What are neurocognitive disorders due to other medical conditions?

These diagnoses describe cognitive decline (mild or major) that is a direct consequence of a general medical condition — for example, stroke, traumatic brain injury, infection, metabolic or endocrine dysfunction. The cognitive impairment should be clearly linked temporally and biologically to the medical condition and not better explained by another disorder.

Common medical causes

• Vascular events: ischaemic or haemorrhagic stroke, chronic small vessel disease.
• Traumatic brain injury (TBI): single or repetitive injuries leading to lasting deficits.
• Infections: HIV-associated neurocognitive disorder, chronic meningitis, neurosyphilis, post-encephalitic syndromes.
• Metabolic & endocrine: hypothyroidism, hypercalcaemia, severe hypoglycaemia, hepatic encephalopathy, renal failure (uremic encephalopathy).
• Vitamin deficiencies: B12, thiamine (Wernicke-Korsakoff spectrum), folate.
• Hypoxic‑ischaemic injury: cardiac arrest, respiratory failure.
• Autoimmune & inflammatory: autoimmune encephalitis, systemic lupus erythematosus.
• Tumours & mass lesions: primary or metastatic brain tumours, normal-pressure hydrocephalus.
• Chronic systemic illness: severe COPD, congestive cardiac failure, untreated sleep apnoea.

Core cognitive and behavioural features

• Domain-specific deficits depending on lesion/location — e.g., aphasia after left MCA stroke, executive dysfunction with frontal lesions.
• Global slowing of processing and attentional fluctuations (common in metabolic causes).
• Memory impairment — often retrieval-based in vascular or subcortical processes; consolidation deficits with medial temporal involvement.
• Behavioural changes: apathy, irritability, mood disturbance, psychosis (in infections or metabolic encephalopathies).

Assessment — clinical priorities

1. Establish temporal relationship between medical event and cognitive decline.
2. Detailed neurological and cognitive examination (domains: attention, executive function, memory, language, visuospatial skills).
3. Review medications for iatrogenic contributors (anticholinergics, sedatives, opioids).
4. Screen for delirium — fluctuating course requires prompt treatment of underlying medical cause.
5. Collateral history from family, caregivers and medical records.

Essential investigations

• Blood tests: CBC, electrolytes, renal and liver function, glucose, thyroid function, B12, folate, inflammatory markers.
• Screen for infection: HIV, syphilis serology, relevant cultures.
• Neuroimaging: CT head (acute), MRI brain (structural lesions, small vessel disease, tumours).
• EEG if seizures or encephalopathy suspected.
• CSF analysis when infection or autoimmune encephalitis suspected.
• Neuropsychological testing for domain-specific profiling and baseline measurement.

Treatment & management principles

Address underlying medical causes first; support cognition and function while minimising harm. Management is multidisciplinary — medicine, neurology, psychiatry, rehabilitation and social care.

Medical management

• Correct metabolic derangements, treat infections, optimise organ function (renal, hepatic, respiratory).
• Vitamin repletion (B12, thiamine) when deficient.
• Reduce or stop offending medications (anticholinergics, benzodiazepines, sedative analgesics) where safe.
• Surgical/interventional treatment where relevant (tumour resection, CSF diversion for NPH).

Cognitive & rehabilitative care

• Neuropsychological rehabilitation — compensatory strategies, memory aids, cognitive training tailored to deficits.
• Occupational therapy for ADL and safety, physiotherapy for mobility and balance.
• Speech and language therapy for aphasia or swallowing difficulties.

Psychiatric & behavioural support

• Treat mood and psychotic symptoms when present — prefer agents with lower anticholinergic burden.
• Non-pharmacological behavioural strategies to reduce agitation and caregiver stress.

Care planning

• Early discussion on capacity, driving, finances and advance directives when appropriate.
• Provide caregiver education, respite and community resources.

Key takeaways

• Always consider reversible medical causes when assessing cognitive decline.
• Detailed history, collateral information and targeted investigations are essential.
• Early treatment of underlying medical issues can improve or reverse cognitive impairment in many cases.
• Management requires a multidisciplinary approach and attention to caregiver needs and safety planning.