Folic acid (
folate) levels were measured in the serum of patients with various neurological diseases in Japan. Thirty-six patients showed decreased serum
folate levels among 343 consecutive neurological patients (10.5%).
Folate administration (15 mg/d) to
folate-deficient patients improved neurological symptoms in 24 of 36 cases (67%). Serum
folate levels were significantly lower in female than in male
folate-deficient patients.
Folate-deficient patients showed predominantly axonal neuropathy, which responded to
folate supplementation more markedly. Male patients more frequently exhibited neuropathy, especially demyelinating and motor-dominant neuropathy, than females.
Anemia was correlated with male sex and low serum
folate levels. Male patients were more responsive than females to
folate treatment. More male patients had taken excess alcohol or received
gastrectomies than females. Neurological symptoms were more frequently improved by
folate supplementation in patients with neuropathy than exclusive
encephalopathy. Serum
folate levels were lower in patients with
encephalopathy, especially those with
dementia, while
folate therapy was more effective in neurological patients without
dementia.
Dysgeusia and
anemia improved in all patients after
folate administration. Neurological patients with malabsorption or treated with continuous
drip infusion were resistant to
folate therapy. Since
folate-responsive neuroencepahlopathies are not rare among patients with neurological diseases in Japan, the serum
folate level would serve as a valuable
indicator for
folate supplement
therapy.