Biomedical Engineering Reference
In-Depth Information
limbs. The identified regions associated with so-called 'higher' functions such as
cognition, affect, memory and decision-making will lead to the development of
direct brain-computer interfaces in the future. The first steps represented by
successful cochlear implants continued with the implanted electrodes for deep
brain stimulation for treating essential tremor, Parkinson's disease and
depression. New technologies will improve the interface between the electrodes
and the brain tissue and the performance of the electrodes. Implanted electrode
arrays in the visual cortex will be further miniaturized and refined, making
possible to enable at least the detection of light and dark, form and movement,
and greatly improve the quality of life for blind people.
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7.10 Dementia, Alzheimer's Disease and Reversing the
Ageing Process in the Brain
Progress in medicine and higher standards of living have greatly increased the
life expectancy of the general population, at least in the developed countries,
without addressing the alarming issues concerning cognitive decline and the
characteristic frailty of old age. The old theory that the brain inexorably loses
neurons without being able to replace them does not appear to hold water
anymore. Regeneration does occur in the flexible structure of the brain,
especially in the hippocampus, in the areas associated with memory and
learning. However, the process is slow and is overcome by the loss of plasticity
and massive loss of grey matter in some older people. It is not clear why this is
not a general phenomenon and how sometimes lucidity and sharpness of mind
is still retained, even in the presence of degenerative processes.
There are millions of people worldwide affected by dementia. Alzheimer's
disease is accepted as the main cause, with people over 85 in the major risk
category. Only a very small percentage of the cases are familial, having genetic
causes; the rest are random and probably highly influenced by previous lifestyle
choices concerning exercise, nutrition and social activities, and keeping an
enthusiastic interest in learning new things. Environmental risks, gender and
the number of previous head injuries seem to have an influence too. Cellular
research can use advanced in vitro techniques to study the accumulation of the
amyloid plaque, the biochemical contribution of amyloid precursor proteins or
genetic relevance for the neuron death which leads to the disintegration of the
cognitive structures of the brain. Some preliminary attempts were actually
presented in this topic. A pharmacological approach involving neurotrophic
factors and specific drugs seems a better choice than stem cell therapy, because
neuron death is widespread throughout the brain and not localized to limited
regions as in Parkinson's. Existing drugs have only a palliative effect and major
efforts are targeting the degenerative processes, based on new advances in the
understanding of complex neurological and immunological mechanisms. More
effective drugs are expected to appear in the next decade, not only to diminish
the symptoms, but to stop or reverse the decline, offering the joy of an
independent, normal and fulfilled life to senior citizens.
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