It is not always what it seems.
Medication can affect the functioning of the brain and can therefore be considered as a form of neuromodulation. Many medications that act on the brain are products that are very similar to the chemicals that the brain itself produces. The classic description of medication, such as 'serotonin is an antidepressant' or 'dopamine is an antipsychotic', is outdated. For example, the pain-suppressing pathway in our brains works on the basis of opioids, serotonin and dopamine. Therefore, serotonin preparations can also be useful in people with chronic pain, without depression. The medication is then given to activate that pain-inhibiting path, but not as an antidepressant.
Sometimes people are particularly focused on a specific symptom, for example pain or tinnitus, which means they pay less attention to other sensations. Behind this process is a biological mechanism. Dopamine D1 receptors are among other examples involved in this exaggerated observation. Medication that blocks dopamine D1 receptors can help reducing that increased focus.
Other medications such as Clonazepam is actually an anti-epileptic, but prevents the side effects of dopamine blockers. Gabapentin, another anti-epileptic, works pain-suppressing and is mood-stabilizing.
Some antibiotics have a protective effect on the brain, even in people without infection.
Medication that stimulates most people, such as methylphenidate, may have an opposite effect in others, for example people with ADHD, and may actually have a calming effect.
The prescription of medication is based on the neurotransmitter of the brain circuits that we try to influence. Sometimes the effect of the drug is separate from what the label represents (such as antidepressant, antipsychotic, anti-epileptic, etc.).
Which dose is given?
Medication can be given to support too low a production of a specific substance by the own brain. The lowest possible dose is chosen because high doses can sometimes have a reverse effect. This is called an 'inverted U profile'. In addition, high doses can cause more side effects.