Addiction, substance abuse and dependence
What is substance abuse?
Substance abuse refers to ‘the harmful or hazardous use of psychoactive substances, including alcohol and illicit drugs.’ Many will experience substance abuse at some point, like with binge drinking, but it can become very problematic when it occurs on a regular basis. For example, it can lead to drug dependence which is the body’s physical need, or addiction, to a specific agent. Addiction severely places a burden on society due to its repercussions on healthcare and crime rates.
Why are certain drugs addictive?
Drugs are said to ‘kidnap’ our brain reward circuits through increasing feelings of pleasure, for example many drugs increase dopamine release. Our body is designed to have reward pathways to ensure we do things that promote survival. When we do, we are rewarded with a signal. Remember when you were exercising and it was excruciatingly painful, then suddenly it starts to feel good? Our bodies release endorphins which help with pain relief. We start to feel good again and it makes us more inclined to do more exercise. That is a reward pathway. We are rewarded for exercising as exercising has several benefits for our survival. Other actions are drinking water, food consumption, procreation, and child nurturing. They are called ‘natural reinforcers,’ once we get that reward, we are incentivised to do it again. That is why we say drugs kidnap these pathways. Many drugs increase the reward feelings, so much so, that the ordinary release of dopamine is not satisfactory enough so people seek to use drugs again. Incentive salience is described as a cognitive process which confers a ‘desire’ or ‘want’ attribute, including a motivational component, to a rewarding stimulus.
There are two types of dependence, physical and psychological. Physical dependence results from adaptation by resetting homeostatic mechanisms in response to repeated drug use. Someone who is physically dependent will experience withdrawal symptoms when not taking the drug. Withdrawal is direct evidence of physical dependence, so is an easy way to tell when someone is addicted. Withdrawal arises from an abrupt termination of use, hence why, some rehabilitation treatment, they will provide the drug in lowering doses to avoid the withdrawal. Withdrawal can be very unpleasant and is a large reason for why those addicted struggle to obtain abstinence.
Psychological dependence is the motivational component, where one will experience a craving for the drug. Psychological dependence is not always associated with physical dependence, as your body may not physically be needing the drug but your mind might. Certain drugs, like cocaine have psychological dependence that can persist for very long periods.
With repeated use, tolerance starts to develop. Tolerance is the reduction in response to the drug after repeated administrations. Therefore, one would need to increase concentrations of drug to get the same effect. There is innate and acquired tolerance. Innate tolerance is a genetically determined sensitivity, it will be present after your first dose. Acquire tolerance occurs due to changes in metabolism leading to an altered response to the drug. Some drugs can also give cross tolerance, where taking one drug can provide tolerance to another drug.