Chemistry Reference
In-Depth Information
Chapter 21
Metals and Neurodegeneration
Introduction
395
Metal-based Neurodegeneration
395
Neurodegenerative Diseases Associated with Metals
401
INTRODUCTION
As actuaries confront life insurance companies in the developed world with their tables of life expectancy over
the next decades, some very important positive and negative points emerge from their projections. One of the
most striking is that our children's children will live to be centenarians. Bravo, what enormous progress we
have made in extending the longevity of the human race! But this progress has been won at what cost? Given
the present correlation between the incidence of debilitating neurodegenerative diseases and dementias, like
Alzheimer's and Parkinson's disease, with increasing age, it is alarming to contemplate a situation, where we
have only extended our life expectancy, in order to confront the probability that we will be struck down by
diseases which will virtually reduce our existence to little more than an advanced vegetative state. In stark
terms, what this means is that we must be just as concerned about the quality of life of our ageing population as
about their life expectancy. The recent statistics published by the WHO of estimates of the incidence of
Alzheimer's disease, by far the most frequent form of dementia in Western society do not make for encour-
aging reading. It is estimated that there are currently about 18 million people worldwide with Alzheimer's
disease. This figure is projected to nearly double by 2025 to 34 million. Much of this increase will be in the
developing countries, and will be due to the ageing population. While Alzheimer's disease can occur at any
age, its occurrence is much more common as the years go by. In fact, the rate of occurrence of the disease
increases exponentially with age, which means that it occurs very rarely among those 40
50 years old,
increases between 60 and 65 years, and is very common over 80 years. Combining the results of several
studies, the rates of occurrence of Alzheimer's disease estimated in the general population in Western societies
are shown in
Figure 21.1
.
e
METAL-BASED NEURODEGENERATION
Over the last decade, it has become more and more widely accepted that inflammation, associated with
dysfunction of metal ion homeostasis (Fe, Cu, and Zn) accompanied by concomitant oxidative stress, is a key
factor in a large number of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease,
Huntington's disease, Amyotrophic lateral sclerosis (ALS), multiple sclerosis, Friedreich's ataxia, and
others (
Crichton & Ward 2006
). Support comes from the observation that AD, PD, and many other neuro-
degenerative diseases are characterised by increased levels of some of these metal ions in specific regions of
the brain.
