• All drugs and alcohol work in the brain. They work by interfering with the brain's normal function to either increase or decrease activity to produce their effects.
• Agonist drugs mimic the brain's natural substances to either stimulate or increase activity in various areas of the brain to produce their desired effect (e.g., increasing feelings of pleasure)
• Antagonist drugs mimic the structure of the brain's natural substances enough to block and decrease activity in various areas of the brain to produce their desired effect (e.g., counteracting an overdose)
• How drugs work remains the same for autistic people as non-autistic people, but the way autistic people experience a drug may be different. The reward pathways involved in addiction may be regulated differently in autistic people, however, research is very limited and theoretical

Generally speaking, all drugs and alcohol work in the same way. Regardless of whether it is an illegal drug or one prescribed by a doctor, all drugs and alcohol work in the brain.

All drugs (including alcohol) work primarily within the brain, more specifically, on the "receptors" within the brain. These receptors receive chemical information produced in the brain from other parts of the brain and are responsible for generating signals within the brain. The production of these signals lead to a variety of different effects, such as making us feel pain or experiencing happiness.

All drugs work by interacting with various receptors (depending on the drug) to produce one of two base effects; either to increase activity (known as agonist drugs), or to inhibit activity (known as antagonist drugs).

Normally, the brain produces natural substances, known as neurotransmitters.

Different neurotransmitters are constructed differently, meaning that they can only interact with a receptor with the corresponding construction. For example, the neurotransmitter dopamine can only bind to a receptor that can accommodate for dopamine.

When the neurotransmitters are released by the brain, they bind to the receptor, which creates the desired signal. The effect of the signal depends on the binding of the neurotransmitter to the receptor, meaning the more neurotransmitters are released, the bigger the signal and effect. 

Agonist drugs work by resembling, or mimicking the same construct as a particular neurotransmitter.

The agonist drug is not a complete copy, it just needs to be a good enough copy to fool the receptor into thinking it is the required neurotransmitter.

The agonist drug then binds to the receptor in place of the natural neurotransmitter, which then results in the production of the signal.

This can produce the same signal response as in the normal process or an increased response, as there are more substances to bind to the receptor.

For example, the active ingredient in cannabis (known as THC) binds with the cannabinoid receptors in the brain to produce the various feelings associated with its use (such as feeling "stoned" or giggly). The variation in these feelings is due (in part) to the location of these receptors in the brain.

Antagonist drugs act in an opposite way to agonist drugs. Instead of increasing binding to receptors and creating normal or increased activity of signals, antagonist drugs aim to stop the production of these signals.

Antagonist drugs work by resembling a particular neurotransmitter. However, the resemblance is not enough to bind with the receptor and produce the normal signal response.

Instead, the antagonist drugs get stuck within the receptor site, preventing the natural neurotransmitters and the agonist drugs from binding with the receptor. This blocks the production of the signal and prevents the signal being activated by the usual methods.

Certain antagonist drugs can be used to combat agonist drugs. For example, if someone is experiencing an overdose of opioids (such as morphine), the antagonist drug naloxone can be given to bind to the opioid receptors, preventing the morphine from binding with receptors, which can reverse the effects of the overdose.

Additionally, some substances can be both agonist and antagonist. For example, alcohol acts as both an antagonist on certain receptors and an agonist on other receptors.

Generally speaking, the mechanism of how drugs and alcohol work is the same for autistic people as it is for non-autistic people.

However, the effects and experiences produced by certain drugs or alcohol may be different for autistic people.

Some researchers theorise that the areas of the brain involved in addiction may be different in autistic people. More specifically, the reward pathways of the brain and the neurotransmitter dopamine. The pleasurable feelings of taking a drug or alcohol are achieved through the release of dopamine in the reward pathways of the brain, which is thought to reinforce the repeated use of the drug or alcohol.

If the systems involved in the regulation of the reward pathways are different for autistic people, then potentially, drugs and alcohol may act differently or are experienced differently for autistic people.

However, no research to date has looked at whether drugs, alcohol or addiction affect autistic people differently. These theories are usually discussed in relation to the development of autism itself.

With the increased attention and interest in the subject of alcohol, drugs and addiction in autistic people, more research may be conducted on the affects.