This is a Japanese language peer-reviewed journal. Here is the study abstract, translated into English for your convenience.

Authors: Kinoshita T, Maruyama K, Tanigawa T.

Summary: We evaluated changes in Quality of Life (QOL) after treatment with Ubiquinol, the reduced form of coenzyme Q10 (Kaneka QH™) 100 mg for 6 months in 11 healthy elderly subjects residing in a care home, with the use of the SF-36 questionnaire. The results showed significant increases in the ‘vitality’ and ‘mental health’ scores; treatment with the reduced form of coenzyme Q10 related to improved QOL.

Plasma concentrations of the reduced form of coenzyme Q10 increased by approximately 4-fold after taking the test product, and the ratio of the reduced form of coenzyme Q10 to the total CoQ10 also tended to increase although the elevation was not significant.

The ‘vitality’ and ‘mental health’ correlated with the ratio of the reduced form of coenzyme Q10, whereas there was no correlation with the concentrations of the reduced form of coenzyme Q10. The findings have suggested that maintaining coenzyme Q10 in a highly reduced state is important for QOL improvement.