Synopsis
Distinguish primary psychiatric syndromes from delirium, neurological disease, systemic illness, medicine effects and substance states using chronology, attention, physiology, examination and targeted tests while recognising that causes can coexist.
- Start with time course: abrupt and fluctuating change suggests delirium, intoxication, withdrawal, seizure or other acute disease more than an uncomplicated primary psychiatric syndrome.
- Establish attention and arousal before interpreting unusual beliefs or perceptions; impaired attention makes routine psychiatric and cognitive conclusions less reliable.
- Compare with baseline using collateral information and identify recent illness, pain, surgery, sleep loss, medicine changes, substances and head injury.
Key red flags
Inattention and altered arousal are core clues to delirium and should not be explained by agitation, depression or dementia without a cause assessment.
Investigation priorities
Establish speed, fluctuation, previous episodes, illness, medicines, substances, trauma and functional change.
Management branches
A patient presents with new behavioural, perceptual, cognitive or mood change.
- Establish last known baseline, onset, fluctuation, exposures and physical symptoms using collateral evidence where needed.
- Assess observations, glucose, attention, arousal and immediate neurological or systemic warning signs before assigning a psychiatric label.