A patient on long-term antipsychotic treatment has developed abnormal movements. Before revealing the answer, decide what distinguishes akathisia from tardive dyskinesia.

Look at both the timing of onset and the core quality of the movement disturbance. Akathisia can be acute, developing relatively soon after starting or increasing antipsychotic medication, and its core feature is restlessness and inner tension, with an important subjective component of unease that the patient experiences as distressing in itself. Tardive dyskinesia has a later, more gradual ('tardive') onset, typically after longer-term exposure, and its core feature is repetitive, purposeless involuntary movement, most often affecting the mouth, tongue, and face, rather than a felt sense of restlessness. Ask the patient directly whether there is an inner urge to move and a feeling of unease driving it — that subjective quality is characteristic of akathisia and is not a feature of tardive dyskinesia.