What receptor is involved in a young man presenting with visual hallucinations, thinking he is in a police station, with hypertension (High Blood Pressure), dilated pupils, and diaphoresis?

From the FDA Drug Label

The pressor response to ketamine is reduced or blocked by chlorpromazine (central depressant and peripheral α-adrenergic blockade), by β-adrenergic blockade, and by ganglionic blockade. The NMDA receptor is involved in the presentation of a young man with visual hallucinations, thinking he is in a police station, with hypertension, dilated pupils, and diaphoresis, as ketamine, an NMDA receptor antagonist, can cause these symptoms 1.

• The symptoms presented are consistent with the effects of ketamine, which include psychological manifestations such as hallucinations and emergence delirium 1.
• The pressor response to ketamine, which contributes to hypertension, is mediated by central cardiac stimulating mechanisms and can be reduced by α-adrenergic blockade and β-adrenergic blockade 1.

From the Research

The correct answer is the NMDA (N-methyl-D-aspartate) receptor, as it is most closely associated with the clinical presentation of visual hallucinations, confusion, hypertension, pupillary dilation, and diaphoresis. This clinical presentation is consistent with anticholinergic toxicity or delirium, which involves NMDA receptor dysfunction. The patient's symptoms are classic manifestations of anticholinergic syndrome or similar states of delirium. NMDA receptors play a crucial role in cognitive function, memory, and perception. Dysfunction or antagonism of these receptors (as seen with drugs like ketamine, PCP, or in certain toxic states) can lead to hallucinations and altered mental status, as discussed in the study by 2.

Key Points

• The patient's symptoms of visual hallucinations, confusion, hypertension, pupillary dilation, and diaphoresis are consistent with NMDA receptor dysfunction.
• NMDA receptors are involved in cognitive function, memory, and perception, and their dysfunction can lead to hallucinations and altered mental status.
• The study by 3 discusses the pharmacological mechanisms of hallucinations, including the role of NMDA receptors.
• Other studies, such as 4 and 5, also support the involvement of NMDA receptors in hallucinations and cognitive dysfunction.

Relevant Evidence

• The study by 3 provides a narrative review of the literature on the pharmacology of hallucinations, including the role of NMDA receptors.
• The study by 4 investigates the effects of NMDA receptor antagonists on serotonin efflux in the medial prefrontal cortex.
• The study by 5 examines the relationship between serotonin-2A receptor availability and cognitive functions in nondemented Parkinson's disease patients with visual hallucinations.
• The study by 2 discusses the NMDA receptor hypofunction hypothesis and its relationship to positive and negative symptoms in schizophrenia.