Organic Mental Disorders: Delirium, Dementia and Other Neurocognitive Syndromes
Organic mental disorders are disturbances of cognition, perception, mood or behaviour caused by demonstrable brain disease, systemic illness, toxins, medicines or metabolic disturbance. Current terminology includes delirium, major or mild neurocognitive disorder (dementia), amnestic syndromes and mental disorders due to another medical condition.
Classification and distinguishing features
| Condition | Onset/course | Key features |
|---|---|---|
| Delirium | Hours–days; fluctuates | Impaired attention/awareness, disorientation, altered arousal, sleep reversal, illusions or hallucinations. |
| Dementia | Months–years; progressive or stepwise | Decline in memory and other cognitive domains interfering with independence; alertness usually preserved early. |
| Amnestic disorder | Variable | Marked new-learning/recall impairment; may follow thiamine deficiency, trauma or hypoxia. |
| Medical-condition-induced syndrome | Linked to illness | Psychosis, mood or personality change temporally related to neurological/systemic disease. |
Causes and risk factors
- Neurological: stroke, epilepsy, head injury, tumour, Parkinson disease and other degenerative disorders.
- Infective: malaria, HIV-related CNS disease, meningitis, encephalitis, sepsis and neurosyphilis.
- Metabolic/systemic: hypoglycaemia, electrolyte disturbance, thyroid disease, hepatic/renal failure, hypoxia and nutritional deficiency.
- Substances/medicines: intoxication or withdrawal; anticholinergics, sedatives, opioids and polypharmacy.
- Vulnerability: older age, prior cognitive impairment, sensory loss, dehydration, surgery, immobility and unfamiliar environment.
Assessment
- ABCDE and bedside glucose: treat immediate physiological threats before a lengthy psychiatric interview.
- Collateral history: establish baseline cognition, exact onset, fluctuation, medicines, substances, infection symptoms, injury and function.
- Mental state: attention, orientation, memory, language, visuospatial ability, perception, mood and level of consciousness. Screening supports—but does not replace—clinical diagnosis.
- Physical/neurological examination: vitals, hydration, meningism, focal deficits, gait, tremor, urinary retention, constipation, pain and sensory impairment.
Investigations
Choose according to presentation: glucose, FBC, electrolytes, calcium, renal/liver/thyroid tests, urinalysis/cultures, HIV or malaria testing according to consent and clinical indication, ECG, toxicology, brain imaging for trauma/focal signs or new severe presentation, EEG for suspected non-convulsive seizures, and lumbar puncture when CNS infection is suspected and safe.
Management
Delirium
- Treat the cause: oxygenation, glucose, infection, fluids/electrolytes, pain, retention, constipation and medicine toxicity.
- Support brain recovery: quiet well-lit environment, clock/calendar, familiar caregiver, glasses/hearing aids, sleep preservation, early mobility and adequate nutrition.
- Prevent harm: close observation, falls/aspiration precautions and least-restrictive care. Sedatives may worsen delirium; use medicine only for severe danger or specific withdrawal under protocol, with ECG/respiratory monitoring.
Dementia
- Confirm cause and severity; correct reversible contributors such as depression, sensory loss, medicine effects and nutritional/endocrine disease.
- Use person-centred routines, cognitive stimulation, exercise, occupational support and caregiver education.
- Address behavioural symptoms first through pain assessment, unmet needs and environmental modification. Specialist-prescribed cognitive medicines have diagnosis-specific benefits and require adverse-effect monitoring.
- Plan capacity, consent, safeguarding, driving/work safety, advance care, community follow-up and caregiver respite.
Nursing care plan
| No. | Action | Rationale/evaluation |
|---|---|---|
| 1 | Monitor vitals, SpO₂, glucose, consciousness, intake/output and behaviour trends. | Detects physiological deterioration and response to cause-directed treatment. |
| 2 | Orient calmly; use one-step communication; avoid arguing with misperceptions. | Reduces fear and cognitive overload. |
| 3 | Assist fluids, meals, toileting, skin care and mobility; institute falls precautions. | Prevents dehydration, malnutrition, pressure injury and deconditioning. |
| 4 | Document baseline, fluctuations, triggers, interventions and family observations. | Supports diagnosis, continuity and evaluation. |
Complications and prevention
Complications include falls, aspiration, pressure injuries, dehydration, functional decline, caregiver burnout and mortality from untreated causes. Prevent through medicine review, infection control, hydration, sensory support, vascular-risk management, head-injury prevention, nutrition and early treatment of acute illness.
Revision questions
- Differentiate delirium and dementia.
- Outline the first-hour management of acute confusion.
- Develop four nursing diagnoses with measurable outcomes.
References
- WHO. mhGAP Guideline, 2023.
- Uganda Ministry of Health. Uganda Clinical Guidelines, 2023.