with colds reported less alertness, more negative moods and
sluggish thinking. A second round of tests showed they also
had slower reaction times and were slower at learning new
information and completing tasks involving verbal reasoning
and semantic processing (Brain, Behavior, and Immunity,
Research suggests that cold viruses cause sluggishness
by interfering with neurotransmitters, perhaps affecting
the transmission of noradrenaline, choline and dopamine.
Noradrenaline is associated with reaction times. Choline
has been linked to the encoding of new information, while
dopamine affects working memory speed.
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Previous studies have found that cognitive impairment can
occur for people with infections from cold viruses even if they
have no physical symptoms and that their decline in alertness
can have serious consequences. Smith also conducted a study
of 15 participants with colds and 10 healthy participants who
completed a simulated driving task. Those with colds responded
more slowly to unexpected events on the road and were less
likely to detect collisions (BMJ Open, 2012). Another study,
commissioned by Lloyds TSB Insurance, estimated that in 2008,
more than 125,000 accidents in Great Britain were caused by
drivers who had a cold or the flu.