A patient presents with severe agitation and paranoia after taking a stimulant. Which condition should be suspected?

When a patient exhibits severe agitation and paranoia following the consumption of a stimulant, stimulant-induced psychosis is indeed the most appropriate condition to suspect. This condition occurs as a result of the pharmacological effects of stimulants, which can elevate neurotransmitter levels in the brain, particularly dopamine.

The symptoms, such as agitation and paranoia, can manifest as a direct consequence of the stimulant's impact on the central nervous system, potentially leading to hallucinations and delusions. The timeline in which the symptoms occur—that is, shortly after the stimulant use—also supports this diagnosis, as stimulant-induced effects typically present rapidly following exposure to the substance.

The other conditions, while they may present with some overlapping symptoms such as agitation or altered mood, do not specifically correlate with the direct causative link of stimulant use resulting in psychotic features. For example, agitated depression is characterized more by persistent depressive symptoms with agitation rather than acute psychotic episodes. Substance-induced mood disorder generally pertains to disturbances in mood rather than overt psychosis resulting from stimulants. Acute stress disorder involves symptoms that arise following exposure to a traumatic event, not through stimulant use itself.

Hence, the presence of severe agitation and paranoia in this context points strongly toward stimulant-induced psychosis as the most fitting diagnosis