Pleasure Unwoven III: Is Addiction a Disease?

https://www.youtube.com/playlist?list=PLA8F89537FD4C3FD1

(continued)

In order to identify the things in the environment essential to survival, the midbrain makes them pleasurable. This is the hedonic capacity, the pleasure sense. But “pleasure” has moral implications in our society. Addiction is a defect in the ability of the brain to perceive, act upon, and process pleasure.

Several processes in the brain combine to create a pleasure construct including involuntary memory. The brain weaves emotion, memory, sights, sounds, smells into a single sensation. Each level of processing is based on the lower levels and a defect at a lower level is passed up to the higher levels.

There are 5 theories in neuroscience addressing addiction – these correspond to the levels of brain processes. They are complimentary rather than mutually exclusive:

1. Genetics

Everyone is at some risk for addiction but some are more susceptible than others. 40-60% of the vulnerability to addiction is genetic. But something in the environment has to turn these genes on. An analogy is to compare how water can shape rock with how experience can turn these genes on. A critical point is that genes can also be turned off.

1. Midbrain reward processing

The neurotransmitter dopamine is released by the midbrain. This tells the brain when a reward (again the point ultimately being survival and propagation of ones genes) is noticeable, important, salient, and, most importantly, when a reward is better than expected. When a reward is better than anticipated there may be implications for survival. The hedonic system is a learning signal which identifies, processes, and anticipates rewards. This is why addiction is more about drug-wanting than drug-liking. Things like food and sex release dopamine. Drugs, in part, use dopamine to fool the brain and eventually they climb to dominate the survival list. This is why addicts persist in using despite consequences. A critical implication of this mechanism is that when one develops a problem with one drug there is a liability to have problems with any and all other drugs (weed, alcohol, opiates, hallucinogens, stimulants, benzos). There can also be behavioral cross-addictions: food, sex, gambling, codependency.

1. Memory

Glutamate is the neurotransmitter involved in memory formation. It encodes natural rewards based on signals from the midbrain (dopamine). Glutamate is the chemical of drug memory and drug seeking. The neurons send dopamine up (this is important, I want this) and neurons send glutamate down (OK, I’ll remember, Ok go and get it). Drugs interfere with this communication. Each instance of drug use creates a flashflood of neurotransmitters and ravages the brain. Neural pathways strengthen or weaken with use. Addiction is a form of overlearning and hypermemory.

1. The stress system

The anti-reward system. The chemical CRF to counteract dopamine to maintain balance and homeostasis. Repeated drug use leads to a chronic overstimulation of the stress system. It changes a person’s hedonic set point to where normal pleasures no longer register. This is and a person can become “pleasure dead.” The brain craves drugs because it now sees them as the best stress reliever. The connection between drugs and survival literally becomes subconscious.

1. The frontal cortex

Problems at the lower levels of processing are all compounded here. It turns out that free will is completely contingent in the processing of feeling. This may be inconvenient to some with certain long and deeply-held beliefs but decades of gold-standard, peer-reviewed, independent research using everything from experiments with identical twins separated at birth to PET and functional MRI scans, blood tests, behavioral observations, etc. completely obliterate such views founded upon nothing other than arbitrary authority and accidental historical contingency.

CONTINUED IN NEXT POST