Old age psychiatry

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CHAPTER 17 Old age psychiatry

David Ames, Edmond Chiu, Daniel O’Connor, Nicola Lautenschlager

The world is ageing. Population ageing leads to more people being affected by disorders whose prevalence rises with age, such as dementia. The proportion of Australians aged 65 and over is expected to double from 13% to 27% of the total population between 2006 and 2051. Past high birth and immigration rates, which have fallen dramatically since the 1970s, are the main reasons for this demographic change. Older people form a smaller proportion of the population in developing countries, but their numbers are growing quickly. The median age of people in China will rise from 30 to 45 years by 2050, when over a third will be aged above 60.

Although most elderly Australians are well and have a good quality of life, it is not unusual for very old people to be widowed, to live alone and to have health problems that limit independence. Over half enter residential care eventually.

The specialty of old age psychiatry offers assessment and treatment to older people with mental disorders. Old age psychiatry is a multidisciplinary specialty and requires teamwork. All doctors need to display patience and compassion, especially when dealing with the old and frail.

Dementia

Dementia is an acquired decline in higher mental functioning (especially memory, intellect and personality) occurring in an alert patient (to distinguish it from delirium) that affects multiple cognitive functions (not just memory) and interferes significantly with everyday function. Most dementias are irreversible and progressive.

Currently, over 27 million people worldwide are affected by dementia, and this number is projected to double every 20 years, surpassing 100 million by 2050. After age 60, the prevalence rate of dementia doubles every 5 years, rising from 1% at age 65 to 25% at age 85 (see Box 17.1 for the main causes of dementia in Australia). Most new cases will appear in developing countries. However, Australia will experience a big rise from 200,000 (1% of the population) in 2006 to 730,000 (2.8%) by 2051. In 2005, 25,000 Australians were newly diagnosed as having dementia, but, by 2050, 175,000 new cases will arise annually.

BOX 17.1 Causes of dementia in Australia

• Alzheimer’s disease (AD): 50%

• mixed AD and cerebrovascular disease: 20%

• pure vascular dementia: 5%

• dementia with Lewy bodies and Parkinson’s disease dementia: 10%

• primary frontotemporal dementias: 5%

• alcohol-induced dementia: 5%, and

• other rare dementias: 5%.

Clinical presentation

Dementias affect memory, intellect, behaviour and personality. Usually, loss of insight causes problems to be brought to medical attention by relatives. Dementia often leads to poor hygiene and diet, unsafe use of appliances, failure to pay bills and getting lost. Repetitive questioning, night-time disturbance and challenging behaviours can distress family members.

The symptoms listed in Box 17.2 are referred to as ‘behavioural and psychological’, or ‘neuropsychiatric’, symptoms of dementia. Some are common (60% of people with dementia living at home exhibit one or more of these symptoms), most upset either the person with dementia or those around them, and they may lead to the prescription of psychotropic medication.

Assessment of the person with suspected dementia

History

To ascertain the nature and extent of cognitive deficits and establish their cause, determine their impact on function, diagnose comorbid delirium or depression, and check the available supports, a good history is needed. Information should be obtained from someone who knows the patient well, as the patient’s own account may be inaccurate.

The history should cover the patient’s life experiences, assess function, enquire about mood symptoms, unusual ideas or challenging behaviours, and take note of possible causes of dementia, as well as recording personal and family psychiatric history.

One must distinguish between cognitive changes that develop slowly, due to dementia, and those that develop acutely because of delirium. Since delirium, when it occurs, is more often than not superimposed on dementia, it is vital to enquire about recent changes in physical health or medication use.

Mental state examination

People with advanced dementia who live alone often look neglected, but those living with a relative may be neat and well nourished. Patients often conceal cognitive deficits for long periods. Given the high likelihood of dementia being complicated by delirium, it is important to note evidence of physical illness and gauge the capacity to sustain attention. Patients with uncomplicated mild to moderate dementia can attend to questions. Patients with delirium look unwell, are either hyperaroused or drowsy, and are easily distracted.

Disorientation to time is common. Orientation to place is usually well preserved when patients have lived in the same home for years.

Demands that exceed a patient’s capacity to cope may lead to anxiety, agitation and even extreme emotional disturbance. Up to 5% of people with dementia have a major depressive disorder and many more have milder depressive symptoms. Social withdrawal, agitation, tearfulness, insomnia and anorexia suggest comorbid depression.

Language abnormalities range from word-finding difficulty to aphasia. Thinking becomes repetitive and simple. Up to half of all dementias are accompanied by misinterpretations, delusions and hallucinations for at least some portion of the illness. Loss of insight is evident early. Many patients insist that they are coping well when they are not.

Cognitive testing

Cognitive testing is essential. Mildly affected articulate people hide their deficits easily. Short instruments like the mini-mental state examination (MMSE) are useful. Screening tests should not be used to make a diagnosis without additional information, as a poor performance may be due to deafness, poor vision, depression, lack of cooperation, lack of fluency in English or limited education. Such tests provide little information on frontal lobe function and are insensitive in people of above average intelligence with early dementia. Test scores should be interpreted in the light of other information obtained from the patient and informants.

Physical examination and investigations

Physical examination and selected investigations must be performed. Dementia is rarely reversible, but subdural haematomas, cerebral tumours and ‘normal pressure’ hydrocephalus must be excluded, as must anaemia, diabetes mellitus, hypothyroidism, vitamin B12 deficiency and drug toxicity. Standard investigations include a full blood count, erythrocyte sedimentation rate (ESR), glucose, urea and electrolytes, thyroid function and urine microscopy and culture.Others (e.g. folate, vitamin B12, liver function tests, syphilis and HIV serology) may be indicated.

Structural brain imaging has a high yield in the detection of treatable neurological diseases when dementia presents with a history of less than one year’s duration, focal neurological signs are present, symptoms are not typical of Alzheimer’s disease, or the patient is aged less than 65; but has a low yield in other circumstances.

Management

Medical issues

Tasks include establishing a diagnosis of dementia and its most likely aetiology, excluding treatable causes including depression and delirium as sole or contributing precipitants of confusion, and ensuring optimal physical health. The latter is important because patients with dementia often forget to mention symptoms, fail to attend appointments for investigations, and do not take medications reliably. Incidental physical pathology is common, so doctors should look for it. Attention should be paid to the effects of the dementia or other mental disorder on the family member(s) who care(s) for the affected person. Many carers are anxious, depressed or grieving, and may experience ‘carer burnout’.

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