The brain is the most dynamic and complex organ in our bodies. The brain's proper functioning ensures our very survival. When our brains function well, we are constantly adapting to our environment (our surroundings). Ironically, it is the brain's ability to be so adaptive that contributes to the formation of addiction. Addiction causes changes to the brain in at least four fundamental ways:
1. Addiction causes changes to the brain's natural balance (homeostasis).
2. Addiction alters brain chemistry.
3. Addiction changes the brain's communication patterns.
4. Addiction causes changes to brain structures and their functioning.
1. Addiction changes the brain's natural balance (homeostasis).
Addiction interferes with an important biological process called homeostasis. Scientists consider the human body a biological system. All biological systems attempt to maintain a "normal" balance, known as homeostasis. The brain functions as the "overseer" of this balance. It makes various adjustments to maintain a balanced, well-functioning, biological system. Each person's "normal" balance is individually determined. Drugs of abuse and activity addictions lead to changes in this normal balance.
Chronic over-stimulation of the brain (like that which occurs in addiction) interferes with the maintenance of this balance (homeostasis). When the brain has difficulty maintaining homeostatic balance, the wonderfully adaptive brain makes adjustments. It does this by creating a new balanced set-point. The creation of a new balance is called allostasis.
These concepts are easier to understand if we use example more familiar to most people. Suppose I gain 10 lbs. At first, I will just keep trying to fit into my clothing. However, tight clothing is uncomfortable. At some point, I must adapt to the change in my body size. I will eventually acknowledge I need to buy larger clothing. Once I buy larger clothing, I am more comfortable. I've come to accept that my clothing size is now size Large, whereas before it was size Medium. In effect, I changed my "homeostatic balance" from size Medium to size Large. Having reset my size to "Large" I am now more comfortable. Keep in mind, if I lose those 10 lbs. to achieve greater health, I will again have to readjust my clothing size. So, even though I am now healthier, I still have to make an unpleasant and costly adjustment; i.e., buying all new clothes in a smaller size. This is very similar to the unpleasant adjustment the brain must go through when people try to give up their addiction. Although this is a positive change, we will be uncomfortable while the brain readjustments itself.
Ironically, the brain's wonderful ability to be so adaptive (via allostasis) causes significant changes to the brain's functioning. These changes account for many behaviors associated with addiction such as: 1) the powerful need to obtain drugs or continue harmful activities despite the harm to self or loved ones, 2) the difficulty of quitting an addictive drug or activity, and 3) the obsessive, all-consuming nature of addictions such that little else in life matters. This is because addiction caused the brain's balance to change to accommodate the addiction. Once changed, the brain requires the addictive substance or activity in order to maintain this new homeostatic balance.