‘Get Smart’ Drug
According to
Danielle
Turner, author of this research, ‘The drug appears to make people stop
and
think – after receiving it the volunteers were significantly better at
inhibiting impulsive responding and at reflecting on the problems we
set them.’
This drug could
be
invaluable to people who are overly impulsive or have specific kinds of
cognitive deficits. People who suffer
from attention deficit disorder (ADHD), or who have impairments in
certain
types of memory, problem-solving, or planning, all fall into this
category. Other compounds have been used
to treat these
conditions in the past, but all of them have involved unfortunate
side-effects
such as addiction and increased anxiety.
Modafinil is not addictive and does not appear to have many side
effects.
‘[Drugs such as]
amphetamine and methylphenidate [Ritalin] have been used previously to
help
improve some aspects of people’s performance, but they often have the
disadvantage of causing impairments in other functions, and are also
associated
with serious side effects such as addiction.
Modafinil, in contrast, has been shown to have few side effects
and
there is no evidence that it is
addictive’ says Turner.
So how does
modafinil work
and why doesn’t it have the same side effects as other cognitive
enhancers? According to Turner, that is
a difficult question. ‘The exact
mechanism of action of modafinil is unknown.
[Other cognitive enhancers] cause significant changes in the
transmission of dopamine and noradrenaline [chemical messengers known
to be
involved in keeping the brain alert, and also in sensations of
pleasure, as
well as in addiction]. These changes are
likely to account in part for the cognitive enhancing properties
associated
with these drugs, but also for the associated negative side-effects.’ That modafinil uses a different mechanism is
quite clear, however what this mechanism actually is
remains to be determined.
When pushed to
guess at the
mechanism, Turner conjectures ‘[Modafinil] might act indirectly via
other
chemical messengers within the brain, possibly the noradrenergic system. This would explain the enhanced cognitive
effects and also the changes in physiological measures [such as
increased heart
rate, blood pressure] that we see.’
In her recent
research,
conducted together with Prof. Barbara Sahakian, also from Cambridge
University,
Turner tested 60 healthy male volunteers, each of whom swallowed either
a dummy
tablet or a dose of modafinil (200 or 400 milligrams).
To make certain that any results observed
were really due to actions of the drug, rather than placebo effects or
‘faking’, neither volunteers nor experimenters were allowed to know
which
tablet had been taken until all the results were tabulated.
Having swallowed
their pills,
volunteers performed a variety of different tasks using computer games
and
touch-sensitive monitors. In one, which
tested for impulsiveness, they had to respond as fast as possible to
arrows
requesting that right- or left-hand buttons be pressed. Occasionally,
they were
quite suddenly asked NOT to press either button. People
who had only swallowed a dummy
pillneeded more warning time to stop than those who had taken a small
dose of
modafinil, and those who had taken a big dose of modafinil needed the
least
warning time of all.
People who took
modafinil
also performed better at spatial planning tasks and did better on two
different
tests for of memory than people who didn’t.
They were able to remember and repeat (in the order they were
presented,
both forwards and backwards) more numbers than people who had taken the
dummy
pills only, and showed an enhanced memory for visual patterns.
All of the
information
available to date suggests that modafinil will provide a lifeline for
people
who have poor memories or are uncontrollably impulsive.
But will this new medication really
work?
Turner aims to find out as soon as possible.
The next challenge on her research agenda is
to determine whether modafinil works for patients as well as for
healthy
volunteers. She will soon try the drug
on teenagers and adults suffering from ADHD in order to find out
whether it
helps them in the ways she expects. She
will also use brain imaging techniques to determine which areas of the
brain
are involved in the tasks her patients perform, and which are
influenced by
modafinil. This information will be
extremely useful in determining how the drug works.
For more information contact:
Danielle Turner
Phone: 01223
336010
Email: dct23@cam.ac.uk