This section explores general issues in diagnosis, demography and the prevalence of dementia. Demographic factors influencing the prevalence of dementia in Cumbria and South Lakeland are explored. Important demographic and social trends relevant to prevalence of dementia and future service provision in the area are discussed.

Dementia is a syndrome, a set of characteristic symptoms caused by a variety of known and unknown disease processes of the brain. Dementia is usually chronic, progressive and, except when resulting from brain injury or stroke, of slow onset. Typically, people with dementia experience a range of symptoms such as:

• decline in short term memory
• anxiety
• personality change
• lack of interest and withdrawal from normal activities
• decline in ability to perform everyday tasks
• difficulty finding and using words
• repetitive conversation

It is important to distinguish between dementia and mental confusion or delirium. Many forms of dementia are progressive and irreversible but confusional states are often the result of underlying medical conditions such as pneumonia, urinary infection, depression, drug reactions and physical or mental stress. Identifying and treating the underlying cause of delirium can often alleviate confusion. In frail elderly people delirium can also occur as a result of dehydration, constipation, impaired vision or hearing and environmental changes. People with dementia can also suffer additional confusion and disorientation as a result of these conditions beyond that resulting from their dementia. Care must be taken when assessing the mental state of people with dementia to exclude the possibility of treatable delirium.

A significant minority of permanent, non-progressive dementia cases are the result of cerebro-vascular disease. A recent study of 337 stroke patients found 31.8% of patients suffered dementia as a consequence of Cerebro-Vascular Accident [Stroke]. Distinguishing between stroke dementia and progressive dementias, such as Alzheimer’s disease, is crucial in providing effective and appropriate care for people with dementia. Alzheimer's dementia is a progressive and, as yet, irreversible condition but further deterioration of cognitive abilities in stroke dementia patients can be prevented by action to reduce the risk of further strokes. Attention to predisposing lifestyle and biological factors in stroke dementia needs to be prioritised in medical and social care responses. (Pohjasvaara, Erkinjuntti et.al. 1998) Health and social care services can help to reduce the risk of further deterioration in stroke dementia cases by focusing on interventions that reduce the risk of further strokes and inform about predisposing lifestyle factors such as stress, diet and exercise.

Alzheimer's disease is the primary cause of dementia in older people, although less than one third of all cases of early onset dementia (under 65 yrs.) are the result of Alzheimer's Disease (Harvey, 1998). Definitive diagnosis of Alzheimer's dementia can be confirmed only at autopsy and, in clinical practice, the accuracy of diagnosis largely depends on the experience and judgement of the examining doctor. Diagnosis, especially in the early stages of dementia, is complex and uncertain requiring a systematic evaluation of signs and symptoms against all possible diagnoses until the most probable diagnosis can been identified. This process is known as 'differential diagnosis'. Accurate medical diagnosis is critical from the outset and a rigorous approach to differential diagnosis is particularly important in dementia as clinical prognosis varies according to the underlying cause of the dementia. Doctors may choose from a range of diagnostic criteria that have been developed by various medical bodies to aid diagnosis. Two commonly used diagnostic sets are summarised below.

(Diagnostic and Statistical Manual of the American Psychiatric Association. 4^th edition)

Source: Villareal, T and Morris, J.C. (1998) The Diagnosis of Alzheimer's Disease Alzheimer's Disease Review 3 142-152

(International Classification of Diseases 10th Edition)

Source: Villareal, T and Morris, J.C. (1998) The Diagnosis of Alzheimer's Disease Alzheimer's Disease Review 3 142-152

General Practitioners (GPs) are divided in their willingness to accept the validity of some diagnostic sets. Costigliola's (1997) study of more than 1,000 European family doctors found that only half of the GPs were convinced of the validity of the DSM criteria for dementia. Others preferred to use different diagnostic criteria. Some doctors claim a high degree of accuracy in diagnosis of dementia but with differing diagnostic criteria and a lack of consensus amongst doctors about the validity of diagnostic sets these claims must be treated with some caution. A recent Canadian study (Erikinjuntti & Østbye, et.al. 1997) casts doubt on the coherence of a variety of common diagnostic sets. The study reviewed clinical diagnoses of dementia in 1,879 cases. The researchers applied six commonly used diagnostic sets for dementia to the cases and found a wide variation in diagnosis of dementia according to the diagnostic set applied. Diagnosis of dementia using ICD-10 criteria produced a diagnosis of dementia in 3.1% of cases. Application of DSM-III criteria produced a diagnosis of dementia in 29.1% of cases. Only 20 of the 1,879 cases were given a diagnosis of dementia by all six of the diagnostic sets tested. Variations in diagnosis were more marked in early stage dementia.

Diagnosis is often most contestable in cases of mild to moderate dementia. Mild dementia involves some cognitive impairment but may result in little interference with daily living. It is possible that some cases of mild dementia are the result of undiagnosed conditions such as low-grade cerebro vascular disease or psychiatric disorder. In these cases there may be little impact on daily living whereas other mild dementias are in fact early stage dementia. With diagnosis of mild dementia so uncertain some demographic studies exclude these cases. As a result some prevalence studies may underestimate the actual number of cases of dementia within a community.

Demographic studies of dementia can indicate the likely numbers, or prevalence, of dementia cases in a community. They provide a valuable starting point for planning local services but, like all statistical studies, their usefulness is dependent on the validity and reliability of the methodological tools utilised in the study. Direct comparison of dementia prevalence studies is complicated because individual studies often apply different criteria for diagnosis, are variable in the thoroughness of case finding and apply differing definitions of severity for case inclusion.

It is also difficult to assess the actual number of cases of dementia within a population because the onset of some dementias, such as Alzheimer's, is insidious and symptoms for conditions such as depression, stroke and other brain injuries may have similar presenting signs. In addition people with dementia may not attend for medical examination until some time after the onset of symptoms. Demographic studies have therefore derived dementia prevalence rates by comparison of actual cases found and other demographic studies. Although not entirely accurate prevalence rates give a good indication of the total number of cases of dementia expected given the size and structure of a population. Prevalence rates vary from study to study, partly due to differences in research methodology and difficulties in diagnosis of 'mild' or marginal dementia. But the major studies (Hofman, Rocca et.al, 1991 and Jorm, Korten, et al. 1987) are generally agreed to provide a reliable basis for local prevalence estimates. These studies show a clear relationship between age and the prevalence of dementia. The tables below illustrate this relationship.

Source: Hofman et al. 1991

Source Harvey (1998)

The significance of age is reinforced by Carr's (1992) survey of dementia cases in Tayside. The Tayside study found that 55% of dementia sufferers were aged over 80 yrs. and 30% were aged between 70-80 yrs. Only 4% of people with dementia in Tayside were under 60 yrs. Almost two thirds of dementia sufferers are women although this is mostly accounted for by the gender structure of the older population. While the risk of dementia increases markedly with age only a very small minority of people over 65 have dementia. In the Tayside study only 6.9% of all residents over 65 had dementia.

The majority of cases of dementia are found in people over 65 but a small percentage of cases occur in younger age groups. The terms 'young onset' and 'early onset' dementia are normally applied to these cases. It is important to clarify the difference between the Early onset and early stage dementia. Early onset dementia refers to the onset of dementia before the age of 65. Early stage dementia refers to the degree of impairment or the nature of the clinical signs present in an individual with progressive dementia. Early stage dementia can apply to individuals in any age group who are in the early stages of progressive dementia.

Differences in clinical signs and prognosis between early onset and late onset Alzheimer's remain contentious. (Harvey 1998) Some studies suggest that symptoms are more severe and deterioration is more rapid amongst younger onset sufferers but others have failed to find statistically significant differences. Differences between the clinical, pathological and biochemical features of early and late onset Alzheimer's groups has not been shown to be statistically significant. Recent genetic discoveries suggest that the differences between early and late onset Alzheimer’s disease are probably the result of genetic influences and sporadic forms of Alzheimer's disease.

Harvey’s (1998) study of young onset dementia in the London area, found 67.2 cases per 100,000 amongst the 30-64 age group suggesting a total of 16,737 cases throughout the UK. Alzheimer's disease accounted for less than one third of all younger dementia cases with the majority of dementia’s resulting from other conditions such as vascular disease, traumatic brain injury, alcohol and drug related conditions.

Table 3 shows the estimated numbers of young onset dementia cases predicted for the UK based on current population and prevalence rates.

Source: Harvey, R. J. (1998)

Approximately 5,500 people under 64 years of age in the UK have Alzheimer's type dementia, representing less than one third of all dementia cases in the younger age group. (Harvey, 1998)

South Lakeland is a popular location for older people wishing to retire. Consequently the number of older people in the local population is much higher than the national average. With the prevalence studies suggesting the rate of dementia roughly doubling every five years after the age of 65, local demographic trends present a major challenge to the future of dementia care services in South Lakeland.

South Lakeland's popularity with people at or near retirement age will continue to influence the nature of health and social care demands in the 21^st Century. More than 46% of South Lakeland’s current population are over 45 and almost 21% are over 65. (Morecambe Bay Health Authority, 1996) Over the next twenty years most of these people will move into the higher risk age bands for dementia and other age related conditions. South Lakeland also has the highest proportion of older people in Cumbria with almost 25% of all Cumbrian residents over 65 living in the South Lakeland district. Consequently 1 in 4 of all Cumbrian cases of dementia are likely to be found in South Lakeland.

Prevalence rates for Cumbria and South Lakeland have been calculated and are presented below using both Hofman (1991) and Alzheimer’s Society UK (1998) rates for comparison. Differences in the total number of male and female cases after 65 yrs are in line with the gender profile of the local population. (Office for National Statistics 1996)

Table compiled from: Hofman & Rocca, et al (1991) Alzheimer's Disease Society (UK 1998) and Office for National Statistics (1996)

Table compiled from: Hofman & Rocca, et al (1991) Alzheimer's Disease Society (UK 1998) and Office for National Statistics (1996)

Prevalence estimates differ about the numbers of younger onset cases, but even Hofman's higher rate suggests that there are likely to be relatively few men and women with early onset dementia in the South Lakeland area and for Cumbria as a whole the numbers remain relatively small. This does not preclude the possible need for a countywide response to age appropriate care support for younger people with dementia.

A closer examination of population distribution within South Lakeland gives an indication of the prevalence of dementia in each electoral division. Differences between divisions are influenced by the population age structure in each area and particularly by the numbers of people over 75.

Derived from: Cumbria County Council Population Estimates 1997 & Alzheimer's Disease Society Prevalence Rates 1998.

Numbers have been rounded up for clarity

Although these figures give us a reasonable idea of the situation at present we also need to take into account the potential impact on prevalence rates of future demographic trends. Population projections for England and Wales forecast a 138% increase in the number of people over 85 yrs. by 2031. (OPCS Monitor 1994) On a national level this is likely to result in a significant increase in the number of cases of dementia. Local demographic trends indicate particular problems in South Lakeland. Population data for the period 1985-1995 reveal that the numbers of very elderly people (85+) in South Lakeland increased by 63%. (Morecambe Bay Health Authority, 1994) If this growth in population is repeated during the next ten year period the expected number of cases among the over 85’s in South Lakeland alone would rise to 978. A rise in the number of cases of dementia on this scale would place considerable demands on local health and social care services. Prevalence of dementia rises dramatically amongst the very elderly and with around 3,000 people over 85yrs. in South Lakeland (Morecambe Bay Health Authority, 1996) there are likely to be around 600 cases amongst this age group in the area.

It is almost impossible to ascertain the actual number of people using formal health and care services as only hospital services collect comprehensive data on reasons for referral. South Lakeland social services receive around 150 new referrals to the Adult and Hospital teams each month but age, gender or reasons for referral are not recorded. (Customer Services South Lakeland District Social Services Department 1998) There is no way, short of reviewing confidential case files, of knowing how many of these referrals are related to underlying dementia. Likewise reliable data is not available to indicate numbers of residents in local nursing and residential homes with dementia.

Larger scale studies confirm that most people with dementia are cared for in their own communities. Relatively small proportions of admissions to hospital are for a primary diagnosis of dementia. Hospital admission and discharge data for Westmorland General Hospital show only 91 admissions with a primary or pre-existing diagnosis of dementia for the twelve-month period up to October 1998. (Westmorland General Hospital 1998) Of these only 2 were under 65yrs and 72 were 80yrs or over on admission.

Data is not readily available on GP diagnosis or treatment locally but GP list data provide practice patient age profiles revealing significant proportions of the patient population are over 55yrs in a number of South Lakeland practices. This implies a greater prevalence of dementia within these practices.

Source: Morecambe Bay Health Authority (1998) GP Practice Profiles Unpublished Data

*Practice names are coded for reasons of confidentiality

According to the Office for National Statistics ((June 1999) people are living longer than ever before and, significantly for dementia care, there has been a large increase in the number of people over 80yrs. Around 4,400 people were aged 100yrs or more in 1991 compared with 600 in 1961. By 1997 71% of women aged over 85 in private households were living alone. This growing trend towards single person households, particularly amongst older people, is likely to make provision of community based care more difficult in the near future. (General Household Survey 1997) The main causes of longstanding ill health amongst older people are musculo-skeletal conditions such as arthritis, rheumatism, back problems and other bone and joint problems. (General Household Survey 1997) This can have a significant effect on mobility and independence and is likely to increase the general demand for community support. One in five people aged 45-64 were providing care to someone else in 1995-6 and 9.6% of households where the oldest adult was 75-84 received home care from local authorities in 1997. (Office for National Statistics 1999)

Cumbria County Council recognises that families are becoming more fragmented with an increase in divorce rates and trends towards single parent families and people living alone increasing. These trends will have an impact on the capacity of families to care for dependent older relatives. Almost 30% of Cumbrian residents live alone. (Cumbria County Council 1997) Polarisation of rich and poor groups in the community looks set to increase in the future. Added to this an increased tendency towards 'activism' influenced by rising levels of education and a growth in the proportion of middle class occupations continues to fuel a growth in social expectations. Future generations of older people are likely to be more demanding and better informed than the current generation. This along, with the demographic changes already projected, is likely to increase the pressure on public sector services to meet demands for health and social care support in the community. Improvements in life expectancy in the UK are likely to increase the number of cases of dementia in the elderly population. Areas with a high proportion of older people will almost certainly see a significant rise in the number of cases of dementia in the coming years especially with demographic trends indicating an increase in the population over 80 yrs. Adoption of a more healthy lifestyle amongst middle aged residents aiming to reduce the risk of cerebro-vascular disease would reduce the number of stroke dementia cases in the area.