Dementia

• Associated deterioration in language (aphasia), perception and comprehension (apraxia)
• Impaired ability to recognise objects (agnosia)
• And/or a disturbance in executive functioning (inability to think abstractly and plan, initiate, sequence, monitor and stop complex behaviour)

Deterioration must represent a progressive decline from a previous higher level of functioning, and consciousness should not be clouded (compare to acute confusional state or delirium).

Memory loss is typically for recent events and long-term memory can be remarkably intact.

Incidence

There are an estimated 163,000 new cases of dementia identified each year.¹
It increases with age:

• 6.7% per 1,000 person years at age 65-69.
• 68.5 per 1,000 person years at age 85 and above.¹

Prevalence

Very rare below 55 years. 3% prevalence by 70 years and doubles every 5.1 years thereafter.
According to UK figures provided by the Alzheimer's Society prevalence is:²

• 1:1000 in patients aged 40-65
• 1:50 in 65-70 year olds
• 1:20 in 70-80 year olds
• 1:5 in the 80+ age group

Multi-infarct dementia is much less common nowadays. This is almost certainly because practices are diagnosing hypertension and treating it energetically at an early stage.

In contrast to acute confusional state, which is usually is of recent onset and may have a reversible cause, the history should go back at least several months and usually several years.

Typically the patient has become increasingly forgetful and has carried out the normal tasks of daily living e.g. cooking, shopping with increasing difficulty. Sometimes the patient appears to have changed personality e.g. by becoming uncharacteristically rude and aggressive or be antisocial e.g. sexually disinhibited or shoplifting. They may have hallucinations or delusions, but these are unusual and may suggest a more acute confusional state or Lewy body disease. For objective evidence, carry out a test of cognitive functioning (see below).

Consider Dementia with Lewy bodies (DLB) in elderly patients presenting with hallucinations, lucid periods, movement disorders, falls or syncope. Making this diagnosis will have important implications for treatment (use of neuroleptics in these patients causes 2-3 fold excess mortality).⁵

The diagnosis of dementia should only be made after:

• Comprehensive history and physical examination. The key to diagnosis is a good history of progressive impairment of memory and other cognitive functioning (usually requiring the help of a spouse, relative or friend).
  
  Make specific notes on the following:⁶
  • Attention and concentration ability
  • Orientation - Time, place, person
  • Memory - both short and long term
  • Praxis - can they get dressed, lay a table etc.
  • Language function (usually evident during questioning)
  • Executive function - problem solving etc.
• Conduct a formal screen for cognitive impairment - see separate record.
• Other reversible organic causes have been excluded.

• Ensure no treatable cause has been missed by arranging FBC, ESR or CRP, MSU, U+E, LFT, Glucose, Ca²⁺ , TFT, B12 and folate (red cell folate). Don't always believe low-normal B12s: cellular deficiency may co-exist - if in doubt one should treat (homocysteine metabolites may be a better test).⁸
• Consider blood cultures, CXR and CT/MRI scan, psychometric testing as appropriate to confirm diagnosis.
• VDRL/TPHA should not be performed routinely - only if risk factors are present.
• CSF examination should be used if Creutzfeldt-Jakob disease or other forms of rapidly progressive dementia are suspected.⁹
• Patients with mild cognitive impairment (MCI) should be referred to memory assessment clinics. MCI is defined as a decline in cognitive function greater than expected taking account of the subject's age and education which is not interfering with activities of daily living (ADL).
• Genetic clinical genotype analysis should only be requested where an inherited cause is suspected.⁶

• Refer to a specialist with expertise in differential diagnosis - so that the subtype of dementia can be identified using the appropriate criteria and investigations.
• Nominate a key worker, and agree a mental health care management plan with the principal carer. Record in the patient's record.
  Care plans should address patient's activities of daily living (ADL), particularly trying to maximise their independence. The aim to keep the patient in as familiar and unchanging an environment as possible, building in exercise and occupational therapy, and some flexibility to cope with fluctuating abilities.
• Identify and involve all carers as much as possible and ensure they understand both the diagnosis and prognosis (prepare the spouse for the day when the patient no longer recognises loved ones).
• Try to involve the psychiatric social worker and carer support workers early. They can help with the initial risk assessment, arrange appropriate financial support (allowances etc.); arrange day care, day centre attendance, relief admissions etc..
• Behavioural and psychotic symptoms may need assessment by psychogeriatrician, who may also assess whether drug treatment is appropriate to prevent deterioration.
• Driving is a very complex task and people who are demented must not drive. There may be lack of insight and reluctance to lose mobility and freedom.
• Give any specific treatment and treat concurrent illnesses (these may contribute significantly to confusion).

Acetylcholinesterase inhibitors

There is currently considerable controversy about the treatment of dementia. The Scottish Intercollegiate Network (SIGN) has released guidance, which differs significantly from that of the National Institute for Clinical Excellence (NICE). To summarise NICE recommend that patients with moderate Alzheimer's disease (whose Mini Mental State Examination score is between 10 and 20 points) should be initiated on an acetylcholinesterase inhibitors. Whereas SIGN recommends that acetylcholinesterase inhibitors should be considered for all Alzheimer's patients, irrespective of whether the dementia is mild, moderate or severe. See Alzheimer's disease record for more detail.

• Treatment is started by a doctor who specialises in the care of people with dementia (psychiatrists, neurologists and geriatricians), after appropriate discussion with family and carers.
• These drugs have cholinergic side effects and should be started at a low dose, and then be titrated according to response.
  • The patient should be reviewed every 6 months by MMSE score, global, functional and behavioural assessment by the specialist team or in an agreed shared care arrangement.
  • The views of carers on the patient's condition are discussed at the start of drug treatment and at check-ups.
  • The drug is stopped if the patient's MMSE score falls below 10 points, or if the drug isn't working.
• For people with vascular dementia, acetylcholinesterase inhibitors and memantine should not be prescribed for the treatment of cognitive decline, except as part of properly constructed clinical studies¹⁰.

The three drugs in this class (donepezil, galantamine or rivastigmine) are all licensed for mild to moderate dementia (mini mental state examination (MMSE) score of between 10 and 20). The least expensive of these three drugs is prescribed first. However, if this is not suitable for the patient another drug could be chosen.

• Donepezil is initiated at 5 mg at night and if necessary increased to 10 mg.¹¹
• Galantamine has nicotinic receptor agonist properties as well as being a reversible inhibitor of acetylcholinesterase. The usual dose is initially 4 mg twice daily for 4 weeks increased to 8 mg twice daily for 4 weeks. The maintenance dose is 8-12 mg twice daily.¹²
• Rivastigmine is a reversible non-competitive inhibitor of acetylcholinesterases.¹³ It is initially given at a dose of 1.5 mg twice daily, increasing in steps of 1.5 mg twice daily at intervals of at least 2 weeks according to tolerance and response. The usual range is 3-6 mg twice daily, with a maximum of 6 mg twice daily. The notable gastrointestinal side effects are more common in women than in men.¹⁴

N-methyl-D-aspartate (NMDA) antagonists

Memantine is a N-methyl-D-aspartate (NMDA) antagonist. It is not recommended by NICE except as part of a clinical trial (for moderately severe to severe dementia).^15,16

• Several short-term trials show efficacy of risperidone and olanzapine in reducing the rate of aggression, agitation, and psychosis.
• Alternative treatments include anticonvulsants, such as divalproate and carbamazepine, and short-acting benzodiazepines, such as lorazepam and oxazepam.¹⁷
• The cholinergic deficits can contribute to the development of behavioural symptoms, and treatment with acetylcholinesterase inhibitors also shows improvements in behavioural symptoms.

Patients and relatives with a suspected genetic cause for dementia should be offered genetic counselling by the regional genetic services.

The focus for prevention should be the modification of behaviour in middle aged and older people (reducing smoking, alcohol consumption, obesity and treating other cerebrovascular disease risk factors such as hypertension and hypercholesterolaemia).⁶