Age is the main risk factor for the development of dementia, with prevalence increasing 20-fold between the ages of 65 and 85 years.¹ Onset below the age of 65 is uncommon, although the condition needs to be borne in mind where there is a strong family history or the patient is vulnerable because of risk factors. Alzheimer's disease is the most common form of dementia, even under the age of 65. Vascular dementia, although uncommon in a pure form, often coexists with Alzheimer's disease - so-called 'mixed' dementia - and is probably overrepresented among older people who require admission to general hospitals.

Investigation

The key 'investigation' in suspected cases of dementia is a good history. When dealing with a complex illness such as dementia, more than one appointment may be required. Although late-onset subjective impairment of memory is a core feature and key risk factor for many types of dementia, it is not in itself diagnostic, nor is carer concern, even though such concern undoubtedly raises the chance of a dementing illness being found.

Of more relevance are deterioration in day-to-day function, changes in social behaviour and changes in personality, or problems with employment if this is relevant. Without such changes a diagnosis of dementia should not be made.²

Changes in day-to-day function might include difficulty in using the telephone, doing the shopping or managing medication, money or planning and executing a journey alone. Tactful questioning regarding driving ability should be included in the assessment if this is relevant.

Changes in social behaviour would include apathy, lack of motivation and withdrawal from the usual social circle. A patient with mild dementia may become less keen to attend social functions or participate in previous sporting activities. Changes in personality may include increasing irritability or behaving inappropriately in company.

Few people with dementia are able to work full time without someone noticing a change in performance.

Spending time exploring intellectual, functional and social change and conducting a brief intellectual assessment may well save the patient unnecessary attendances at secondary care clinics, which can be distressing. Scales such as the Mini-Mental State Examination (MMSE)³ , copies of which can be obtained from your local old age psychiatry service, or the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE)⁴ (see table 1, attached) may be useful. Although the IQCODE suggests examining change over 10 years, it is particularly valuable to assess change over the past year.

Identification of physical and mental comorbidity is important. Depression and anxiety are not uncommon and may exaggerate apparent, intellectual, social or personality difficulties. Undue suspicion may be apparent and/or hallucinations may appear. Visual hallucinations are usually more common than auditory hallucinations and are characteristically mute.

Physical comorbidity may include risk factors for vascular disease, such as diabetes or hypertension, and alcohol misuse, or degenerative neurological diseases such as Parkinson's disease or Huntington's chorea.

Focal neurological symptoms or signs may be present, but symptoms of significant cerebrovascular disease may be limited to headache, dizziness and nausea, urinary frequency, urgency or even incontinence in the absence of abnormalities in urinalysis, persisting low-grade depression or gait disturbances and falls.⁵

Identification of potential contraindications to treatment with cholinesterase inhibitors is also important. These include significant comorbid vascular problems, COPD, prostatic symptoms, or active peptic ulceration. Those with significant bradycardia are another group where the risks and benefits of treatment need to be weighed up carefully.

Laboratory tests should be conducted depending upon indications in individual patients. A full blood count including MCV can be valuable, and LFTs may be abnormal if alcohol misuse is suspected. Serum vitamin B₁₂ and folate levels are seldom done routinely. Syphilis serology is rarely productive in the absence of clear risk. Treatment of any detected comorbidity rarely resolves an underlying dementia, although it may improve physical health and day-to-day function.

Direct access to neuroimaging by GPs is currently uncommon. However, as preparation for referral to secondary care, patients can be advised that they are likely to be offered structural imaging, which would assess vascular change as well as atrophy.⁶ The use of MRI is becoming more common, but is less tolerable to some patients with dementia because of the noise and duration of the examination.

Who should be referred?

Most psychiatric services are not set up to provide detailed memory assessment, but to try to diagnose dementia at as early a stage as clinically possible. Consequently, those patients with evidence of impairment of function, social behaviour, personality or employment in addition to memory difficulties should be considered for referral.

Obvious biochemical abnormalities or comorbid physical conditions should be treated before referral is made. Patients with atypical presentations such as significant behaviour change or change in social function despite apparently intact memory function should also be referred, as a number of these patients, especially those under the age of 65, may have frontotemporal dementia.

While some patients need detailed neuropsychological testing, this can be very complicated and time consuming and is probably best kept for those in whom the diagnosis is in doubt, or where a specific problem, such as a visuospatial deficit, seems to dominate the picture.

Confidentiality

Patients with dementia are entitled to confidentiality, as with any other patient group. Under the principles of the Mental Capacity Act (Adults with Incapacity Act in Scotland), patients are assumed to have the capacity to make decisions about their care and treatment unless shown otherwise. Consequently, it is unrealistic to attempt too much subterfuge in undertaking assessments.

Patients realise quite quickly that memory is being tested and should be advised of this beforehand. Telling a patient that they are being referred to a clinic to investigate their pain, their diabetes or their eyesight is unlikely to be helpful to either the patient or the psychiatrist when they arrive at the specialist clinic.

If approached by third parties such as relatives, it is appropriate to note their concerns, attaching to the record that the information has been obtained from third parties and consequently should not be disclosed to the patient. In turn, however, the relatives should be given general advice about the initial symptoms of dementia, partly because they may be overestimating the problems of the potential patient and drawing inappropriate conclusions, or alternatively they may be able to use the information in a logical fashion to persuade the patient to attend for consultation.

If the patient denies the problem

Although patients may lack insight into the extent and severity of intellectual or functional deficits, they may well be aware of problems to some degree. Tactful exploration often opens the way to further discussion of problems and potential referral. Continuous absolute denial of problems is uncommon, particularly in the face of increasing evidence from carers or other sources.

Some patients deny having problems because they are afraid of the possible diagnosis and may have exaggerated ideas about the rate of decline. Others may expressly state that they would not wish to know of a diagnosis of dementia and consequently refuse further investigation. In these cases it is important that the views of the patient and the carer are in agreement. Carer objections to referral for specialist investigation and potential diagnosis need to be handled sensitively. The carer must realise that there are potential problems ahead, which can be predicted and averted, and that early intervention can prevent future crises arising. Treatment is available for some types of dementia and can be noticeably helpful in around 50 per cent of those who commence therapy.

In some cases the patient simply lacks insight, particularly where there are significant problems in frontal lobe function. Nevertheless, some of these patients may still accept referral, believing either that their 'normality' will be identified or that someone else will be shown to have the problems, for example their spouse.

However, there are some patients who truly deny symptoms and will not tolerate any intervention. In these cases, the patient's carer may in fact be seen as a 'patient' in their own right. A visit from a psychiatric nurse to the couple's home may provide a setting in which the carer's needs can be addressed in an environment in which the problems can be discussed openly. Where someone with capacity rejects involvement, however, their wishes must be respected.

Where capacity is lacking, and particularly when risks are high, practitioners need to consider making a referral without the patient's consent. This might include informing the DVLA of driving risk. The patient's behaviour may be such that the use of mental health legislation becomes appropriate.

Where possible, efforts should be made to identify a power of attorney and/or welfare guardian (or equivalent) and ask those people to take decisions on the patient's behalf.

Treatment of dementia

Cholinesterase inhibitors

The cholinesterase inhibitors donepezil, rivastigmine and galantamine are effective first-line treatments for Alzheimer's disease.

In the UK some degree of cerebrovascular disease as comorbidity is not unusual, and these drugs can still be effective although side-effects such as dizziness, nausea, vomiting and urinary dysfunction may become more frequent. In general, however, side-effects are mild and transient. Long-term use appears to be safe, although some patients have developed problematic bradycardia. For these patients permanent cardiac pacing may allow them to continue treatment with cholinesterase inhibitors.

Although current NICE guidance⁷ recommends restriction of treatment to patients with Alzheimer's disease who have an MMSE between 10 and 20, care must be taken in interpreting this rigidly.

The MMSE was not designed as an instrument to diagnose dementia, nor was its purpose that of following up people taking medication. The MMSE takes no account of function, behaviour, personality or employment changes and all these domains need to be taken into account before deciding the true severity of the patient's dementia.

Similarly, at the lower end of the MMSE score as defined by NICE guidance, scoring is heavily influenced by language difficulties, which are almost universal at this level of dementia severity. Once again function and behaviour need to be taken into account in the decision to discontinue or maintain medication.

There are no real evidence-based alternatives to cholinesterase inhibitors for people with mild dementia. Cognitive stimulation and reality orientation show some promise although the numbers in studies are small.⁸ Results from studies of Ginkgo biloba and Salvia officinalis are inconsistent.^9,10 These compounds are not free from interaction with other medications and patients need to be warned of this possibility.

Currently, people diagnosed with vascular dementia normally have their need for cardiovascular and cerebrovascular protective agents, such as aspirin, ACE inhibitors and statins, reviewed. However, there have been very few studies of the efficacy of these compounds in patients with established dementia and currently there is no good evidence to inform practitioners of the benefits of any individual vascular intervention.

There is some evidence for the effectiveness of cholinesterase inhibitors in dementia associated with Parkinson's disease¹¹ and in the treatment of dementia with Lewy bodies,¹² where the reduction in visual hallucinations may be particularly dramatic.

Antipsychotics

As dementia progresses, behavioural and psychological problems may become more evident. Patients with these problems are often very distressed and many welcome the offer of treatment if insight is retained. In other cases it is important to work with the family and/or carers to try to identify the antecedents of behavioural problems and reduce the impact of their consequences. Community psychiatric nursing can be very valuable here.

In many cases, however, the careful use of medication brings valuable results.

Currently, atypical antipsychotic drugs such as risperidone and olanzapine are not recommended for use in people with dementia because of concerns about cerebrovascular adverse events, including stroke. However, the incidence of these problems associated with conventional antipsychotic treatment is not clear, and stroke risk is not associated solely with treatment but with many other factors.

Consequently, some patients may still receive atypical antipsychotic treatment after discussion with the patient, their family and carers about the risks involved.

Antidepressants

Antidepressants can be effective although antidepressant response may take longer in someone with dementia than in a cognitively intact patient. Response may be limited in range. There is little evidence to support the use of one type of antidepressant over another, although few people would prescribe an older tricyclic such as amitriptyline or imipramine for someone with dementia because of their anticholinergic activity and potential effects on blood pressure and falling.

A selective serotonin re-uptake inhibitor (SSRI) or an agent such as mirtazapine can be appropriate.

Non-pharmacological agents

Evidence for the effectiveness of non-pharmacological treatments, such as aromatherapy and multisensory stimulation, for behavioural problems tends to be restricted to those with severe dementia, and overall is not particularly convincing because of low numbers and other methodological limitations of clinical studies.

Conclusion

Dementia is becoming increasingly common in the UK population. The presenting features comprise not only memory problems but also difficulties in day-to-day function and changes in social behaviour, personality or employment performance. The identification of comorbid problems such as depression and anxiety, hypothyroidism or alcohol misuse, Parkinson's disease and Huntington's chorea are all worthwhile. Most patients are aware of their problems, although not necessarily their true extent or severity.

Referral to secondary care services should be considered for those with evidence of impairment in areas in addition to memory or where the presentation seems atypical. Cholinesterase inhibitors are effective in a number of cases and the decision to initiate or discontinue treatment needs to take account of a range of factors, not simply a score on a cognitive test.