What initial investigations are recommended for a patient experiencing visual hallucinations in primary care?

For a patient presenting with visual hallucinations in primary care, the initial investigations should focus on identifying reversible causes and underlying conditions that may explain the symptoms. This includes:

• Taking a detailed history including cognitive, behavioural, and psychological symptoms, and the impact on daily life, from the patient and, if possible, someone who knows them well.
• Conducting a physical examination to identify any neurological signs or other relevant findings.
• Ordering appropriate blood and urine tests to exclude reversible causes of cognitive decline or delirium, such as infections, metabolic disturbances, or medication effects.
• Using cognitive testing with validated brief structured instruments (e.g., 6CIT, Mini-Cog) to assess cognitive impairment.
• Considering referral to a specialist dementia diagnostic service if dementia or neurodegenerative causes are suspected after initial assessment and reversible causes have been excluded.
• Offering structural brain imaging (CT or MRI) to rule out reversible causes such as brain lesions or vascular pathology, especially if cognitive decline or neurological signs are present.

These steps help to differentiate causes such as dementia with Lewy bodies, delirium, or other neurological disorders that can present with visual hallucinations. Further specialist investigations may be warranted based on initial findings.

This approach aligns with NICE guidance on dementia assessment and management, which includes investigating reversible causes and using cognitive testing and imaging as initial steps in primary care before specialist referral ².