Researchers are always looking for biomarkers of autism as a diagnostic tool; I am more interested in biomarkers as an indicator of might be going wrong and hence, perhaps, an indicator of what to do about it.
Going back
more than half a century, just such a biomarker was found. Increased platelet levels of 5-HT (5-Hydroxytryptophan) were found in 30-40% of the autistic
population. 5-HTP
increases the production of the neurotransmitter serotonin and so it was suggested
that hyperserotonemia may be a factor in autism.
Hyperseratonemia (Serotonin
syndrome)
Hyperseratonemia
is not treated by reducing the amount of serotonin, rather by using a receptor antagonist that in effect blocks the serotonin effect.
SSRIs and other anti-depressants
Several
classes of drugs target the 5-HT system including anti-depressants,
antipsychotics,
anxiolytics,
antiemetics,
and antimigraine
drugs, as well as the psychedelic
drugs and empathogens.
In you live
in the US, you will have heard of Prozac (vitamin P) which is a very widely
prescribed anti-depressant. It is in a
class of drug called Selective Serotonin
Re-uptake Inhibitors or SSRI. Many
autistic children in the US are prescribed SSRIs like Prozac. In Japan Prozac is illegal.
SSRIs are believed to increase the extracellular level of serotoinin by
inhibiting its reuptake. Excessive
use of SSRIs is known to lead to hyperseratonemia. If you are
already prone to hyperserotonemia, like 40%
of autistic kids, it would seem that SSRIs
could be potentially dangerous drugs.
A good deal
of research does exist on the use of SSRIs in autism and it pretty much shows
that they do not do much good, (and they certainly can have nasty side effects). Look at page 6, in the review paper below that
included all kinds of drugs trialled in autism.
LSD and other serotonin
antagonists
LSD is a
banned substance in the US and Europe, but in the time before I was born, it
was being used to treat autism. LSD,
among other things, is a serotonin antagonist.
There are indeed several papers published on its use in autism and other
conditions.
I was quite
surprised to see Ivaar Lovaas, the “father” of Applied Behavioural Analysis
(ABA) was merrily giving autistic children LSD at UCLA in the early 1960s.
These old
studies are quite interesting and if you want more just click here.
I am not
suggesting you take your child to Amsterdam, but if you look on Google you will
see that adults with ASD are indeed using LSD therapy.
It now
appears that after being banned from use decades ago, medical research with LSD
has been restarted.
Fortunately,
there are other serotonin antagonists that are available and will not land you
in trouble. The one that attracted my
attention is Cyproheptadine
or Periactin.
There has
been just one study published on autism and Cyproheptadine and that was in 2004.
It is not exactly what we need, since it was being trialed as an adjunct
therapy to haloperidol. Haloperidol is
an antipsychotic.
If you live in the US you will be familiar with Risperidone, which is
another antipsychotic shown to be effective in autism. In the UK, only specialists such as child psychiatrists can prescribe risperidone for children with autism. Risperidone can cause side effects like uncontrollable
shaking.
So the trial was
in effect to see the effect of the antipsychotic + Cyproheptadine vs
antipsychotic + placebo. This is not
exactly what we want, but better than nothing.
As you will see
in the charts below, the addition of Cyproheptadine did indeed make a marked
improvement. Sadly this research has not
been followed up on.
Serotonin and Emotional Response
There was a
recent study looking at how the emotional response of adults with autism was affected
by lowering serotonin levels, I could not find the full version.
Conclusion
Elevated
blood levels of serotonin may or may not be a “red herring” in autism
research. The evidence is far from
complete and it is not going to be a magic bullet. Nonetheless, I suspect lowering serotonin
levels may have far more impact than those expensive high EPA Omega 3 pills many
parents are feeding to their kids.
The latest
research does actually indicate that genetic differences cause the high levels of 5-HT in autism. 100% conclusive research does not exist
showing the value of counteracting this genetic difference. A safe, cheap, serotonin antagonist, Cyproheptadine /Periactin does exist; and it is available OTC in some countries.
Autism gene variant causes hyperserotonemia, serotonin receptor hypersensitivity, social impairment and repetitive behavior