Coffee?!
No Thanks.
Many
hong kong students stay up late
to finish assignments or to cram that extra bit of
studying before tests. As a result, we tend to crave
for coffee in the morning in order to negate the
effects of staying up late at night. While we all
know that coffee contains an addictive ingredient,
caf fei ne, much less i s known about how th i s
chemical stimulant affects developing teenage
brains. A group of scientists supported by the swiss
national science foundation decided to investigate
this question.
As human testing is often considered unethical,
scientists typically use what they call “model
systems” – other organisms that model our body’s
responses. In this study, Dr. Reto Huber and his team
worked on 28 male rats. In both rats and humans,
the number of neurological connections increases
in childhood, peaks at puberty, and decreases as
our brains prune out the unwanted connections
between nerve cells known as synapses, or the
areas where two neurons connect. Synaptic
pruning is a critical part of brain maturation as it
increases the brain’s efficiency by reducing the
amount of ‘cluttering synapses’ [1].
In order to measure brain maturation, scientists
assessed three indicators: exploratory behavior,
synapse density, and slow wave activity in the brain
during sleep. Exploratory behavior towards a new
object increases as a rat matures, which elucidates
the curiosity of the rats towards new things. Synapse
density decreases due to synaptic pruning in
normal neurological development. The decrease in
synapse density implies that the activated neuron
has fewer places where it can pass on its message.
Neural signaling, measured by the brain’s slow wave
activity during sleep, also decreases as a result.
For five days after the start of puberty, Huber’s
rats received a fixed dosage of caffeine in their
drinking water that is equivalent to about three or
four cups of coffee a day for humans. Control rats
received normal drinking water with no caffeine.
T h e
researchers
then assessed
whether brain
ma t u r a t i o n i s
af fected i n each
g r o u p o f r a t s . To
quantif y explorator y
behavior, rats were exposed
to a new ob j ect and t he t i me
they spent interacting with it was
measu red. For synapse dens it y,
Huber sacrificed some of his rats after
treatment and stained for a protein
present in synapses to visualize the
locations of synapses and how close
they were to one another. In addition, the
scientists also implanted electrodes into the
brains of these rats and measured their slow
wave activities during sleep.
The findings were significant: all three indicators
suggested that the caffeine-treated rats have
less matured brains than the control rats. As the
caffeine-treated rats aged, both their synapse
density and brains’ slow wave activity did not
decrease as much as that of the rats in the control
group. The caffeine-treated rats also showed
weaker explorative behavior.
You may wonder, “what does an experiment
on rats have to do with us?” This study alone is
not a comprehensive revelation of the actual
effects caffeine has on the
human brain that cause
de l ayed matu rat i on.
Since the patterns in
t h e d eve l opme n t
o f n e u r o l o g i c a l
connections in rats
and human are very
similar, Huber’s results
most likely reflect similar
