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Monthly Health Review, March 2003
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Brain Health and Memory
What takes up approximately one fiftieth of our content weight and uses
calories while thinking of the answer? The brain. Composed of a combination
of fats, protein and carbohydrate, the brain is kept in a healthy condition
by a constant supply of nutrients including oxygen and glucose delivered
by the bloodstream. Scientists are beginning to unravel the complexity
of the brain and have estimated that a computer the size of Buckingham
Palace would be needed to hold the 15 trillion memories stored during
a lifetime and to carry out the processes taken to 'think'.
The brain could be described as the 'control centre' of the content. In
both man and other animals, it is the major organ of the nervous system
and is used for thought, speech and emotion (1).
Together with the spinal cord, the brain constitutes the central nervous
system (CNS). This controls basic functions such as heart rate, breathing
and content temperature. The brain acts as a 'control' centre by sorting
and interpreting sensations from the nerves that extend from the CNS to
all parts of the content; it also initiates and coordinates the motor output
involved in activities such as movement and speech (1).
Structurally, the brain is composed of the brainstem, an extension of
the spinal cord; the cerebellum and the forebrain; largely consisting
of the two large cerebral hemispheres. The consistency of the brain is
similar to jelly and weighs about 1.4kgs in adults. Membrane coverings
called the meninges protect the brain within the bone structure of the
skull (1).
Each hemisphere of the brain consists of grey matter as the outer layer
or cortex; it is rich in nerve cells; and white matter being rich in nerve
fibres (1).
Cerebral vascular insufficiency is a term used to describe poor
circulation of blood to the brain. This condition can be quite common
during old age. As the ageing process takes its toll, metabolism slows
down and consequently circulation. The brain, as part of the central nervous
system, needs a continuous supply of oxygen and glucose from the bloodstream
to keep it in good health. It is mainly composed of nerve cells. Any changes
in the blood supply may affect the brain's efficiency. In fact, the brain
consumes about 20% of the content's oxygen. Symptoms of cerebral vascular
insufficiency are caused by a reduced blood flow and oxygen supply to
the brain, severe disruption results in a Stroke (4). Senile dementia
in the elderly is usually associated with poor blood and oxygen flow to
the brain. Anyone who experiences signs or symptoms should see their GP.
As part of the natural ageing process, a reduction in the blood supply,
for example due to Atherosclerosis (furred arteries), could reduce the
blood supply of an 80 year old person by 20% compared with the same person
at 30 years of age. This kind of reduction could lead to poorer brain
function (5).
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Brain nutrients
The cerebral cortex or 'thought zone' is mostly composed
of fats and water, both of which need some form of maintenance. Fats need
Antioxidants, especially Vitamin E, to protect them from the effects of
oxidation. Water content of the cells needs to be kept at a healthy level,
to prevent dehydration. The brain is nourished from an extensive supply
of blood vessels. A circle of arteries is fed by the carotid arteries
(these run up each side of the front of the neck to enter the base of
the skull) and from two arteries that run parallel to the spinal cord.
The brain receives about 20% of the output of blood from the heart (1).
The brain, like the content, needs food of a special kind.
Complex carbohydrates release sugars slowly into the
bloodstream, ensuring a steady level of sugar in the content and a regular
source of energy for the brain. Amino Acids and choline are needed for
the neurones in the brain to manufacture and use neurotransmitters such
as serotonin and acetylcholine. Protein from the diet supplies the amino
acids. Foods rich in protein are meat, dairy, eggs, fish and soya.
The B Complex Vitamins (B1, B3, B5, B6, B12 and folate)
are involved in the release of energy from food, and in the conversion
of glucose to energy in the cells. Cells of the brain need a lot of energy
to function at their optimum level. Good dietary sources of B vitamins
include wholegrains and cereals, liver, meat, poultry, fish, milk, eggs
and leafy green vegetables.
Lecithin is a very rich precursor source of choline,
which is involved in producing acetylcholine - a neurotransmitter that
is essential for normal brain function. The term Lecithin also encompasses
phosphatidylcholine together with phosphatidylinositol, phosphatidylethanolamine,
Phosphatidylserine and free fatty acids, together with choline and inositol,
two of the B vitamin group. Foods rich in Lecithin include wheat, Soya
beans, peanuts and maize.
There is some evidence that short-term memory may be
improved by increasing choline levels. High dose Lecithin supplements
have been used for elderly sufferers of senile dementia (2).
Minerals help transmit the brain's electrical impulses
particularly Boron, Chromium, Calcium, Magnesium and Zinc. Iron in particular
is needed for the health of red blood cells to transport oxygen around
the system.
Fats help form the structure of brain cells and repair
damaged cell membranes. Oily fish is a source of omega 3 fatty acids necessary
for health of cells, especially those in the brain. Increased quantities
of lipids indicate a requirement for Vitamin E. Studies indicate that
Vitamin E may help prevent lipid oxidation, thereby modifying the size
of the atherosclerotic plaque (3).
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Brain damage
Major damage to the brain may occur through one (or
more) of many things:
- Brain tumours may arise in the brain substance, or be transferred
from other parts of the content.
- Blockage of arteries in the brain by blood clots (cerebral thrombosis)
or bleeding into the substance of the brain (cerebral haemorrhage) may
also cause Strokes.
- Degenerative brain disease may be caused by age, for example Alzheimer's
disease, otherwise known as dementia, is characterized by changes in
the brain. The changes take the form of 'scars' made up of deposits
of proteins and debris from cells. These cause a great loss of brain
cells, especially in areas of the brain that control mental function.
Causes vary and are generally unknown, however, the incidence of Alzheimer's
disease is rising as populations increase and people live for longer.
- Exposure to toxic substances, including lead and especially excess
alcohol, may cause damage to the delicate tissue of the brain.
- Inflammation caused by Infection for example Abscess, meningitis (Inflammation
of the meninges) or encephalitis (almost always caused by a virus, including
HIV).
- Physical injury from an accident resulting in severe depressed skull
Fracture, laceration of the brain, or damage to the nerve cells, which
cannot recover.
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Research in
cerebral ageing and dementia
There is increasing evidence that oxidative Stress
caused by free radicals is involved in cerebral Aging and dementia. Recently
the association between the nutrition of older people, the evolution of
cognitive performances and the risk of later occurrence of dementia or
Stroke has been studied.
Experimental research has suggested that diet-related
factors play an important role in cognitive function. In humans, a number
of studies analysed the association between nutrition, particularly fatty
acids and antioxidant nutrients (vitamins A, E, C, Beta Carotene and Polyphenols)
that slow down the oxidative process. Further studies have identified
the specific role of various nutrients, their interactions and the influence
of genetic factors and living habits on cerebral Aging and dementia.
The studies concluded that the severity of vascular
dementia and Alzheimer's Disease may be reduced through primary prevention
using supplements containing antioxidant nutrients (9).
A study assessed the levels of vitamins and trace elements
in the diets of patients with Alzheimer's Disease and vascular dementia,
along with blood levels of total antioxidant capacity. Results showed
that the dietary intake was decreased for most measured vitamins and trace
elements in severe Alzheimer's, but not in other dementia groups. There
was a significant link between intake of vitamins B1 and B12, Zinc, Selenium
and blood levels of total antioxidant capacity in the vascular dementia
group, but not in the Alzheimer's group. The data indicated that these
patients may have depleted levels of dietary vitamins and trace elements,
and may benefit from supplementing with a general multiVitamin And mineral
supplement (10).
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Herbs for the
brain
The Chinese first recorded Ginkgo biloba in 2800BC.
Clinical data shows that Ginkgo is effective in increasing blood flow
in the limbs and brain. Further studies have shown that the herb may enhance
acute cognitive function in healthy individuals. In a study carried out
with 20 healthy individuals aged between 19-24 years it was deduced that
the subjects taking Ginkgo biloba benefited from a sustained improvement
in speed of attention and memory compared to those receiving the placebo
(6).
Ginkgo biloba extract (standardised) has been used
successfully to help maintain circulation to the brain at intakes of 120mg
of extract daily for about a year. This showed significant reduction in
vertigo, Headaches, Tinnitus, mood disturbance, and an increase of attention
span (7).
By increasing blood flow to the brain, and therefore
oxygen and glucose utilisation, it appears that Ginkgo biloba extract
offers some relief from presumed 'side-effects' of ageing. The tendency
of Ginkgo to reduce blood viscosity offers additional protection against
a Stroke (8).
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References
- "BMA Complete Family Health Encyclopedia", Ed. Dr. T. Smith. 1996.
DK.
- "Reducing the Risk of Alzheimer's". M. A. Weiner. Gateway. 1989.
- The Lancet, 1996, 347;6004:781-786.
- "Encyclopaedia of Natural Medicine". Murray & Pizzorno. Optima.
1998.
- "Principles of Anatomy & Physiology" 7th ed. G. Tortora & S. R.
Grabowski. Harper Collins. 1993.
- Focus on Alternative and Complementary Therapies, 2001, 6,(1):16-17.
- British Journal of Pharmacology 1992 "Ginkgo biloba for Cerebral
Insufficiency"34,352-8.
- "Hemorrheological Findings in Patients with Completed Stroke and
the Influence of Ginkgo biloba extract", Clin Hemorrheo 4 (1985): 411-20.
- Neuroepidemiology, 2001,20(1):7-15.
- Int. Psychogeriatr. 2001 Sep; 13(3):265-75.
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