someone in need
08-18-2005, 03:56 AM
Do non diseases cause seizures, delerium tremors, hallucinations
(withdrawl)
What Twins Can Tell Us
Much of the new evidence comes from comparisons of identical and
fraternal twins. Since identical twins develop from a single
fertilized egg that divides after conception, both have the exact same
genetic makeup and can be expected to be alike in most respects. For
example, identical twins are always the same sex, always have the same
hair and eye color, and usually reach the same adult height and
weight. Studies of identical twins separated at birth and raised in
different families have produced compelling evidence of the power of
their genetic bond. In addition to their strikingly similar physical
development, the twins have remarkably similar tastes, preferences,
and interests.
Fraternal twins develop from two different eggs fertilized by two
different sperm. Fraternal twins are no more closely related than
siblings born separately.
If environment were the sole cause of alcoholism, the rate of
alcoholism among twins raised in drinking families should be the same
regardless of whether they are identical or fraternal. But if a
genetic predisposition were responsible, the rate of alcoholism would
be similar for both identical twins, who have exactly the same genes.
Studies have shown that when one identical twin is alcoholic, the
other is four times more likely to be alcoholic than when one
fraternal twin is alcoholic, indicating that genetics play a part in
alcoholism.
There have been many other studies aimed at showing whether nature or
nurture is to blame for alcoholism. One of the first (Donald Goodwin,
1978) compared 133 sons of alcoholics adopted and raised by
nonalcoholic parents to a similar group of adoptees with no genetic
history of alcoholism. The sons of alcoholics were three times more
likely to become alcoholic than the sons of nonalcoholic parents. A
larger study in Sweden (C.R. Cloringer, M. Bohman, and S. Sigvardsson,
1981) followed 3,000 adoptees separated from their biological parents
at an early age and raised by non-relatives. The risk of these
children becoming alcoholic was two and a half times higher when one
biological parent was alcoholic.
Researchers have also studied what happens to the children of
nonalcoholics who are adopted into households where one parent is
alcoholic. They have found no evidence that being raised by an
alcoholic parent predisposes a child to alcoholism.
Under the Microscope
Research indicates that some hereditary abnormality of body or brain
chemistry must be passed from generation to generation to account for
the fact that alcoholism runs in families. The search for such an
abnormality has yielded a number of valuable clues. The first was the
discovery of certain unusual brain-wave patterns among alcoholics and
their non-drinking children. P-300 brain waves, which influence
memory, were absent or weaker than normal among the alcoholic families
studied. (Not coincidentally, memory lapses are common complaints
among alcoholics.)
Researchers discovered that alcoholics are much more likely than
nonalcoholics to have a certain gene affecting receptor sites for
dopamine, a central-nervous-system neurotransmitter that facilitates
communication between nerve cells and is associated with pleasure
seeking behavior. Researchers theorize that the newly discovered gene
alters dopamine receptor sites in the brain. Receptor sites can be
thought of as locks that can be opened only by the correct chemical
key-in this case, dopamine. Exactly how the new gene predisposes a
person to alcoholism isn't yet known, but the fact that it was found
in 77 percent of the alcoholics studied and was absent in 72 percent
of nonalcoholics suggests that it underlies some types of alcoholism.
More Chemical Clues
Discoveries about the way alcohol is processed in the body have
provided further evidence of a genetic link. For example, Harvard
scientist (L. Tunglai et al 1977) recently came upon a previously
unknown liver enzyme responsible for metabolizing alcohol. This
enzyme, alcohol dehydrogenase II (II ADH), can process or oxidize
alcohol up to 40 percent more efficiently than the liver enzymes most
of us have. People who have this enzyme and most of us do not- have an
inborn ability to drink very large amounts of alcohol without becoming
intoxicated. These are the folks who can drink many of us under the
table without getting the least bit tipsy and/or feeling hung over the
next morning.
Researchers have also discovered that the absence of a crucial liver
enzyme accounts for the fact that very few Orientals become
alcoholics. In fact, many Asians get sick whenever they drink. Their
pulses race and they feel dizzy and nauseated. The explanation for
this peculiar reaction is the fact that many Orientals have only one
liver enzyme that processes alcohol, rather than the two found in
people from other parts of the world. About half the Oriental
population is missing this second crucial enzyme.
Alcoholics and nonalcoholics process alcohol differently. When alcohol
reaches the liver, it is changed into acetaldehyde, a harmful
byproduct of alcohol metabolism that can damage liver cells. Normally
the liver rapidly transforms the harmful acetaldehyde into a neutral
substance called acetic acid or acetate. The acetic acid is then
converted into carbon dioxide and water. We expel the carbon dioxide
through respiration and the water through urination.
Until recently, it was believed that the liver always handles alcohol
in the same way. But new research shows that a different scenario
occurs among certain alcoholics and children of alcoholics with no
drinking experience (Figure 2). Their livers change alcohol into
acetaldehyde at twice the normal rate, while the subsequent conversion
of acetaldehyde into acetic acid is abnormally slow and takes twice as
long as usual. The accumulation of acetaldehyde damages liver cells,
which become abnormally large as they strive to get rid of the
accumulated acetaldehyde. This damage affects the liver's ability to
absorb and utilize the nutrients needed for good health. To make
matters worse, excess acetaldehyde escapes the liver and travels
through the bloodstream to the heart, where it can be very damaging
(it interferes with the protein synthesis of the heart muscle). It
also reaches the brain, where it blocks proper neurotransmitter action
in creating normal feelings, behavior, and memory. The unused natural
neurotransmitters begin to build up and combine with the acetaldehyde
to form potent psychoactive compounds called tetrahydroisoquinolines
(THIQs), which are remarkably similar to opiates. THIQs fit in the
same receptor sites in the brain as natural pain-killing chemicals
called endorphins and such narcotics as morphine and heroin.
(withdrawl)
What Twins Can Tell Us
Much of the new evidence comes from comparisons of identical and
fraternal twins. Since identical twins develop from a single
fertilized egg that divides after conception, both have the exact same
genetic makeup and can be expected to be alike in most respects. For
example, identical twins are always the same sex, always have the same
hair and eye color, and usually reach the same adult height and
weight. Studies of identical twins separated at birth and raised in
different families have produced compelling evidence of the power of
their genetic bond. In addition to their strikingly similar physical
development, the twins have remarkably similar tastes, preferences,
and interests.
Fraternal twins develop from two different eggs fertilized by two
different sperm. Fraternal twins are no more closely related than
siblings born separately.
If environment were the sole cause of alcoholism, the rate of
alcoholism among twins raised in drinking families should be the same
regardless of whether they are identical or fraternal. But if a
genetic predisposition were responsible, the rate of alcoholism would
be similar for both identical twins, who have exactly the same genes.
Studies have shown that when one identical twin is alcoholic, the
other is four times more likely to be alcoholic than when one
fraternal twin is alcoholic, indicating that genetics play a part in
alcoholism.
There have been many other studies aimed at showing whether nature or
nurture is to blame for alcoholism. One of the first (Donald Goodwin,
1978) compared 133 sons of alcoholics adopted and raised by
nonalcoholic parents to a similar group of adoptees with no genetic
history of alcoholism. The sons of alcoholics were three times more
likely to become alcoholic than the sons of nonalcoholic parents. A
larger study in Sweden (C.R. Cloringer, M. Bohman, and S. Sigvardsson,
1981) followed 3,000 adoptees separated from their biological parents
at an early age and raised by non-relatives. The risk of these
children becoming alcoholic was two and a half times higher when one
biological parent was alcoholic.
Researchers have also studied what happens to the children of
nonalcoholics who are adopted into households where one parent is
alcoholic. They have found no evidence that being raised by an
alcoholic parent predisposes a child to alcoholism.
Under the Microscope
Research indicates that some hereditary abnormality of body or brain
chemistry must be passed from generation to generation to account for
the fact that alcoholism runs in families. The search for such an
abnormality has yielded a number of valuable clues. The first was the
discovery of certain unusual brain-wave patterns among alcoholics and
their non-drinking children. P-300 brain waves, which influence
memory, were absent or weaker than normal among the alcoholic families
studied. (Not coincidentally, memory lapses are common complaints
among alcoholics.)
Researchers discovered that alcoholics are much more likely than
nonalcoholics to have a certain gene affecting receptor sites for
dopamine, a central-nervous-system neurotransmitter that facilitates
communication between nerve cells and is associated with pleasure
seeking behavior. Researchers theorize that the newly discovered gene
alters dopamine receptor sites in the brain. Receptor sites can be
thought of as locks that can be opened only by the correct chemical
key-in this case, dopamine. Exactly how the new gene predisposes a
person to alcoholism isn't yet known, but the fact that it was found
in 77 percent of the alcoholics studied and was absent in 72 percent
of nonalcoholics suggests that it underlies some types of alcoholism.
More Chemical Clues
Discoveries about the way alcohol is processed in the body have
provided further evidence of a genetic link. For example, Harvard
scientist (L. Tunglai et al 1977) recently came upon a previously
unknown liver enzyme responsible for metabolizing alcohol. This
enzyme, alcohol dehydrogenase II (II ADH), can process or oxidize
alcohol up to 40 percent more efficiently than the liver enzymes most
of us have. People who have this enzyme and most of us do not- have an
inborn ability to drink very large amounts of alcohol without becoming
intoxicated. These are the folks who can drink many of us under the
table without getting the least bit tipsy and/or feeling hung over the
next morning.
Researchers have also discovered that the absence of a crucial liver
enzyme accounts for the fact that very few Orientals become
alcoholics. In fact, many Asians get sick whenever they drink. Their
pulses race and they feel dizzy and nauseated. The explanation for
this peculiar reaction is the fact that many Orientals have only one
liver enzyme that processes alcohol, rather than the two found in
people from other parts of the world. About half the Oriental
population is missing this second crucial enzyme.
Alcoholics and nonalcoholics process alcohol differently. When alcohol
reaches the liver, it is changed into acetaldehyde, a harmful
byproduct of alcohol metabolism that can damage liver cells. Normally
the liver rapidly transforms the harmful acetaldehyde into a neutral
substance called acetic acid or acetate. The acetic acid is then
converted into carbon dioxide and water. We expel the carbon dioxide
through respiration and the water through urination.
Until recently, it was believed that the liver always handles alcohol
in the same way. But new research shows that a different scenario
occurs among certain alcoholics and children of alcoholics with no
drinking experience (Figure 2). Their livers change alcohol into
acetaldehyde at twice the normal rate, while the subsequent conversion
of acetaldehyde into acetic acid is abnormally slow and takes twice as
long as usual. The accumulation of acetaldehyde damages liver cells,
which become abnormally large as they strive to get rid of the
accumulated acetaldehyde. This damage affects the liver's ability to
absorb and utilize the nutrients needed for good health. To make
matters worse, excess acetaldehyde escapes the liver and travels
through the bloodstream to the heart, where it can be very damaging
(it interferes with the protein synthesis of the heart muscle). It
also reaches the brain, where it blocks proper neurotransmitter action
in creating normal feelings, behavior, and memory. The unused natural
neurotransmitters begin to build up and combine with the acetaldehyde
to form potent psychoactive compounds called tetrahydroisoquinolines
(THIQs), which are remarkably similar to opiates. THIQs fit in the
same receptor sites in the brain as natural pain-killing chemicals
called endorphins and such narcotics as morphine and heroin.