Research & Education

Autism and Cerebral Folate Deficiency


I work with a family with two young sons both diagnosed with autism. They live in a large West Coast city. No one else in their immediate or extended family has an Autistic Spectrum Disorder (ASD) or autoimmune disorder (the latter is sometimes associated with ASD). Understandably one of the first questions the father of these two boys asked me was Why do my sons have autism? It's a heartbreaking question that any physician wants to be able to answer with surety but there are many potential contributing antecedents triggers and mediators.

One thing is certain howeverenvironmental exposures play a massive role in autism spectrum disorders given the meteoric rise in incidence since the 1980s.

The boys in this family are first generation Americans. This fact provides us with a unique window because Mom and Dad were born in and spent their earliest years in the Middle East with different environmental exposures. The parents recall that the older son developed ASD very early on before the usual 18-24 month timeframe commonly seen today. Despite their best efforts it took some time before he was given the correct diagnosis and treatments were started.  Because of the later treatment start he didn't respond to biomedical and behavioral interventions as well as his younger brother. With their second son both parents spotted the signs of autism immediately and initiated treatment. He responded very well and demonstrates fewer autistic features today.

One key intervention for both boys that resulted in a significant reduction of behavioral symptoms was the removal of bovine dairy and gluten-containing grains. Both are big problems for many kids with ASD and their removal is a common first step.

The older boy recently started a trial of high-dose folinic acid (1mg/kg body weight). This intervention appears to have made a remarkable difference in him. Both parents noted that rather quickly after starting his expressive language greatly improved he began articulating his needs and desires in a way he's never done before. (In all fairness we cannot rule out benefit from his various other treatments. This trial like life wasn't controlled.)

Given the above history and the favorable folinic acid trial is it possible for us to form a hypothesis around a potential causative factor in this case? Yes we can.

I strongly suspect that Cerebral Folate Deficiency is an underlying etiologic factor with these boys. Here's why:

CFD was characterized a mere 10 years ago by Ramaekers et al.1 They describe five patients with normal development until approximately six months of age when developmental regression irritability psychomotor retardation ataxia  and other problems developed. Central nervous system 5-methyltetrahydrofolate (5-MTHF) levels were found to be very low although serum and RBC 5-MTHF were normal. The patients responded favorably to the addition of folinic acid.

Ramaeker's group later investigated mutations in a blood-brain barrier folate-transport-associated protein (folate receptor 1 or FR1) and found none. They did however find high affinity autoantibodies to FR1 in a group of 25 children with CFD.23

Research by other groups found an association of CFD and a wide variety of mitochondrial diseases (MD). Individuals with MD/CFD may not apparently have FR1 autoantibodies. 4-8

Further research found that a subset of individuals diagnosed with autism had either MD-associated CFD or FR1 autoantibody-associated CFD.239

Ramaeker identified in 2008 that human folate receptors potently cross react with folate receptors found in bovine or goat's milk. They noted that a dairy-free diet reduced production of FR1 autoantibodies.10 It was also observed that folic acid (also called synthetic oxidized or unmetabolized folic acid {UMFA}) competes with natural folates for the binding site on FR1. Not surprisingly folic acid is toxic to those with CFD associated with seizures and symptom regression.211

The fact that so many individuals with ASD respond very favorably with the removal of dairy from their diet is an interesting correlation. Do these children have CFD? Is the action of removing dairy allowing increased transport of active folates into the central nervous system? And likewise is the removal of gluten-containing grains (which yields clinical improvement for many) reducing exposure to synthetic folic acid? All very valid questions.

Monitoring UMFA in the serum of individuals with diagnosed or suspected CFD could make good sense given the ubiquitous presence of synthetic folic acid in the food supply and its toxic ramifications in those with CFD. My goal for these individuals would be to minimize the presence of UMFA in the serum not unlike anti-gliadin antibodies in celiac patients.

Now back to the case study:

It's compelling that Mom and Dad both spent their early years in a country that didn't participate in folic acid enrichment (Egypt). Additionally the father reports ingesting less cow's dairy prior to coming to the West. However both boys were born and raised in the West on a diet deemed healthy by most which invariably includes much synthetic folic acid and dairy. Both boys developed autism. Both developed it earlier than the commonly seen 18-to-24-month window which fits Ramaeker's description. Both boys responded favorably to the removal of dairy and gluten. Since the younger son's treatment started earlier he demonstrated a fuller resolution as presumptively his CNS folate levels were restored sooner.

If these boys have CFD we'd expect something like this would we not? The youngest boy does well because both toxic components to CNS folate transport dairy and synthetic folic acid have been removed very early on in his development. The older boy's favorable response to folinic acid a bioidentical folate seems apparent. There is no history of such problems in this family because there is no previous exposure to these elements in the same way.

I would argue that a careful monitored therapeutic trial with folinic acid is indicated for most children on the spectrum regardless of whether they fit the pattern of the boys in this case or not. Mitochondropathy is very common in this population and is also an underlying factor for CFD. Interestingly the boys in my case didn't have the classic pattern of mitochondropathy on laboratory analysis (learn about testing for mitochondrial dysfunction and other imbalances using organic acids here).   

Next treatment steps: Check serum UMFA levels in both boys (and anyone with ASD or suspected CFD.) Consider a trial of folinic acid for the younger boy as he continues to have some autistic features. If the boys have higher serum UMFA I would strongly suggest to the parents that we investigate the occult exposure sources and remove them. 

Many questions remain regarding CFD and autism and the impact of folic acid dairy gluten and the myriad environmental toxins we are all exposed to daily. Of course folic acid fortification has reduced the incidence of birth defects in this country and others. No one however metabolizes synthetic folic acid into its active counterparts very efficiently. And some of us activate it much more slowly allowing for a pronounced accumulation and increasing vulnerability to toxicity.121

by Dr. Kara Fitzgerald



Dr. Fitzgerald received her doctorate of naturopathic medicine from National College of Natural Medicine in Portland Oregon. She completed the first CNME-accredited post-doctorate position in nutritional biochemistry and laboratory science at Metametrix Clinical Laboratory under the direction of Richard Lord Ph.D. Her residency was completed at Progressive Medical Center a large integrative medical practice in Atlanta Georgia. Dr. Fitzgerald is lead author and editor with J. Alexander Bralley Ph.D. of The Metametrix Institute's Case Studies in Integrative and Functional Medicine. She is a contributing author to Laboratory Evaluations for Integrative and Functional Medicine and the Institute for Functional Medicine's updated Textbook for Functional Medicine. She has also published in a number of peer reviewed journals. Dr. Fitzgerald is on faculty and a Curriculum Advisory Committee member at Institute for Functional Medicine. She is an adjunct faculty member at University of Bridgeport in the school of Human Nutrition and a member of The Institute for Therapeutic Discovery. Dr. Fitzgerald regularly lectures internationally for several organizations. Formerly at Advanced Diagnostic Pain Treatment Center at Yale-New Haven she is now in private practice in Sandy Hook Connecticut. She may be reached at or



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