Today’s post is about cholesterol, statins and autism. There is a well-documented condition associated with autism called SLOS (Smith-Lemli-Opitz Syndrome). It is caused by mutations in the DHCR7 gene encoding the enzyme that catalyzes the final step in cholesterol biosynthesis.
Toe syndactyly (webbed toes), one symptom of SLOS
Reduced activity of the enzyme 7DHCR typically leads to low levels of cholesterol, but markedly increased levels of precursor 7DHC (and its isomer, 8DHC) in blood and tissues. Typical SLOS manifestations include intellectual disability, growth retardation, minor craniofacial anomalies, microcephaly and 2-3 toe syndactyly (webbed toes).
SLOS is rare, but some cases do get missed because you can have a DHCR7 mutation and have normal levels of cholesterol and have normal cognitive function.
Cholesterol and the blood brain barrier (BBB)
You do have a lot of cholesterol in your brain, but it does not cross the blood brain barrier (BBB), it was made in the brain. Eating more cholesterol can have no direct effect on cholesterol levels in the brain.
The standard treatment for SLOS has long been oral cholesterol supplementation, but there is no conclusive research to show it helps. There is plenty of anecdotal evidence.
Simvastatin and SLOS
Simvastatin is a drug widely used drug to treat people with elevated cholesterol.
There has been anecdotal evidence that Simvastatin improves SLOS and recently a very thorough study was carried out to establish whether or not it really has a benefit.
In reality the study was comparing:
Simvastatin + cholesterol supplement vs cholesterol supplement
The study was carried out by researchers including Dr Richard Kelley (“Dr Mitochondria”) and Dr Elaine Tierney (“Dr Cholesterol”)
Currently, most SLOS patients are treated with dietary cholesterol supplementation. Although cholesterol therapy reduces serum 7-DHC concentrations to a degree, significant amounts of 7-DHC persist even after years of therapy. Anecdotal case studies and case series support the idea that cholesterol supplementation benefits the overall well-being of SLOS patients; however, the effects of dietary cholesterol supplementation on cognitive or behavioral aspects of this disorder have not been reported by others or substantiated in a limited controlled trial. The efficacy of dietary cholesterol supplementation is probably limited by the inability of dietary cholesterol to cross the blood–brain barrier. Moreover, increased concentrations of 7-DHC or 7-DHC-derived oxysterol could have toxic effects. Specialists have hypothesized that, in patients with mild to classic SLOS, many aspects of the abnormal behavioral and cognitive phenotype could be the result of altered sterol composition in the central nervous system. Thus, interventions that ameliorate the central nervous system biochemical disturbances in SLOS are critical to understanding the pathological processes that underlie this inborn error of cholesterol synthesis and to developing effective therapies to treat the neurological deficits.
Expression of DHCR7 is regulated by SREBP2, which, when activated by low levels of cholesterol in the endoplasmic reticulum, increases the transcription of most genes of the cholesterol synthetic pathway. Having shown that DHCR7 expression is increased in SLOS fibroblasts treated with simvastatin,31 we hypothesized that the paradoxical increase in serum cholesterol could be the result of increased expression of a DHCR7 allele with residual enzymatic function, and we demonstrated that many DHCR7 alleles encode an enzyme with residual activity. Furthermore, both in vitro experiments with human fibroblasts and in vivo experiments using hypomorphic Dhcr7T93M/delta mice support the hypothesis that increased expression of DHCR7 alleles with residual enzymatic activity can significantly improve plasma and tissue sterol concentrations. Because residual DHCR7 activity varies among patients with SLOS, this hypothesis could explain the paradoxical increase in cholesterol in some patients and the adverse reactions observed in others.
In this study we also evaluated the potential of simvastatin to alter specific aspects of the SLOS behavioral phenotype. Our secondary outcome measures were the CGI-I and ABC-C irritability scores. Although we observed no significant effect on the CGI-I, we did observe significant improvement in the ABC-C irritability score (Figure 4). This article therefore represents the first controlled study to demonstrate improved behavior in subjects with SLOS in response to a therapeutic intervention.
In summary, this study represents the first controlled trial of simvastatin therapy in SLOS and the first controlled trial demonstrating the potential of drug therapy to modulate sterol composition and to improve behavior in SLOS. We have established that treatment with simvastatin is relatively safe, can decrease DHC levels, and can improve at least one aspect of the behavioral phenotype. These data support continued efforts to identify and rigorously evaluate potential therapies that may have clinically meaningful benefits for patients with SLOS.
Plasma sterol levels
Cholesterol and dehydrocholesterol (7DHC + 8DHC) levels were measured at baseline (B), washout (W, 14 mo) as well as at 1, 3, 6, 9 and 12 months in both the placebo and simvastatin treatment phase. Plasma cholesterol levels (A, B) and DHC (C, D) decreased significantly during the simvastatin phase compared to the placebo phase. The plasma DHC/Total Sterol ratio (E, F), which was the primary outcome measure of this study, also decreased significantly. Data expressed as mean ± SEM.
Hypocholesterolemia (low cholesterol) and some Autism
Ten years ago, Tierney and Kelley published research showing that about 20% of autism is associated with very low cholesterol levels (less than the 5th centile for typical young people) but in their sample of 100, none had an abnormally increased level of 7DHC consistent with the diagnosis of SLOS or abnormal level of any other sterol precursor of cholesterol.
Tierney went on to patent cholesterol as a therapy for autism.
The present invention relates to the field of autism. More specifically, the present invention provides methods for treating individuals with autism spectrum disorder. Accordingly, in one aspect, the present invention provides methods for treating patients with autism spectrum disorder. In one embodiment, a method for treating an autism spectrum disorder (ASD) in a patient comprises the step of administering a therapeutically effective amount of cholesterol to the patient. In more specific embodiments, the ASD is autism, Asperger's disorder, pervasive developmental disorder-not otherwise specified (PDD-NOS), Rett's syndrome and childhood disintegrative disorder. In one embodiment, the patient has autism.
Tierney has a clinical trial registered that was to start in 2009.
Three sites (Kennedy Krieger Institute [KKI], Ohio State University [OSU], and the National Institutes of Health [NIH]) will collaborate to accomplish the objectives of this study. In addition to defining the frequency of altered cholesterol homeostasis in ASD, 60 youths (20 at each site) with ASD plus hypocholesterolemia will enter a 12-week, double-blind, placebo-controlled trial immediately followed by a 12-week open-label cholesterol trial to test the efficacy of dietary cholesterol supplementation. Outcome measures will include standard tests of behavior, communication, and other autism features.
It appears that the study has not been completed.
Dr. Elaine Tierney and her colleagues are studying different metabolic disorders that can present with autism spectrum disorder through the Autism Metabolic Research Program at Kennedy Krieger. In 2000 and 2001, this group of researchers identified that Smith-Lemli-Opitz-Syndrome (SLOS) is associated with autism spectrum disorder. Since SLOS is known to be caused by a defect in the body's biosynthesis of cholesterol, SLOS may provide clues to the biochemistry of other autism spectrum disorders (ASD).
Dr. Tierney and colleagues published a paper in 2006, in the American Journal of Medical Genetics Part B (Neuropsychiatric Genetics), in which they describe finding that a subgroup of children with ASD have abnormally low cholesterol levels. The children's low cholesterol levels were apparently due to a limited ability to make cholesterol. This finding, in concert with their work with SLOS, has led them to believe that cholesterol may play a role in the cause of some cases of autism spectrum disorder. Dr. Tierney and colleagues at Kennedy Krieger, the National Institutes of Health and Ohio State University are performing a double-blind placebo-controlled study of cholesterol in individuals with ASD.
Cholesterol as a marker of inflammation
Nowadays, hypercholesterolemia and inflammation are considered as “partners in crime”. Statins do lower bad cholesterol, but they also have broad anti-inflammatory effects.
Atherogenesis in perspective: Hypercholesterolemia and inflammation as partners in crime
A historical perspective on atherosclerosis allows us to reflect on the once controversial hypotheses in the field. Plaque formation was once thought to be dependent upon hypercholesterolemia alone, or solely in response to injury. More recently, inflammatory cascades were thought to be at the root of lesion development. A more realistic view may be that atherosclerosis is neither exclusively an inflammatory disease nor solely a lipid disorder: it is both.
A historical perspective on atherosclerosis allows us to reflect on the once controversial hypotheses in the field. Plaque formation was once thought to be dependent upon hypercholesterolemia alone, or solely in response to injury. More recently, inflammatory cascades were thought to be at the root of lesion development. A more realistic view may be that atherosclerosis is neither exclusively an inflammatory disease nor solely a lipid disorder: it is both.
An altered immune response is a feature of many people’s autism, and you can measure it.
As Paul Ashwood’s research has shown, there are different immune sub-groups that people with autism fall into, and so you could treat each cluster with a specific therapy.
Cholesterol and Thyroid Hormones
Your thyroid produces hormones that control your metabolism. Metabolism is the process your body uses to convert food and oxygen into energy.
Your body converts the circulating pro-hormone T4 into the active hormone T3 locally. So, in your brain T4 has to be converted to T3. If you lack enough T4 coming from your thyroid gland or the special enzyme called D2 you are going to feel lethargic.
Your body needs thyroid hormones to make cholesterol and to get rid of the cholesterol it doesn’t need. When thyroid hormone levels are low (hypothyroidism), your body doesn’t break down and remove LDL (“bad”) cholesterol as efficiently as usual. Elevated LDL cholesterol will show up in your blood tests.
Hyperthyroidism has the opposite effect on cholesterol. It causes cholesterol levels to drop to abnormally low levels.
So best to check thyroid function and cholesterol levels.
Conclusion
My main interest is autism with a tendency to big heads (hyperactive growth signalling pathways) and an overactive immune system. This is the opposite of SLOS and hypocholesterolemia (low cholesterol).
For the 20% with low cholesterol, I think this is a very important biomarker.
Hopefully one day soon Dr Tierney, at Kennedy Krieger, will publish her results of cholesterol as a therapy for people with autism and low cholesterol.
For me it is good to see that Simvastatin was well tolerated in a 12 month long trial in children from 4 to 18 years of age. I have the very similar drug, Atorvastatin, in my Polypill.
Interestingly, in a paper that I will cover in later post, increasing HDL (good cholesterol), a feature of Atorvastatin and Simvastatin, was one marker of behavioral improvement in the Ketogenic Diet.
