Numerous medical conditions can produce psychotic symptoms through direct physiological effects on brain function. These organic psychoses require accurate identification, as treatment must address the underlying pathology rather than merely managing psychiatric symptoms.

Neurological and Autoimmune Disorders

Several brain-specific conditions directly disrupt neural networks.

• Autoimmune Encephalitis. Antibodies targeting neuronal structures, particularly NMDA receptors, frequently cause acute psychosis with prominent movement abnormalities and autonomic instability. These cases illustrate how medical conditions can trigger psychosis through immune-mediated mechanisms.
• Temporal Lobe Epilepsy. Complex partial seizures can produce olfactory hallucinations, religious delusions, and intense perceptual distortions during ictal or postictal periods. This demonstrates how medical conditions can trigger psychosis through episodic electrical disturbances.
• Neurodegenerative Diseases. Lewy body dementia, Parkinson's disease, and Huntington's disease commonly feature visual hallucinations and paranoid ideation as core symptoms due to progressive neurotransmitter system disruption.

Metabolic and Endocrine System Dysfunction

Systemic physiological imbalances significantly impact cerebral functioning.

• Thyroid Dysfunction. Both severe hyperthyroidism and hypothyroidism can induce paranoid delusions and hallucinations through altered cerebral metabolism and neurotransmitter regulation.
• Adrenal Disorders. Cushing's syndrome and Addison's disease frequently cause mood disturbances and psychotic symptoms via cortisol-mediated effects on hippocampal and prefrontal function.
• Electrolyte Imbalances. Severe sodium, calcium, or magnesium disturbances disrupt neuronal signaling, potentially causing transient psychotic states that resolve with correction.

Systemic and Infectious Diseases

Various systemic illnesses secondarily affect brain function.

• Systemic Lupus Erythematosus. Neuropsychiatric lupus can present with psychosis due to autoimmune-mediated cerebral vasculitis and antibody deposition.
• HIV-Associated Neurocognitive Disorder. Direct viral effects and opportunistic infections can cause psychotic symptoms through frontal-subcortical circuit disruption.
• Hepatic and Renal Failure. Accumulated toxins in end-stage organ failure produce encephalopathies characterized by fluctuating consciousness and psychotic features.

These examples demonstrate why comprehensive medical evaluation remains essential when psychosis presents atypically. The clinical features that suggest an organic etiology include rapid symptom onset, older age at first presentation, abnormal vital signs, and concurrent cognitive impairment. Accurate diagnosis ensures appropriate treatment targeting the underlying pathophysiology rather than symptomatic management alone.