Dementia is a chronic progressive mental disorder that adversely affects higher cortical functions including memory, thinking, orientation, comprehension, calculation, learning capacity, language and judgement. Alzheimer's disease is the most common form of dementia. It is a degenerative cerebral disease with characteristic neuropathological and neurochemical features.
Population data from 2005 indicate that 380,000 people have Alzheimer's disease in England and Wales. The UK incidence of Alzheimer's disease in people over the age of 65 years is estimated to be 4.9 per 1,000 person-years. Between 50 and 64% of people with Alzheimer's disease are estimated to have mild to moderately severe disease, and approximately 50% have moderately severe to severe disease.
Alzheimer's disease is usually insidious in onset and develops slowly but steadily over several years. It predominantly affects older people. The median survival for people with Alzheimer's disease from onset has been estimated at 7 years, although survival figures vary and depend on how they are measured, comorbidities, age (median survival decreases with increasing age) and sex.
Progression is characterised by deterioration in cognition (for example, thinking, conceiving and reasoning), functional ability (for example, activities of daily living such as dressing, personal hygiene and handling money), behaviour (for example, agitation, wandering and uncharacteristic aggression) and non-cognitive symptoms including depression, delusions and hallucinations. People with Alzheimer's disease might find it increasingly difficult to do everyday activities, such as shopping, socialising and recognising people and places. Communication may become a problem as people find it more difficult to find words and remember names. In later stages of disease, physical problems can include problems with eating, swallowing, incontinence, and unsettled and unsettling behaviour. Alzheimer's disease may also be associated with loss of confidence and feelings of fear, confusion, apathy, stigma and depression. The effects of Alzheimer's disease are heterogeneous and vary from patient to patient.
Alzheimer's disease has many impacts including physical, mental, nursing, medical and social impacts. Carers (including friends and family) are affected by the progressive deterioration in cognition, function and behaviour of a person with Alzheimer's disease. Behavioural symptoms can have a particular impact on carers, and are often the reason cited for a person with Alzheimer's disease going into full-time residential care. Alzheimer's disease can have a profound and far-reaching effect on family and carers as well as the patient including institutionalisation and a financial impact on family, carers and the state.
The severity of Alzheimer's disease can be assessed using several methods, depending on the setting (for example research or clinical practice) and the outcome being assessed. Clinical practice uses a variety of measures, often along with clinically based assessments such as biographical interview. Severity is frequently defined by Mini Mental State Examination (MMSE) score:
mild Alzheimer's disease: MMSE 21 to 26
moderate Alzheimer's disease: MMSE 10 to 20
moderately severe Alzheimer's disease: MMSE 10 to 14
severe Alzheimer's disease: MMSE less than 10.
The aims of treatment are to promote independence, maintain function and treat symptoms including cognitive, non-cognitive (hallucinations, delusions, anxiety, marked agitation and associated aggressive behaviour), behavioural and psychological symptoms.
There is no cure for Alzheimer's disease. Current management involves the treatment of cognitive, non-cognitive and behavioural symptoms. AChE inhibitors (donepezil, galantamine and rivastigmine) and memantine are the pharmacological treatments available specifically for Alzheimer's disease. Non-pharmacological treatment includes social support, increasing assistance with day-to-day activities, information and education, carer support groups, community dementia teams, home nursing and personal care, community services such as meals-on-wheels, befriending services, day centres, respite care and care homes.