[Analyses of factors contributing to the erectile dysfunction with aging by nocturnal penile tumescence, penile blood pressure index and papaverine test].

To evaluate the factors contributing to the decline in erectile function with age, we performed measurement of nocturnal penile tumescence (NPT) and penile vascular examinations in 407 men. The following results were obtained. 1) The penile circumferential increment during NPT measured by an erectometer was gradually decreased with age, especially markedly after 60 years of age. The percentage of subjects in whom the NPT was less than 10 mm increased with age: 2.7% in the 5th decade, 7.1% in the 6th decade, 16.7% in the 7th decade and 29.1% in the 8th decade. These findings indicate that the incidence of organic erectile dysfunction increased with age. 2) To evaluate the penile vascular status, measurement of penile blood pressure index (PBPI) and papaverine test were performed. The mean PBPI values were significantly decreased in the subjects over 70 years of age. The percentage of subjects having good response to papaverine injection obviously decreased with age: 66.7% between 50 to 59 years, 48.6% between 60 to 69 years, and 15.8% of over 70 years. All subjects in whom the NPT was less than 10 mm showed either a low PBPI level of less than 0.6 or an incomplete response to papaverine injection. These results suggest that penile vascular impairment plays a major role in the age-associated decline in erectile function. 3) We investigated the relationship between cigarette smoking and penile vascular impairment. Smokers showed not only lower PBPI values but higher incidence of the incomplete response to papaverine injection than nonsmokers. Therefore, it is considered that cigarette smoking is a significant risk factor in the erectile dysfunction that occurred in the aged.