Long term smoking contributes to cognitive declineBMJ 2004; 329 doi: https://doi.org/10.1136/bmj.329.7478.1306 (Published 02 December 2004) Cite this as: BMJ 2004;329:1306
All rapid responses
It is my hypothesis that all drugs of abuse, including nicotine,
exert effects that ultimately stimulate DHEA production. Nicotine
stimulates production of DHEA sulfate (DHEAS), the large background source
of DHEA, the active molecule. This effect reduces stimulation by DHEA; it
relaxes. However, ultimately DHEA is converted from this increased DHEAS,
thus increasing DHEA stimulation. I suggest this affects the pleasure
centers and other parts of the brain; the relaxation may produce the
pleasure and the restimulation of increased DHEA then resets the pleasure
center or other brain part. (This simple mechanism may explain addiction
and tolerance of drugs of abuse.)
It is also my hypothesis that DHEA positively affects brain function
(as well as all tissues). Therefore, smoking, nicotine, increases brain
function overall, not just resetting pleasure centers. (Increased DHEA
increases mental abilities; nicotine ultimately increses DHEA.) So, I
suggest a certain amount of individuals who smoke, do so to increase their
abilities to function in various aspects of life. (Some students smoke to
improve concentration, etc.) This group is probably naturally low in
DHEA. This may be why the effects of nicotine are so attractive to them.
They literally lead "better" lives because of this effect for a time.
Since these individuals produce less DHEA, and use of nicotine may
shorten their life span production of DHEA because of the increased
stimulation of DHEAS resources, there are consequences. DHEA naturally
begins to decline around age twenty, reaching very low levels in old age.
The accelerated use of the life span's ability to produce DHEAS and DHEA
by nicotine, in essense, accelerates aging also. Therefore, the mental
abilities of these individuals are "aged" earlier. Therefore, their IQs
and cognitive abilities at age 64 will be more characteristic of later
age. I suggest the negative long term effects of smoking on cognitive
abilities are the result of premature aging which results from nicotine-
stimulated DHEAS and DHEA production over the life span. It is also my
hypothesis that reduced DHEA may trigger cancer oncogene initiation.
(Cancer initiation occurs more often in old age, low DHEA, than young
age.) This may be why many develop cancer while some do not, that is,
those who do not carry oncogenes.
Competing interests: No competing interests