杏吧原创

EVERYONE wants to be cleverer, think faster, remember more. Thus the
endless appeal of advertisements that promise to boost your brainpower and
provide total recall.

By the next century鈥攚hich isn鈥檛 far off鈥攖hey might also sit
alongside ads for drugs that have been 鈥渟cientifically proven鈥�. Progress towards
drugs that boost memory is finally being made (see p 32).

Currently, the most remarkable results are coming from researchers in
California. They have developed 鈥渁mpakines鈥�, drugs which amplify the signal
carried by glutamate, a neurotransmitter involved in the brain鈥檚 memory
circuits. It appears to help rats remember the way around a maze and it may also
boost short-term recall in humans.

Two things have hastened progress. First, an epidemic of Alzheimer鈥檚 disease
is spreading across the ageing, advanced nations. Four million people in the US
and 600 000 in the UK are thought to suffer from the disease. Looking after huge
numbers of sufferers is going to place a gigantic burden on health budgets.

Not surprisingly, many of the world鈥檚 big drug companies are pumping huge
sums of money into research to develop drugs that might help people with
Alzheimer鈥檚. Because of the way the drugs work, they may also boost the mental
powers of healthy people.

Secondly, we now know a lot more about the way chemicals carry electrical
signals between nerve cells in the brain. The powerful tools of molecular
biology are giving us the ability to interfere with their production and
reception. Designing drugs which boost a neurotransmitter鈥檚 signal is becoming
almost routine.

These developments have left us in a strange position. We have discovered
much about how the various classes of nerve cells work and we have amazing
powers to interfere with their function. But we have very little idea how the
thousands of billion nerve cells in a single human brain work together to give
us all the sensations and feelings of being human.

It as though we were investigating an early digital computer and had learnt
how to manipulate the signals going through its diodes. But we didn鈥檛 know how
the computer worked as a whole or what the diodes really did. So messing with
the computer鈥檚 diodes might seem a recipe for making the machine go haywire.

Might trifling with neurotransmitters end up the same way? We can be sure
that any drug designed to boost the brain function of young, healthy people is
not going to work well for long. If the brain could be enhanced by making simple
modifications to its neurotransmitters, evolution would have taken advantage of
the opportunity long ago. By giving some neurotransmitters a lift, we can expect
the effect experienced by athletes on stimulants鈥攂oost followed by
crash.

Much more worrying, of course, would be a drug that really did send the brain
AWOL. But surely such a drug would never reach the market because anyone who
tried it would protest its horrors? Yes and no . . .

In the case of people suffering from Alzheimer鈥檚, real ethical issues are
raised*. If we discovered a drug that restored some short-term memory to
Alzheimer鈥檚 patients, they might appear to be better off, perhaps even in
something as trivial as being able to remember the way back to their own
beds.

But we might never find out if the drug affected them in other ways, perhaps
increasing their mental suffering, because Alzheimer鈥檚 patients cannot always
give a coherent account of how they feel. As one recent review of the field
drily put it 鈥渋ssues regarding the assessment of patients have not been
completely resolved鈥�.

It would be a tragedy if new drugs for Alzheimer鈥檚 turned out to make
patients more manageable but also trapped them deeper in their private hell.
Indeed, research on Alzheimer鈥檚 is now turning away from drugs that try to
overcome cognitive symptoms. Instead, the focus is shifting to growth factors
and drugs that boost neural metabolism in the hope that the disease can be
stopped before it is too far advanced.

That鈥檚 good news for those at risk from Alzheimer鈥檚 although it might not
spin off many drugs for those of us who read ads for 鈥渋ncreased memory power鈥�
with hope.

* A Ciba Foundation meeting to be held in London on 10 February will
discuss the ethics of cognitive enhancers.