Do Vaccines Cause Autism?

There’s nothing more scary for parents than the thought that they might hurt their children. The controversy about vaccines and autism is frightening, but seems to have little scientific backing.

It started in 1998. The Lancet reported on 12 children with gastrointestional problems that they believed were caused – at least partly – by vaccinations. They claimed those problems contributed to autism and other conditions in the children.

Initial research seemed to support their argument: Unusual levels of measles virus RNA (a type of DNA) was found in certain parts of the kid’s bodies. But on two levels their analysis was refuted: by massive analysis of hundreds of thousands of children and autism, and by carefully examining their scientific method.

Epidemiological studies

Massive amounts of evidence shows that the large increase in autism over the past few decades is not associated with vaccination.

One study in Denmark compared 500,000 children vaccinated against 100,000 who weren’t. They had pretty much the same chance of autism.

The measels, mumps and rubella (MMR) vaccine was started in 1988 in London and no correlation was found between that and an increase of autism. Additionally, the vaccination efforts initially were distributed in clusters: not everyone got it at once. No such cluster effect was found in autism rates.

Similar data show that introduction of MMR in Japan in 1993 was not correlated with increase in autism rates.  One thing is consistent: analysis of tens of thousands of kids shows again and again no risk for autism associated with vaccine use.

Refuting the science

How might vaccines cause autism? The most prominent theory was that they somehow trigged an “aberrant immune reaction” that caused damage to the brain. The gastrointestional upset, for instance, might allow toxic proteins to reach the brain that otherwise wouldn’t.

The evidence for this theory was that a few kids with autism had been shown to have measles virus RNA in parts of the body where they shouldn’t be, like inside certain blood cells.

Suspicion of this theory was raised when multiple other studies were unable to replicate the findings.

D’souza et al carefully analyzed the reports and showed that their results were most likely because of mistakes. Either because of false positives or because of mistakes in the lab with how the materials were dealt with.

Thimerosal

Another theorized problem was the presence of thimerosal in vaccines. Superficially, it seems insane to include it; it is, after all, mercury, and we all know how dangerous that is.

Thimerosal, however, is a specific type of mercury called ethyl mercury, which is biodegradable and does not cause toxic build up in the body. Similarly large epidemiological studies have shown that it is not associated with autism.

Finally, all vaccines are now available without thimerosal.

Conclusion

There is no denying that diagnoses of autism have really, really increased over the last few decades. But it’s hard to say why. Increased recognition must play a large part, as well as diagnosing milder cases that would have previously been ignored.

It is also possible that other environmental issues play a role.

Vaccines are extremely important to protect children from diseases.

Next Article: Treatments of Autism

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Sources:

Vaccines and Autism: Evidence Does Not Support a Causal Association
No Evidence of Persisting Measles Virus in Peripheral Blood Mononuclear Cells From Children With Autism Spectrum Disorder
Has the Measles-Mumps-Rubella Vaccine Been Fully Exonerated?

ADHD is most often treated by stimulants like Ritalin, Adderall, and Dexedrine. I’m sure you’ve heard of these medications – but what are they? What do they do?

And most importantly – are they safe?

Are Stimulants Safe?

Stimulants are powerful medications, potentially addictive, and can have very serious side effects.

They’re commonly used because they’re effective.  Up to 70% of people experience significant symptom relief on them.  And the majority of the millions of people who use them are fine.  But they do have common side effects, and can rarely cause some quite nasty things.

The most common issues with stimulant use include increased anxiety, nausea or loss of appetite, and insomnia.

The rarer and very serious side effects?  To quote an ad for Vyvanse, an ADHD medication, “new psychosis, mania, aggression, growth suppression and visual disturbances” are possible.

Heart Damage?

Stimulant use might cause heart damage over time. Stimulants typically increase heart rate by ~3-5 beats per minute and also raise blood pressure.  One study of more than 50,000 children using stimulants showed an 20% increase in risk of emergency treatment for heart problems.

Use of stimulants by someone with a preexisting heart condition is a big no-no, as they may increase risk of cardiac failure or sudden death.

Psychological problems

As mentioned, a rare but serious side effect is that stimulants can cause psychosis, or a break with reality such as paranoia, delusional thinking and hallucinations.  Most psychosis occurs in people who were already at risk – but stimulants can cause psychosis in normal people at normal doses.

Stimulants can also cause serious problems with regulating or controlling mood. They can trigger mania in bipolar patients, and cause extreme mood variation even in people not normally at risk for bipolar.

Stimulants change the brain

Do stimulants cause brain damage?  Maybe.

Studies in rats have shown that extremely high doses of amphetamines given over a short period of time cause serious damage to the production of dopamine and its transport in the brain.  This happens by causing build up of radicals and reactive oxygen species.  Methylphenidate, or Ritalin, does not cause this damage, possibly because it only blocks the receptors for reception of dopamine.

But what about normal use?

The rats did not experience neural changes or damage from doses in the normal range.  The news isn’t all good, though. Baboons and monkeys, however, did experience brain damage at normal doses, showing a significant reduction in natural production and handling of dopamine.

It’s not clear what this means.  Children who take ADHD medication, after all, have larger white brain matter than unmedicated children, indicating a neuro-positive effect.

Remember: use of stimulants in children requires extreme caution and psychological analysis because they are young, more susceptible to side effects, and still developing.

Do stimulants like Adderall and Ritalin stunt growth?

This question is extremely contentious. A number of studies have shown that stimulant use is associated with slightly reduced growth, and, on the other hand, a number have shown that they aren’t.

The evidence, in my opinion, seems to be in favor of a slight reduction in height associated with long term use.

Both sides agree  that stimulant use initially slows growth somewhat; the question is if that delay is made up for in the long run.

Stimulant use is, however, associated with some degree of weight loss in the long run.

Conclusion:

Stimulants are extremely commonly used for a reason. They work. That said, they are potent substances, and often require supportive psychological therapy on the side to achieve best results.

For someone with a history of anxiety or other psychological problems, or someone with cardiac issues, use of stimulants should be exceptionally cautious if at all.  Use in children should also be done with extreme caution and only after appropriate psychological evaluation.

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Sources:

Potential Adverse Effects of Amphetamine Treatment on Brain and Behavior: A Review
Comparative Efficacy of Adderall and Methylphenidate in Attention-deficit/Hyperactivity Disorder: A Meta-Analysis
Cardiac Safety of Methylphenidate Versus Amphetamine Salts in the Treatment of ADHD