Galantamine Is Good for Mice and Men
Damaged Brain Cells
Study using transgenic mice reveals galantamine’s unique mode of action
By Will Block
ehold the lowly mouse. Let us forget, for the moment, that
most people regard mice as vermin, to be dispatched as ruthlessly as possible,
with nary a thought to the fact that they really are kind of cute and cuddly, as
rodents go. And they have dynamite personalities too—at least Mickey did. And
cats love them . . . .
really loves mice? Medical researchers, that’s who.
To scientists trying to unravel the fantastically complex workings of the human
body in both health and disease, there’s nothing better than a mouse—better yet,
hundreds of them. Sure, there are also rats and guinea pigs and fruit flies and
roundworms and monkeys and Japanese quail (see the article on page 28 of this
issue), and even dogs and cats (dogs and cats?!), along with many other noble
creatures, all of which have given their all for the sake of medical research,
so that we humans could have longer, healthier, happier lives.
But for compact, easy-to-manage, fast-reproducing,
metabolically well-suited organisms on which to test our ideas on how to improve
the human condition, nothing beats your basic lab mouse. Without them—and all
the other animals mentioned—we would still be in the Dark Ages of medicine,
enduring immense amounts of human suffering as we (including our children)
succumbed to myriad fatal diseases that are now but a distant memory.*
Galantamine Resists Memory Impairment
Speaking of memory (uh, we were, weren’t we?) brings to
mind the subject of dementia, and Alzheimer’s disease in particular. There are
dozens of different forms of dementia, but Alzheimer’s is the most prevalent,
followed by vascular dementia; all the rest are small potatoes by comparison.
The hallmark symptom of Alzheimer’s is a progressive, irreversible memory loss
that ultimately robs its victims of their very identity.
Just when this dreadful process begins is hard to say,
because relatively benign forms of memory loss (which go by different names to
reflect their different spectra of symptoms) are a nearly universal feature of
aging. We’re all familiar with that kind of “old-folks” forgetfulness, and we
take it in stride, because we’ve accepted the idea of its inevitability. And we
don’t worry too much about it, because it’s harmless. Usually.
Uh-oh. When is it not harmless? You know the answer: when
it’s a setup for Alzheimer’s or some other form of dementia. A prevalent form of
memory impairment in otherwise healthy people is called mild cognitive
impairment (MCI), which can be thought of as a transitional phase between normal
aging and early (mild) dementia. There is no question that MCI is a major risk
factor for dementia, so it’s worthwhile (to put it mildly) to try to prevent it
or at least slow down its progression. The earlier one starts, the better.
Galantamine counteracted the
cholinergic neurons in
the mouse brains.
Possibly the best approach to this objective is to use
galantamine, a chemical compound isolated from various flowers, which has proven
to be beneficial in the treatment of mild to moderate Alzheimer’s disease and
which shows great promise—not surprisingly—in treating MCI as well. (See
Galantamine May Help with Mild Cognitive Impairment in last month’s issue of
Beta-Amyloid Is Bad Brain Matter
It would be great if there were a reliable method of
determining when Alzheimer’s disease was imminent or had already begun. Although
there is no such method yet, researchers are devising ever more sophisticated
tests of memory and other aspects of cognitive function, such as learning
ability. They are also making progress in methods of physical diagnosis through
brain imaging, using techniques such as computed tomography (CT) and magnetic
resonance imaging (MRI). The idea, of course, is to detect brain abnormalities
that are characteristic of Alzheimer’s disease.
One of the hallmark physical abnormalities of the disease
is deposits of a waxy plaque called beta-amyloid in certain regions of the
brain, notably the hippocampus, which is associated with memory and learning.
Beta-amyloid consists primarily of protein; it comes from a precursor protein
called . . . amyloid precursor protein (APP). The process is one result of
neurodegeneration—the degeneration of nerve tissue. And what causes that? Many
factors, probably. In a moment we’ll see what one probable factor is, based on
some recently published research in neuroscience.
Transgenic Italian Mice Get Alzheimer’s
Which brings us back to mice (that introduction had to be
leading somewhere). One of the great things about mice is that one can mess with
their genes, so to speak, in order to give them certain characteristics that are
useful in medical research. This is done using the techniques of genetic
engineering. One such technique is to transfer a gene from one type of organism
into the DNA of another, thus introducing a desired characteristic into the host
organism (in this case, a mouse). A mouse with such a transplanted gene in its
DNA is called transgenic. For example, one can bring in a gene responsible for
the production of an antibody (a specialized type of protein) that will
neutralize the action of a given protein normally found in the mouse’s cells.
The researchers tested
galantamine to see if it would
reduce beta-amyloid deposits—
and it did, markedly.
A group of researchers in Italy has made interesting use of
a type of transgenic mouse called AD11, in which an antibody produced by the
“alien” gene neutralizes the mouse’s nerve growth factor (NGF), a protein that
stimulates the growth of certain types of nerve cells. Now comes that “probable
factor” in neurodegeneration that we promised you a moment ago. Without NGF, the
poor little mouse’s aging brain suffers a form of progressive neurodegeneration
that resembles Alzheimer’s disease in many ways, both behavioral and
neuroanatomical, including the loss of neurons in certain parts of the brain and
the formation of beta-amyloid. (This jibes with the suggestion by some
scientists that a decrease in NGF function in human brains may be a contributing
factor in the onset of Alzheimer’s.)
Galantamine to the Rescue
So the AD11 mice get what appears to be experimentally
induced Alzheimer’s disease, and that makes them very useful for study. The
Italian researchers wanted to determine the extent to which the deficit in NGF
function in these mice could be linked to the observed neurodegenerative
symptoms, and, more importantly, to see whether these symptoms could be
prevented or alleviated by treatment with NGF or . . . galantamine.
Whoa! Trying NGF as a treatment in NGF-impaired mice is
obvious, but why galantamine? To be sure, we know that galantamine is an
effective treatment (probably the best treatment) for Alzheimer’s, but what is
its connection with NGF? Well, it turns out that NGF fosters the proper
development of a certain class of neurons in the basal forebrain during growth
and adulthood. These neurons are called cholinergic, because what makes them
work, so to speak, is the neurotransmitter acetylcholine. And galantamine’s
action in the brain is to boost the levels and activity of acetylcholine, via
two different mechanisms that we’ll touch upon below.
Galantamine’s advantage over the
drugs became dramatically
evident when two of the drugs
were tried in the mice—and
they were ineffective.
Here’s a recap: in the basal forebrain, a deficit of nerve
growth factor retards the development and proper function of cholinergic
neurons, which depend on acetylcholine as their neurotransmitter. This process,
which entails not only a loss of neuronal function but also a loss of many
neurons themselves, is a form of neurodegeneration. The researchers wanted to
know whether galantamine, a known anti-Alzheimer’s agent, would counteract this
specific form of NGF-related neurodegeneration in this specific kind of NGF-impaired
mouse. So they tried it—and it did (so did NGF, by the way). Galantamine
significantly “rescued” (in medical jargon) the cholinergic deficit by
preventing the loss of cholinergic neurons.
Galantamine Reduces Beta-Amyloid
The researchers also wanted to know whether galantamine
would reduce the deposits of the beta-amyloid precursor APP, which we mentioned
earlier. So they tried it—and it did, markedly (in this case, however, NGF had
no effect, for unknown reasons). As the mice aged, their APP deposits gradually
turned into beta-amyloid, and the researchers wanted to know whether galantamine
would reduce those deposits as well. So they tried it when the mice were 6–6.5
months old—and it did, markedly (and so did NGF, this time). The beta-amyloid
deposits were in the hippocampus.
Galantamine Helps Schizophrenic Man
Old joke: a guy asks a schizophrenic friend, “How are you?”
The answer: “I’m OK—and so am I.” Schizophrenia (the word means “split mind”) is
a psychotic disorder usually characterized by withdrawal from reality, illogical
patterns of thinking, delusions, hallucinations, and other forms of behavioral,
emotional, or intellectual disturbances.
Somewhat unexpectedly, case studies are beginning to emerge
regarding the successful use of galantamine in treating schizophrenia. We wrote
about one in the September 2002 issue. Here’s another:
Two physicians in Washington, DC, have reported on the case
of a 42-year-old man with a more than 20-year history of severe paranoid
schizophrenia. He had grandiose delusions and almost constant auditory
hallucinations. He had difficulty in bringing himself to perform ordinary daily
tasks, such as bathing. His memory was so poor that he rarely knew what day it
was, and he didn’t want to wash dishes because he couldn’t remember where to put
them afterward. During one 6-year hospitalization, he rarely got out of bed
except to smoke an occasional cigarette.
This poor fellow had for years been on a witches’ brew of
antipsychotic medications, including clozapine, fluphenazine, olanzapine,
ziprasidone, clonazepam, and trihexyphenidyl. They obviously weren’t working
very well. He was convinced that they were, however, and insisted on staying
with them. But he also expressed the desire for a “memory drug” to help in that
department. When his doctor obliged by giving him galantamine on top of all the
other stuff, there was a sudden, dramatic improvement in his condition, as
verified by standardized behavioral tests. In addition, he started taking daily
showers, learned where the dishes went, and reported feeling “spunky.”
Alas, it didn’t last long, because after 55 days he
suddenly quit the galantamine, having become convinced that it was causing a
tremor in his hand (it wasn’t). His condition immediately deteriorated to its
former deplorable state.
In reporting this case, the physicians cited scientific
arguments suggesting that galantamine’s astonishing effectiveness was due to its
ability to act as a modulator of nicotinic receptors in the brain. If that is
indeed true, it adds to a growing body of evidence that this feature, which
makes galantamine unique among anti-Alzheimer’s agents, is its most important
- Rosse RB, Deutsch SI. Adjuvant galantamine administration improves
negative symptoms in a patient with treatment-refractory schizophrenia. Clin
The results of the Italian research add a few more small
pieces to the huge puzzle that is Alzheimer’s disease. Many factors can be
involved in the chains of events leading to the neurodegeneration that is so
characteristic of the disease. The causal links among the various risk factors
involved, and their individual roles in forging those chains of events, remain
largely elusive, and no comprehensive theory that can account for all the
clinical and neuropathological features of the disease has yet emerged.
Meanwhile, however, it’s good to have a few more bits of
confirming evidence for the efficacy of galantamine in combating Alzheimer’s.
(We’re assuming that the mouse results would be valid in humans as well; that’s
usually a good assumption, but there’s no guarantee.)
Galantamine Modulates Nicotinic Receptors
A significant aspect of the Italian study was the discovery
that galantamine’s mode of action was not the same as that of the drugs—called
acetylcholinesterase inhibitors—that are widely used to treat Alzheimer’s
disease in humans. Although galantamine is itself an effective
acetylcholinesterase inhibitor and owes much of its efficacy to that fact, it
has an additional mode of action that the drugs do not have: it is a modulator
of nicotinic receptors in the brain. We need not go into the details of all this
here—they have been covered at length in previous articles about galantamine in
Life Enhancement.* Suffice it to say that this second mechanism gives galantamine a substantial advantage over the drugs in the Alzheimer’s arena.
That advantage became dramatically evident when the
researchers tried two of the Alzheimer’s drugs, tacrine and physostigmine, in
the transgenic mice: they were ineffective. From this and other evidence, they
concluded that galantamine must have acted in its own unique way, by modulating
the nicotinic receptors in the mouse brains.
Act Early to Head Off Alzheimer’s
The Italian research underscored what had already become
clear from numerous other studies on galantamine’s role as an anti-Alzheimer’s
agent: its efficacy is greatest in the early stages of the disease, before the
effects of the neurodegeneration have taken such a hold on brain function that
they become irreversible.
The researchers concluded that
galantamine must have acted
in its own unique way, by
modulating nicotinic receptors.
The message here, of course, is that early, preventive
action against the possibility of Alzheimer’s is a wise strategy—it’s easier to
hold off a weak foe than a strong one. So remember not to forget to be wise. And
the next time you encounter a mouse, be kind.
- Capsoni S, Giannotta S, Cattaneo A. Nerve growth factor and galantamine
ameliorate early signs of neurodegeneration in anti-nerve growth factor mice.
Proc Natl Acad Sci 2002 Sep 17;99(19):12432-7.
Galantamine provides a heralded dual-mode action for boosting cholinergic function: it inhibits the enzyme acetylcholinesterase, thereby boosting brain levels of acetylcholine, and it modulates the brain's nicotinic receptors so as to maintain their function. The recommended daily serving ranges from a low of 4 to 8 mg of galantamine to begin with to a maximum of 24 mg, depending on the individual's response.
For an added measure of benefit, it is a good idea to take choline, the precursor molecule to acetylcholine, as well as pantothenic acid (vitamin B5), an important cofactor for choline. Thus it is possible to cover all bases in providing the means to enhance the levels and effectiveness of your acetylcholine.
Will Block is the publisher and editorial director of Life