How do antipsychotic drugs increase the risk of TD?
Although it is not clear how antipsychotic drugs do what they’re supposed to do, much less how they increase the risk of TD, it is know that they change how nerve impulses jump from one set of nerve cells (pre-synaptic neurons) across a gap (synapse) to another set of nerve cells (post-synaptic receptors). The impulses are carried by substances called “neurotransmitters.” Anti-psychotic drugs block a particular neurotransmitter called “dopamine,” allowing little of it to reach the post-synaptic receptors. It is assumed (but not proven) that dopamine blockades in various nerve pathways of the brain cause the unwanted effects of antipsychotic drugs, including TD. According to one hypothesis, the dopamine blockade results in the post-synaptic receptors becoming hypersensitive to the little dopamine that does leak through. Constant (and possibly increasing) doses of medications may be needed to keep dopamine from playing havoc with the hypersensitive receptors. Perhaps no single hypothesis
