Abstract
Porcine Liver Decomposition Product (PLDP) was obtained by treating pig liver homogenate with protease and filling it into capsules. We have already confirmed from three clinical trials that PLDP enhances visual memory and delays memory recall, and we believe that its activity is due to various phospholipids, including phosphatidylcholine (PC). In this study, we clinically evaluated PLDP for depressive symptoms caused by a decline in cognitive function. This clinical trial was conducted using the Revised Hasegawa Dementia Scale (HDS-R). The HDS-R (maximum score is 30 points) is a test similar to the Mini-Mental State Examination (MMSE), which is commonly used in Japan. Dementia is suspected if the score falls below 20 on the HDS-R. Additionally, in a previous clinical trial, there was no change in scores in the placebo group after three doses of the HDS-R. In order to clearly confirm the effectiveness of PLDP, this study was conducted under stricter conditions (HDS-R points of 15 to 23) than previous clinical trials (all participants had scores of 20 or higher). Therefore, from ethical considerations, a clinical trial was conducted using the scores before PLDP administration as a control. In this study, PLDP was administered orally at 4 capsules per day, and the HDS-R was confirmed 2 and 4 weeks after administration. A significant increase in HDS-R scores was observed at 2 and 4 weeks after PLDP administration. Additionally, regarding each item of the HDS-R, PLDP significantly increased 2 and 4 weeks after oral administration for the question items assessing delayed recall, and the question item assessing verbal fluency tasks was recognized. From the above results, we confirmed the reproducibility of the effect of PLDP in improving the delayed recall of verbal memories. Furthermore, increasing scores on verbal fluency tasks suggest that PLDP may enhance frontal lobe function and prevent or improve depressive symptoms. The effects observed in this study may differ from the mechanisms of action of existing antidepressants, and we believe that this may lead to the discovery of new antidepressants.