Source: University of Birmingham
Summary: Scientists have uncovered a possible
explanation for the mental sluggishness that often accompanies illness.
Scientists at the University of Birmingham in
collaboration with the University of Amsterdam have uncovered a possible
explanation for the mental sluggishness that often accompanies illness.
An estimated 12M UK citizens have a chronic
medical condition, and many of them report severe mental fatigue that they
characterize as 'sluggishness' or 'brain fog'. This condition is often as
debilitating as the disease itself.
A team in the University's Centre for Human
Brain Health investigated the link between this mental fog and inflammation --
the body's response to illness. In a study published in Neuroimage, they show
that inflammation appears to have a particular negative impact on the brain's
readiness to reach and maintain an alert state.
Dr Ali Mazaheri and Professor Jane Raymond of
the University's Centre for Human Brain Health, are the senior authors of the
study. Dr Mazaheri says: "Scientists have long suspected a link between
inflammation and cognition, but it is very difficult to be clear about the
cause and effect. For example, people living with a medical condition or being
very overweight might complain of cognitive impairment, but it's hard to tell
if that's due to the inflammation associated with these conditions or if there
are other reasons."
"Our research has identified a specific
critical process within the brain that is clearly affected when inflammation is
present."
The study focussed specifically on an area of
the brain which is responsible for visual attention. A group of 20 young male
volunteers took part and received a salmonella typhoid vaccine that causes
temporary inflammation but has few other side effects. They were tested for
cognitive responses to simple images on a computer screen a few hours after the
injection so that their ability to control attention could be measured. Brain
activity was measured while they performed the attention tests.
On a different day, either before or after,
they received an injection with water (a placebo) and did the same attention
tests. On each test day they were unaware of which injection they had received.
Their inflammation state was measured by analysing blood taken on each day.
The tests used in the study assessed three
separate attention processes, each involving distinct parts of the brain. These
processes are: "alerting" which involves reaching and maintaining an
alert state; "orienting" which involves selecting and prioritising useful
sensory information; and "executive control" used to resolving what
to pay attention to when available information is conflicting.
The results showed that inflammation
specifically affected brain activity related to staying alert, while the other
attention processes appeared unaffected by inflammation.
"These results show quite clearly that
there's a very specific part of the brain network that's affected by
inflammation," says Dr Mazaheri. "This could explain 'brain
fog'."
Professor Raymond says, "This research
finding is major step forward in understanding the links between physical,
cognitive, and mental health and tells us that even the mildest of illnesses
may reduce alertness."
Dr Leonie Balter the first author of the study
which was completed as part of her PhD, concluded : "Getting a better
understanding of the relationships between inflammation and brain function will
help us investigate other ways to treat some of these conditions. For example,
further research might show that patients with conditions associated with
chronic inflammation, such as obesity, kidney disease or Alzheimer's, could
benefit from taking anti-inflammatory drugs to help preserve or improve
cognitive function."
"Furthermore, subtle changes in brain
function may be used as an early marker cognitive deterioration in patients
with inflammatory diseases."
The next step for the team will be to test
the effects of inflammation on other areas of brain function such as memory.
Story Source:
Materials provided by University of
Birmingham.
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