Effect of kihito extract granules on cognitive function in patients with Alzheimer's‐type dementia

Background: It has been recently suggested that Japanese herbal (kampo) medicines, such as kami‐untan‐to, may improve cognitive function in elderly subjects with Alzheimer's disease. Polygalae radix is thought to be a useful component of kami‐untan‐to because it enhances the activity of choline acetyltransferase in cultured neuronal cells. The purpose of the present study was to investigate the safety and usefulness of kihito extract granules, a commercially available Japanese herbal medicine that contains P. radix , for elderly patients with senile dementia. Methods: Seventy‐five elderly subjects (84.4 ± 6.4 years) with senile dementia of Alzheimer type according to Diagnostic and Statistical Manual of Mental Disorders , 4th edition criteria were randomly assigned to the non‐treatment, goshajinkigan (control kampo medicine) or kihito groups. Each medicine was given three times a day for 3 months. Results: There was no severe adverse event in any of the groups. We examined the Mini‐Mental State Examination (MMSE), the activities of daily living (ADL) scale and cerebrovascular single photon emission computed tomography (SPECT) before and after treatment. MMSE scores were significantly improved only in the kihito group (+1.65 ± 0.53) but not in the non‐treatment (−0.3 ± 0.67) and goshajinkigan (−0.58 ± 0.49) groups. ADL scores remained unchanged in all groups. Treatment with kihito was not associated with an increase in cerebral blood flow. Conclusion: These results propose that kihito may be useful and has potential to be tested as a medicine for Alzheimer's‐type senile dementia, although further examination is required to clarify the mechanism of the improving effect of kihito on cognitive function.