most important part of the brain is the middle part of the brain, the limbic system. The limbic system is responsible for emotional, instinctual, and motivational-based functions. It gets us to do things that will keep us alive. The middle part of the brain is the non-thinking part of the brain that instinctually and reactively gets us away from pain or draws us toward pleasure (such as sex, food, sleep, exercise etc) which is a life-sustaining principle.

The third and final part of the brain is top part of the brain, the cortex. The cortex is the thinking part of the brain. It gives the ability to appreciate art, literature and other people. Additionally, it is responsible for our social skills, judgment, insight, and other executive functions of the brain. The cortex also moderates emotions and instincts which are there to keep our lives going.

In a perfect system, all three parts of the brain will work together in balance. When a problem occurs, such as addiction or an eating disorder the limbic system becomes manipulated or overbalanced. What was initially a perfect system actually begins to work against us; the middle part of the brain overpowers the top part of the brain. When the middle part of the brain becomes aroused by feelings such as hunger, anger, loneliness, or tiredness we lose our sense of willpower and reasonable thinking; which resides in the front part of the brain.

The middle part of the brain is home to the nucleus accumbens. The nucleus accumbens is the reward pathway of the brain; anything that makes us feel good involves the nucleus accumbens. Three of the neurochemicals that pass through the nucleus accumbens include dopamine, serotonin, and endorphin. Dopamine is the neurochemical that makes us want or desire something; serotonin is the neurochemical makes us feel relaxed and satisfied; endorphin is the neurochemical that protect us from feeling physical or emotional pain.

I recently spoke to addictions specialist Dr. Vera Tarman who described how this relates to the brain of an individual with anorexia. When an individual is suffering from anorexia they experience a dopaminergic euphoria. He or she experiences a ‘high’, as they obsess about food; similar to how a drug addict would experience over their drug of choice.  When the anorexic becomes increasingly hungry, the limbic system produces extra dopamine. As the person becomes hungrier, the reward value of food heightens. This is the body’s attempt to entice the person to eat, to nourish itself. The anorexic does not eat food, but as he or she gets hungrier, she instead anticipates food – in the food preparation, in the food obsessions, in how she or he ‘plays’ (but does not eat) the food. As the anorexic individual becomes more and more hungry, the dopamine high builds and builds. It’s important to note that as soon as the anorexic does eat, the high stops completely. Anorexics resist food the same way as the drug addict resists withdrawal from their drug.

Sources:

Human Brain and Skeleton Photo from office.microsoft.com Clip Art and Image Library (Under Creative Commons Attribution 3.0 License) Source: knol.google.com

American Society of Addiction Medicine. (April 19 2011). Definition of Addiction. American Society of Addiction Medicine. Retrieved July 18 2012, from http://www.asam.org/for-the-public/definition-of-addiction.

Dr. Vera Tarman (personal communication, July 11, 2012)

Croxton, S. (Host) (2012, May 23). Understanding Food Addiction with Dr. Vera Tarman [Podcast]. Underground Wellness. California: Blog Talk Radio. Retrieved May 24 2012, from http://www.blogtalkradio.com/undergroundwellness/2012/05/23/understanding-food-addiction-w-dr-vera-tarman

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