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6 Interventions in Alzheimer’s Disease KCE Reports 111
1.1.2 Some epidemiological data
In 2005, the proportion of people with dementia in the European Union was estimated
at 1.14% to 1.27% of the population. For Belgium the estimate was 1.22% to 1.35%,
corresponding to 127 174 and 140 639 subjects.(www.dementia-in-europe.eu, consulted
May 14, 2008). The number of AD patients in Belgium is not well documented but can
be estimated at about 75 000 patients in 2008 (presentation Prof Patrick Santens,
Ghent, 2008). This corresponds to about 55% of all dementia patients.
The published prevalence of dementia ranges from 6.3% to 9.3% for subjects 65 years of
age and older. About one in three persons aged 90 years and older has dementia. A
Belgian study based on GP consultations reported a prevalence of 11% in subjects 65
and older, living at home. 2 The prevalence varies strongly with the study context: from a
prevalence of dementia diagnosed by a GP of 2% in subjects 60 years and older, to
44.1% to 47% for institutionalized subjects over 60 years of age. 3 About two thirds of
the dementia patients in Belgium are women, mainly because the life expectancy is
higher for women than men, but also because of a somewhat higher incidence in elderly
women. The average life expectancy after diagnosis of AD is 5 to 6 years, or 8 years
after the first symptoms. Life expectancy depends on the age at the moment of the
diagnosis: as high as 10.7 years for the youngest patients (65-69 years) to a low of 3.8
years for the oldest (90 or older at diagnosis). Roughly, this is about half of the life
expectancy of a person with the same age but without AD. In the Walloon region, it is
estimated that 60% of patients diagnosed with dementia are cared for at home and 40%
in institutions.(Dementia in Europe, Yearbook 2007, www.dementia-in-europe.eu). In
Flanders 48% of the patients in institutions are scored as patient with dementia (KCE
Report 47). In Belgium institutionalisation capacity is 127 365 beds (ROB, Rustoord
voor Bejaarden, and RVT, Rust- en Verzorgingstehuis – MR, Maison de Repos and MRS,
Maison de Repos et de Soins beds in 2008, RIZIV/INAMI) This would mean that of the
75 000 patients with AD in Belgium, about 34 000 AD patients are institutionalized and
41 000 AD patients are cared for at home.
1.1.3 Pathophysiology and symptoms
Clinical AD is preceded a by slowly progressing accumulation in the brain of amyloid
plaques and neurofibrillary tangles with hyperphosporylated tau protein. Memory
impairment is usually one of the first characteristics of AD. As the disease progresses
cognitive deficits start to interfere with usual activities. The predemential phase of AD,
characterized by relatively isolated memory impairment in patients that are still
autonomous, was labelled as “mild cognitive impairment” (MCI). The proportion of MCI
patients who evolve to overt AD varies by study setting and is about 5-10% per year. 4
This new entity became a major field of research in recent years, in an effort to
establish the diagnosis of AD at an earlier stage. It is expected that earlier intervention
with future disease-modifying therapies will be more effective than current symptomatic
therapies, indicating that an early accurate diagnosis will become even more important.
Clinically significant neuropsychiatric symptoms, named and grouped as BPSD
(Behavioral and Psychological Signs and Symptoms of dementia), are found in about onethird
of dementia patients with mild impairment and in two-thirds of those with more
severe impairment. 5 These proportions are even higher in dementia patients in
residential care. Neuropsychiatric symptoms contribute significantly to caregiver
burden, institutionalization, and decreased quality of life for patients with dementia.
Several different methods are used to assess the severity of Alzheimer’s disease but the
most frequently used test for this purpose is the Mini Mental State Exam (MMSE). 6 The
MMSE (a 30 point scale) denotes the severity of cognitive impairment as follows (cut-off
values may differ slightly according to the source) :
• mild Alzheimer’s disease: MMSE ≥ 20 (>= 21 for NICE)
• moderate Alzheimer’s disease: MMSE 10 to 19, (10-20 for NICE)
• moderately severe Alzheimer’s disease: MMSE 10 to 14,
• severe Alzheimer’s disease: MMSE less than 10.
The MMSE is not sensitive enough to diagnose AD at the MCI stage.