Most patients with dementia suffer from Alzheimer's disease (AD), senile dementia of the Alzheimer type, particularly if mixed cases (patients with additional pathological changes) are subsumed under the same diagnosis. This incurable, degenerative, and terminal disease was first described more than 100 years ago, by the German neurologist and psychiatrist Alois Alzheimer,¹ with the now well recognised amyloid plaques and neurofibrillary tangles.

Brains of patients with other types of dementia show a spectrum of different changes such as ubiquitin staining Lewy bodies in 15-20% of cases² and vascular changes in a further 15-20%.³ In life, AD can only be diagnosed as "possible" or "probable AD" ⁴ leaving a degree of uncertainty about the actual underlying pathology.

The list of possible differential diagnoses is long and an accurate diagnosis is often made only after detailed investigation or at post-mortem. An absence of effective prevention and treatment has traditionally encouraged a lack of diagnostic zeal.⁵ The advances made in the basic science of the dementias far outpace those for other mental illnesses; the call for formal memory clinics⁶ comes at a time when such services may soon be able to offer real treatments.⁷

 

How common is AD?

 

Longitudinal cohort studies provide incidence rates of 10-15 per 1,000 person-years for all dementias and 5-8 per 1,000 person-years for AD.^8,9

Advancing age is an incremental risk factor for the disease: every five years after the age of 65, the risk of acquiring the disease doubles, increasing from 3 to as high as 69 per 1,000 person-years.¹⁰ Women, particularly those older than 85, have a higher risk of developing AD.¹¹ There are a number of reasons for this, including gender specific survival rates, but also apparently X-chromosome linked inheritance.¹²

There are 700,000 people with dementia in the UK today, a number forecast to double within a generation.³ There are 163,000 new cases of dementia in England and Wales each year - one every 3.2 minutes.¹³ Each year 39,400 more people are diagnosed with AD in England and Wales. That equates to one new case every 13 minutes.¹⁴

 

Diagnosis

As it is so common, AD often goes unrecognised or is misdiagnosed in its early stages. Healthcare professionals, patients, and family members often mistakenly view early symptoms of AD as the inevitable consequences of ageing.

 

Some disorders that can result in dementia, such as major depression, poor nutrition, and drug interactions, are curable, but AD is not. It is therefore important to diagnose the cause of the dementia early and correctly. Certain symptoms associated with AD, such as incontinence and depressive symptoms, can be effectively treated, and should be identified as soon as possible.

The history taken from the patient and relatives will help to clarify most aspects of past and current health. Medical problems need to be actively identified, a plan of treatment developed, and the patient's health monitored over time.

Patients should also undergo blood tests to screen for changes in blood count, electrolytes, glucose, vitamin B₁₂, folate, thyroid, renal and liver function, and VDRL. Blood pressure should be checked and a short neurological examination performed. Ideally, a structural scan (CT or MRI) should be arranged to exclude organic treatable processes.

The routine use of dementia screening instruments may increase detection rates.The Mini Mental State Examination (MMSE)¹⁵ is the most commonly used screening test for dementia, and has recently even been enlisted to determine which patients should receive certain treatments.^3,16 The MMSE covers the domains of orientation, registration, attention and calculation, recall, language, writing, executive function and praxis.

The rationale for this test is broadly to tap into complex associated cortex functions that may be affected in dementia. The test takes only about 10 minutes, but is limited by its inability to detect more subtle cognitive impairment, especially in patients with previous high educational achievement. Conversely, patients from linguistic minority groups, patients with low educational attainment or intelligence may score poorly in the absence of cognitive deterioration¹⁷ and someone with high educational attainment may score well despite having clinically evident cognitive impairment.¹⁸

The rule of thumb for the separation into normal (25-30), mild (20-25), moderate (10-20) and severe (16

 

Evidence-based treatment

Treatments have to be separated into those targeted at cognitive impairment, such as memory loss, and treatments for behavioural changes, such as agitation and challenging behaviour. Treatment guidelines published by NICE in 2007 have been complemented by a recently updated technology appraisal on donepezil, galantamine, rivastigmine, and memantine.^3,16

 

"People with dementia who develop non-cognitive symptoms or behaviour that challenges should be offered a pharmacological intervention in the first instance only if they are severely distressed or there is an immediate risk of harm to the person or others," the NICE guidance states.³ Further, AChEI are recommended in AD after considering antipsychotics. The latter should be avoided in dementia with Lewy bodies (DLB), as antipsychotics can cause serious complications in this patient group.² In vascular dementia, AChEI are not recommended.

The pharmacological treatment of behavioural symptoms of dementia, including depression, should be initiated by specialists.³ Even in their hands, however, the inability to allocate patients unambiguously to one diagnostic group will make it necessary to use careful clinical judgement when implementing the guidelines.

The tendency for evidence to be available only for relatively pure (probable) diagnoses, and otherwise relatively healthy patients, would exclude a substantial group of patients from being offered interventions. An open and honest discussion of the limits of evidence with patients and their family tends to help arrive at a valid and effective treatment contract.

 

Referral

While the NHS awaits the establishment of new specialist services to deliver "good quality early diagnosis and intervention to all patients" with dementia⁶ many of the expected services may fall to general practice to deliver.⁵ At present, there are three groups of patients that GPs can refer to specialist care:
• Patients eligible for treatment with AChEI.^3,16
• Patients whose diagnosis is unclear and who may need more specific investigations, such as brain scans or neurological and neuropsychological examinations
• Patients who may benefit from a combined approach with psychotropic drugs and behavioural support from a mental health team in the community.

 

Referral to occupational therapy for cognitive stimulation programmes may be helpful.This means that patients with subjective or objective memory impairment, but without functional deterioration (so called mild cognitive deterioration), who are not included in this list, are currently dependent on the availability of local memory clinics.^6,19-22

 

Supporting sufferers and their families

Members of the primary healthcare team can help patients to remember to attend for their clinic appointments by providing memory aids in their home or by sending out direct reminders.

 

The GP, who is at the hub of many services, and who acts as the patient's advocate, as well as controlling access to scarce resources, needs to be well informed about local services.

Primary care has a significant role to play in educating the public about dementia, its consequences, and the therapeutic and preventive measures that are available. GPs should not only liaise with mental health trusts and aim for collaborative care of elderly demented patients, but also with health planners and administrators in PCTs so that adequate attention is given to dementia services. While one of the central tenets of the National Dementia Strategy appears to be the establishment of specialist memory clinics, a compromise situation may arise where services that can easily be accommodated in primary care are left in this setting.

Health visitors and practice nurses with specialist training could carry out cognitive screening, behavioural assessments and liaison with carers and residential homes. GPs could take over pharmacotherapy in shared care arrangements, particularly in more remote areas. Some GPs have been successful in running their own continuing care and assessment units for demented patients in rural areas.²³