Susan Lucca used to be known
as the Scrabble queen in her family. However, since being
diagnosed with breast cancer, this 47-year-old English
teacher's game scores have declined as quickly as her
health. Her doctor suggested that this was likely due
to stress, but Mrs Lucca feels there may be something
more than that going on. 'Chemobrain,' a decline in cognitive
function in people undergoing cancer treatment, is a known
risk of chemotherapy. But some cancer patients, like Mrs
Lucca, have also reported cognitive decline even before
starting treatment.
Chemo
not the culprit
A study published in the June 21 issue of Cancer
suggests that Susan Lucca's instincts were right
after all. In a significant minority of patients, there
is evidence of loss of function in learning and memory
that appears to be related to the cancer itself.
The research, conducted at the
University of Texas in Houston measured cognitive decline
in female breast cancer patients before and after treatment.
Of 84 test subjects, one-third suffered an abnormal
drop in verbal learning and memory functions before
beginning chemotherapy. The authors say these impairments
fall outside the normal range based on the patients'
age, education and employment history.
What's causing the decline remains
a mystery but there are some theories. "Hormonal status
may reduce a cognitive reserve, which may be associated
with greater risk for suffering from adverse symptoms
but we really don't know," says lead author Christina
Meyers, PhD and professor of neuropsychology at the
University of Texas.
There's some circumstantial evidence
that hormones like estrogen are involved in the mental
deficit. For instance, the patients who suffered cognitive
decline before starting chemo tended to have undergone
more invasive surgery for their cancer. They were also
more likely to be postmenopausal, and less likely to
have taken hormone replacement therapy.
Different
states of mind
Even so, the researchers are reluctant to pin the blame
exclusively on estrogen, because they've observed similar
trends in a group of male lung cancer patients. They
suspect that the cancer is causing a systemic immune
inflammatory response in certain predisposed people.
Other studies have examined the
chemobrain phenomenon, but this is the first to look
at pre-treatment cognitive decline. Identifying cases
where brain power drops off before chemotherapy helps
to isolate those whose cognitive decline is really due
to this treatment. So far, only 18 patients have been
measured for both pre-treatment decline and chemobrain.
Of these, one-third experienced pre-treatment decline,
and more than half showed evidence of chemobrain. There
was no correlation between the two groups --those
whose cognitive function was affected by the disease
itself had no increased tendency for further impairment
from the treatment. This suggests that these are two
separate events with two different mechanisms at work.
Half of the chemobrain sufferers had regained some cognitive
function one year after treatment. It's not yet known
whether the disease-associated losses are also reversible.
Professor Meyers said patients
with cognitive losses mostly already knew something
was wrong and appreciated knowing that there is a biological
explanation -- however mysterious. "These losses
are not due to emotions or anxiety, and patients are
grateful when it is recognized. We want them to know
that we are trying to understand why this happens and
that there are a wide variety of therapies available
to help them."
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