Delirium, or an acute state of confusion, occurs commonly in the elderly, usually due to underlying physical illnesses or disorders, and is linked to caregiver distress and hospitalisation.

It occurs in 20-40% of patients in the hospital intensive care unit and is much more common in mechanically ventilated patients. Age is a risk factor for developing this condition, which is detected by careful assessment which includes information from caregivers and family members, and observation, physical examination, laboratory tests and scans.

In terms of symptoms, family members may report that the elderly person has become suddenly confused, is not able to recognise time, place and persons around them. The person can experience lowering of consciousness towards evening and night times, with their behaviour becoming more unresponsive and unmanageable with the setting sun, a phenomenon known as the “sun downing” effect. The elderly may also experience perceptual abnormalities such as visual or auditory hallucinations. Some patients with delirium may experience persecution or severe anxiety, which could motivate them to attempt to leave the home or hospital, often displaying aggressive behaviour.

Diagnosis is typically through physical examination and laboratory investigation. Common causes include urinary tract (UTI) or chest infections, which can be detected and treated early. Delirium could be linked to abnormally low levels of sodium, which may stem from various medical conditions or medications taken for high blood pressure or antidepressants, or excessive water intake.

Cardio- or neuro-vascular events occur due to clots or blockages in the blood vessels, leading to strokes or heart attacks. In such cases confusion can be one of the signs that suggest an imminent threat to life, requiring emergency intervention. Chronic alcohol abusers may face withdrawal symptoms upon sudden discontinuation of the substance, and this can lead to a condition called delirium tremens, with the risk of fits and mental confusion. Many elderly patients experience confusion after surgical procedures, sometimes because of anaesthesia.

Research on the causes of delirium is ongoing, with no conclusion yet. One theory is that the elderly are sensitive to immune mediating chemicals, which means when the body is trying to repair from the sick state, the chemicals that are released during the process contribute to the delirium. This effect of immune modulators may go unnoticed in adults, but the higher sensitivity of the brains of the elderly to these chemicals could cause the condition.

Management of delirium could be through avoiding bright light or darkness, noise, excessive stimulation, ensuring adequate food and fluid intake, ensuring regular bowel and bladder habits and the sleep-wake cycle. Repeated reorientation is needed, making the caregiver’s role important. The risk of falls is high and it will be necessary to plan for regular pulse and blood pressure monitoring. More broadly, promoting understanding of and awareness about this condition among the family, friends and carers of the elderly can lead to much more reassurance, particularly where the cause is a minor infection.

Vijaykumar Harbishettar is a Consultant Psychiatrist and ad hoc faculty in Geriatric Psychiatry in NIMHANS, Bangalore

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