Acute confusion in an older adult may reflect delirium, medication toxicity, infection, metabolic disturbance, non-convulsive seizures or several problems at once. Distinguishing them is often difficult and sometimes requires EEG.
Delirium fluctuates
Delirium typically causes acute changes in attention, awareness and cognition that fluctuate over hours.
Infection, dehydration, medications and organ dysfunction are common precipitants.
Non-convulsive seizures can look similar
Focal impaired-awareness seizures and non-convulsive status can present with staring, reduced responsiveness, language disturbance or unexplained confusion.
The absence of convulsions does not exclude ongoing seizure activity.
Older brains are more vulnerable
Stroke, dementia, tumour and systemic illness all increase both seizure risk and delirium risk.
That overlap makes diagnostic shortcuts especially hazardous.
EEG is often the deciding test
When altered mental status is unexplained or unusually prolonged, EEG can identify electrographic seizures or patterns on the ictal–interictal continuum.
A short routine EEG may still miss intermittent events.
Treatment depends on the cause
Delirium improves by correcting precipitating illness and reducing harmful medications.
Non-convulsive status requires antiseizure treatment, so the distinction has direct consequences.
Postictal confusion adds a third possibility
A known epilepsy history can tempt clinicians to label all confusion as postictal.
Persistent or atypical confusion still deserves investigation for infection, metabolic disturbance, stroke and non-convulsive status.
Related reading
Sources and further reading
- Non-convulsive status epilepticus and altered mental status
- Antiseizure medications in older adults — 2026
Evidence checked: September 2026.