Academic journal article South African Journal of Psychiatry

Dementia

Academic journal article South African Journal of Psychiatry

Dementia

Article excerpt

1. Introduction

By definition, dementia is an acquired global impairment in memory, personality and intellect in an alert patient, that is sufficiently severe to interfere with social and/or occupational functioning. In the absence of a stroke or rapidly growing cerebral tumours (among other causes), the onset is usually gradual and the cognitive decline is always progressive. In the absence of a cure for the disease, nonpharmacological inventions and the judicious use of pharmacotherapy may not only help the patient and alleviate the stress on the caregiver, but can also help in delaying institutionalisation.

1.1 Prevalence and burden of disease

The worldwide prevalence of dementia currently approximates 35.6 million people, a figure set to rise to 65.7 million by 2030 and (by doubling every 20 years) to 115.4 million by 2050. Nearly two-thirds of individuals with dementia live in developing countries, where the sharpest increase in numbers is said to occur. [1] The prevalence of dementia is approximately 5-7% of the elderly population. Starting at 1% for 60-year-olds, the prevalence doubles every 5.1 years, rising to some 30-45% of those aged 85 and older [2,3] in developed countries, while doubling every 7 years in developing countries. [4] Among the South African elderly an estimate would place the number of dementia sufferers at 250 000, with some 35 000 of these suffering from Alzheimer's disease (AD).

Twenty per cent of AD patients are alive after a 15-year period, the mean duration of illness being some 10-12 years. [5] Of the people with late-onset (65 years and older) dementia in developed countries, more than half have AD, some 15% have vascular dementia (VaD), and the remaining 30%, a variety of some 60 other forms of dementia. [6] Many cases of AD exhibit a confluence with cerebrovascular disease (CvD). [7] The total worldwide societal cost of dementia was estimated at US$422 billion in 2009, which included US$142 billion (34%) for informal care. [8] Americans estimate that dementia costs them some US$100 billion per year, [1] and yet a delay in the onset of AD by only 5 years would halve the prevalence of the disease, resulting in enormous savings of human misery and cost to society. [5,9] In all cases there are profound psychosocial effects on the caregiver, in whom the rates of depression, substance abuse, hospitalisation and physical illness are all increased. [9]

1.2 Causes and types of dementia

In the South African population, dementia due to the HIV/AIDS complex (affecting mainly the younger age group) is the most common. Among the elderly the most prevalent is VaD, followed by AD, which is on the increase. [7]

1.2.1 Alzheimer's disease

The neuropathological hallmarks of AD are amyloid plaques, neurofibrillary tangles, and synaptic and neuronal loss with subsequent brain atrophy. Macroscopically, and with neuro-imaging (magnetic resonance imaging (MRI) and computed tomography (CT) scan), this demonstrates as flattening of gyri, widening of sulci, atrophied medial temporal lobes and enlarged ventricles. Pathology at microvascular level has increasingly been implicated in the aetiology of AD, blurring the boundaries with VaD in many cases. AD and possibly most other dementias tend to follow a sinusoidal course in that the initial slow, progressive deterioration accelerates rapidly before flattening out towards the end-in keeping with the 3 stages of mild, moderate and severe. [10]

The duration of illness may be as short as 6 months or as long as 20 years, with an average of 12 years. Neurochemically there are deficits in neurotransmitters including acetylcholine, noradrenaline, serotonin, and somatostatin. Specific mutations on chromosomes 21, 14 and 1, inherited as familial autosomal dominant traits with full penetrance, are found in some 1% of all AD patients. Here the illness usually presents itself in the 40s or early 50s and is essentially 'pre-senile' in onset (i. …

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