- NEW YORK (Reuters
Health)- Caffeine may affect the process of long-term memory by changing
the structure of dendritic spines, tiny "branches'' found on nerve
cells in the central nervous system.
- According to Drs. E. Korkotian and Menahem Segal of The
Weizmann Institute in Rehovot, Israel, scientists have assumed that changes
in the size and shape of these dendritic spines are related to long-term
memory, but there has not been any experimental evidence to prove this
association. In a new study reported in the Proceedings of the National
Academy of Sciences, the Israeli researchers show that when caffeine is
added to the cells, the dendrites not only grow longer, but also develop
new spines or branches.
- Korkotian and Segal studied cells from the hippocampus,
a part of the brain that plays an important role in learning and memory.
When left alone without stimulation, the cells did not do anything at all
over a 3- to 4-hour period. But adding caffeine to the cells raised the
level of calcium inside them, causing them to grow about 33% in size. Calcium
is an important factor in signal transmission or cellular communication
in the brain.
- Previous laboratory studies had found that raising the
calcium levels in dendritic cells caused them to collapse. Korkotian and
Segal suggest that the difference in findings may be that in the previous
studies, adding glutamate cause more calcium to enter the cells, while
adding caffeine caused the cells to release their stored calcium.
- Also, the researchers add, glutamate causes a much larger
increase in calcium inside the cells, while caffeine produces a more moderate
- These findings suggest that stored calcium "may
be even more important than originally proposed'' in the process of increasing
calcium in these central nervous system cells, noted the authors.
- The investigators also found that new spines tended to
grow on parts of the cells that already had lots of spines, rather than
in areas where there were not many spines at all.
- The findings point to a need for further research into
these processes, since they suggest that a modest, temporary rise in calcium
levels results in growth and proliferation of these important brain cells,
while a larger and more prolonged rise causes the cells to collapse. The
implications for long-term memory and learning are not yet clear.