Cerebral Folate Deficiency (CFD) is a medical condition where the brain does not get enough folate (vitamin B9), an essential vitamin for growth and development. What makes CFD tricky is that children may have normal folate levels in their blood, but the brain still isn’t getting enough. 

Folate is especially important for healthy brain development, communication between brain cells, and protecting the nervous system. When the brain doesn’t have enough folate, children may struggle with learning, development, or behavior.  

Leucovorin, or folinic acid, is the most common treatment for cerebral folate deficiency. 

Symptoms 

CFD usually begins in infancy or early childhood. Some children develop typically at first but then start to lose skills or show signs of slowing development. In other children, challenges appear early on.  Parents may notice:  

• Speech delay, motor delay, or loss of skills the child once had. 

• Language difficulties, repetitive behaviors, and challenges with social interaction. 

• Neurological symptoms like seizures, low muscle tone, poor balance or coordination, unusual movements, or stiffness. 

• Physical changes such as slower head growth or smaller head size. 

• Sensory differences such as vision or hearing changes. 

• Everyday challenges like irritability, sleep problems, or feeding difficulties in infancy. 

Because these symptoms overlap with autism and other developmental conditions, CFD is often overlooked without specific testing.    

Causes 

CFD can happen for a few different reasons:  

• Folate receptor autoantibodies (FRAAs). These are proteins made by the immune system that block folate from getting into the brain. 

• Genetic changes. Rare inherited conditions can affect the body’s ability to transport folate. 

• Energy or metabolic issues. The process of moving folate into the brain requires energy, so children with mitochondrial or metabolic conditions may have difficulty. 

• Secondary causes. Sometimes CFD appears alongside other medical conditions. 

 In children with autism, FRAAs are one of the most common causes of CFD.

Doctors use a combination of history, testing, and lab work to check for CFD. Common steps include: 

• Folate Receptor Antibody Test (FRAT): this blood test looks for autoantibodies that block folate from entering the brain. A positive test suggests that folate may not be transported properly and that treatment with leucovorin (folinic acid) may help. 

• Cerebrospinal fluid (CSF) testing: a lumbar puncture can measure folate levels in the fluid around the brain and spinal cord. Low CSF folate confirms the diagnosis. 

• Genetic testing: some children are checked for rare changes in the folate receptor gene (FOLR1). 

• Brain imaging: in some cases, MRI scans may show changes in brain development. 

• Other metabolic tests: doctors may check for mitochondrial or energy-related issues that can affect folate transport. 

A FRAT test is often a helpful first step since it’s a simple blood draw and can guide whether a trial of treatment may be useful. 

The main treatment for CFD is folinic acid (leucovorin), a special prescription form of folate that can get into the brain even when the usual pathway is blocked. 

• Leucovorin treatment is usually long-term and taken daily. 

• Starting leucovorin treatment early often leads to the best outcomes. 

• Families and doctors watch for improvements in speech, social interaction, learning, coordination, and behavior. 

• Some children also experience better seizure control with leucovorin treatment. 

• Regular follow-up is important so the care team can adjust the dose and monitor progress. 

Important note: regular folic acid supplements are not helpful for CFD and may interfere with leucovorin’s (folinic acid) effectiveness.