If patients with Kearns-Sayre syndrome commonly are deficient in folate, logic would presume folinic acid therapy may benefit their symptoms. A team from Spain tested this theory in the article “Follow-up of Folinic Acid Supplementation for Patients with Cerebral Folate Deficiency and Kearns-Sayre Syndrome,” which was published in Orphanet Journal of Rare Diseases. Although the team found the majority of treated patients saw no improvement, one patient who was treated early in disease onset had improved neurological and radiological tests.

“Early treatment with high-dose folinic acid therapy seems to be advisable for the treatment of Kearns-Sayre syndrome,” wrote the authors. The patient who showed great improvements was one of eight participants recruited for the study. Two patients refused treatment, and the other six were treated at two hospitals in Spain. Each patient received an oral dose of 1 to 3 mg/kg folinic acid each day for one to eight years, depending on the patient.

The research team used several methods to detect effects of folinic acid treatment. At the beginning of the study, they conducted magnetic resonance imaging and computed tomography scans to obtain neurological data and collected cerebrospinal fluid samples to detect levels of 5-methyltetrahydrofolate (the dietary form of folate that is detectable in circulation). Following treatment, patients were retested by the same methods.

At the beginning of the study, all patients were deficient in 5-methyltetrahydrofolate. Those patients who were retested at the end of the study saw a recovery of 5-methyltetrahydrofolate. Yet despite a return to normal levels, four patients had disease progression detectable by neuroimaging, and five had disease progression determined through neurological tests. Brain atrophy affected a large portion of the brain. Of the two patients who showed neurological improvements, one showed signs of improved white matter in the brain. This patient was treated early and was treated with increasing doses of folinic acid.

Previous studies have begun to elucidate the reasons why folic acid deficiency may contribute to Kearns-Sayre syndrome. “Disorders of Folate Metabolism the the Kearns-Sayre Syndrome,” published in Revue Nerologique, suggested that the deficiency affects metabolism in the brain. Everything from DNA synthesis to hormone production can be affected by folic acid deficieny, implying that folic acid is crucial to brain function. Supplying supplemental folinic acid early in brain development in patients with Kearns-Sayre syndrome may slow disease progression.