Serotonin
and depression
Trevor Eddolls is convinced
they’re not linked
R
esearch shows that serotonin and
depression are not directly linked.
Everyone knows that low serotonin levels
cause depression – in much the same way
that everyone used to know that the Earth
was ?at! Everyone knows depression is
caused by low serotonin levels – in the
same way that everyone knows
that headaches are caused
The blood-brain barrier separates Brain
ExtraCellular Fluid (BECF) from circulating blood.
by a lack of paracetamol or
It consists of endothelial cells that restrict the
aspirin.
di?usion of microscopic objects and large or
hydrophilic molecules, but allow the di?usion
of small hydrophobic molecules (O2, CO2,
hormones). Glucose and speci?c proteins are
actively transported across the barrier.
The trouble is that many people
believe there is a direct link
between neurotransmitter serotonin
levels and depression, and many
hypnotherapists are saying this to
their clients. According to Ben Goldacre in Bad
Pharma: “The ‘serotonin hypothesis’ for depression,
as it is known, was always shaky, and the evidence
now is hugely contradictory”.
Most drugs used for depression are SSRIs –
selective serotonin reuptake inhibitors – yet Goldacre
informs us that tianeptin is equally e?ective, and it
18 Hypnotherapy Today
is a selective serotonin reuptake ENHANCER. It
should have quite the reverse e?ect, if the theory
held water.
Why is it so hard to prove this one way or another
– either serotonin levels e?ect depression or they
don’t. It’s hard because scientists would have to work
on living brains, and not many people would agree to
have part of their brain mashed up for science (and
those darn ethics committees wouldn’t be very happy
either!). The only way the science can be done is by
measuring serotonin levels in blood. You can see the
problem. Serotonin is a neurotransmitter, it exists
in the synapses between neurons. There’s a bloodbrain barrier that stops large molecules di?using in
or out. And serotonin is made in other parts of the
body too. It seems that about 90% of the serotonin
in our bodies is in what are called enterochroma?n
cells. These can be found in the gut and are used to
regulate intestinal movements.
Even allowing for these di?culties, scientists made
an estimate of the serotonin levels in the brains of
depressed people - and they found that they were
pretty much the same as the rest of us.
So, scientists tried another experiment. They took
normal healthy people and reduced their serotonin