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Study links Chronic Epilepsy to lower brain cell production

13 January, 2005

A new study has
shown that chronic (recurrent or long-term) seizures decrease the
production of brain cells in the hippocampus, the brain's learning and
memory centre.

Epilepsy
has been believed to boost production of new brain cells as a means of
repairing injury, but this study is the first to demonstrate how new
brain cell production in the hippocampus is affected by chronic, rather
than acute (infrequent but severe), seizures.

In this study by researchers from Duke University Medical Center and the Durham VA Medical Center,
rats with chronic epilepsy showed a 75 per cent decrease in new brain
cell production in the hippocampus compared to the control group.

Lead
researcher Professor Ashok Shetty said that the finding explains why
people with chronic epilepsy are prone to learning and memory deficits
and depression and said that this new knowledge of brain cells in
chronic epilepsy could lead to treatments that alleviate the learning
and memory deficits and mood symptoms that can accompany the condition.

Professor Shetty commented:

"In
the future, we could theoretically treat chronically epileptic patients
with stem cell factors that induce new neuron [brain cell] production
and see if it alleviates their learning and memory problems and
depression; or we could prescribe exercise, enriched environment or
anti-depressants. All of these treatments are known to considerably
increase adult brain cell growth in the hippocampus where learning,
memory and mood are regulated."

In the study, published in the journal Neurobiology of Disease,
rats were induced to have seizures and hippocampal injury to mimic
humans with temporal lobe epilepsy. Immediately following the acute
seizures, there was a 60 per cent increase in new brain cell production
in the hippocampus. A respite period with no seizures lasted for four
to six weeks, and then seizures recurred with increasing severity - the
chronic phase of temporal lobe epilepsy. During the chronic phase, rats
displayed an average 75 per cent decrease in brain cell production.

The
study showed that the more frequent the rats' seizures, the fewer new
brain cells they produced in the long term and the fewer brain cells
their brains produced, the more likely they were to suffer more
seizures.

Professor Shetty added:

"With
chronic epilepsy, the brain's wiring is reorganized to become more
excitable. The seizures induce changes in nerve cells that make them
more susceptible to additional seizures."

The
rapid production of new nerve cells following acute seizures was
thought to repair damage, however, the study indicates that such rapid
brain cell growth actually dispatches cells to the wrong places and
contributes to abnormal brain circuitry.