Dementia 3: Delirium

Part 15 of The Mental Health Workers' Guide considers delirium and the dangers of mistaking it for dementia. Don't forget that you can download the video links that accompany this series here.

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Most people understand that physical problems can cause mental confusion. That’s what happens when we get feverish – we become ‘delirious’. There are many types of physical problem that can cause delirium from infection and general illness to inappropriate use of drugs, alcohol and medication. In elderly care one of the major causes of delirium isn’t simply inappropriate ‘use’ of prescription medication but also inappropriate ‘prescribing’ in the first place.

This doesn’t mean that doctors are incompetent when it comes to prescribing medication for elderly people. Rather it is an indication of the complexity of prescribing for an increasingly elderly and often physically frail population.

Delirium can look like dementia in elderly people but it isn’t. The main diagnostic feature is rapid onset and the primary symptom groups are:

• Disorientation to time, place and person;
• Memory impairment;
• Rambling, over-inclusive, seemingly irrelevant or incoherent speech;
• Reduced consciousness;
• Impaired attention to the external world.

There are three basic subtypes:

• Hypoactive (lethargic);
• Hyperactive (overactive);
• Psychotic (hallucinations, delusions & thought disorders)

Body ‘system’ issues in elderly care and delirium

As people age their bodily systems tend to become less efficient. This means that they can be more vulnerable to infection and it’s effects. Bodily systems suffer the effects of ageing such as cardio vascular deterioration and immune system problems.

Metabolic conditions such as diabetes, thyroid problems and liver disease can cause delirium but treating the metabolic problem usually treats the delirium as well. Additionally ‘cognitive reserve’ varies and some (although not all) people become increasingly prone to confusion (not the same as dementia) as part of the normal ageing process.

Delirium versus dementia

Delirium in the elderly is often mistaken for dementia. This is a problem because treatment options are different. This is why any rapid onset confusion needs to be investigated medically as well as psychiatrically. Recent medication changes should also be considered. Infections should be treated promptly in elderly people as they are a major cause of delirium.

Screening for delirium

The ‘standby’ cognitive function screen – the Mini Mental State Examination (MMSE) – is not particularly helpful in identifying delirium. It does pick up signs of confusion but cannot distinguish between delirium and dementia. Much more reliable is the Confusion Assessment Method (CAM) which is interested in the onset of conditions as well as any cognitive or psychomotor symptoms.

Prognosis

Treating delirium won’t impact upon an underlying dementia or other systemic condition but it should be possible to clear the acute delirium symptoms relatively quickly. However some studies have found a residual vulnerability lasting several months following the delirium. This seems to be akin to the neurological ‘kindling effect’ that increases vulnerability after psychotic episodes in younger people.

Simply put, some people remain a little disorientated and more likely to become delirious again for a few months after an episode of delirium.

Delirium is both serious and easy to miss. It is also treatable so long as it can be recognised through proper observation, recording and reporting.

The CAM scale

It’s not necessary to reproduce the Confusion Assessment Method (CAM) scale here. We will simply list the main signs to look out for. This is just a way to ensure that warning signs don’t go unreported and that appropriate assessment is organised in good time.

So look out for:

1   Rapid change or fluctuation in mental state

2   Inattention (distractability, poor focus, shorter than normal attention span)

3   Speech disorder (incoherent, rambling, unpredictable ‘flight of ideas’ or ‘word salad’)

4  Altered consciousness (Very alert, very drowsy, easily startled, unresponsive, lethargic or ‘trance like’).

This list is based upon: 

Inouye SK (1998)

Delirium in hospitalised older patients

Clinical Geriatric Medicine

No. 14, pp 745-764