Most smokers are well aware of
the many effects that smoking brings with it; these usually extend to
respiratory and cardiovascular areas. However, a recent study from Kings
College London now claims that smoking may even affect cognitive function such
as memory, learning and reasoning.
The study, which was published in
Journal of Age and Ageing, was a
population based cohort study and included a total of 8850 participants over
the age of 50. The participants were classified as either non-smokers or
current smokers (with ex-smokers being categorised as non-smokers). The
researchers carried out several surveys regarding health and lifestyle. In
addition to that, the participants took part in several cognitive tests where
it was required that they learn new words and name as many animals as they
could think of in one minute. The participants were followed up four years and
eight years since the initial testing and they provided the same data and did
the same tests, which were then compared. The findings indicated that there was
a consistent relationship between smoking status and poorer performance in the
cognitive tests. This led the researchers to suggest that smoking may be a risk
factor for affecting cognitive function in later life.
This study benefits from the
substantial sample size and the extensive questionnaires that provided
information on many aspects that could affect cognitive performance. This
included highest educational attainment, level of physical exercise, depressive
symptoms and age. Although the psychological tests may appear rather
rudimentary, they do in fact have a history of providing reliable and valid
results. What is interesting is that the cognitive decline reached
statistically significant levels, as it could be argued that participants
should have performed better in later tests as a result of learning what is
expected of them.
However, there are several
aspects of the study that make it challenging to directly apply the results to
smoking as a key factor on its own. Firstly, it is unfortunate that smoking
status was not more nuanced to separate the groups into ex-smokers, smokers and
non-smokers and individuals extensively exposed to second hand smoking. It also
appears that amount of smoking was not recorded, which would have been useful
to consider dose-response relationships between smoking and cognitive decline.
The study had sound theoretical basis as the relationship between
cardiovascular risk factors and cognitive decline appears to have been proposed
in the past and the relationship between smoking and cardiovascular health is
not novel within research to date. However, this study cannot pinpoint if and
how these may interact, or whether there is an alternative explanation that
would turn both cardiovascular risk factors and smoking into mediators.
Nevertheless, the study adds
weight to previous findings from limited studies that have considered the
potential relationships between smoking and cognitive function. It does have a
place in research for this particular demographic group and may be valuable in
further considering how smoking might affect the mind.
We are not surprised that smoking
affects both mind and body, as we often mention how complex the process of smoking
cessation can be. But what fascinates us about this study is that smoking has
been applied to specific cognitive functions that are valuable in an everyday
life. Although the findings need to be interpreted with caution, it is still
worth mentioning that smoking is a risk factor that individuals can affect and
that we encourage cessation sooner rather than later.