Decline in sexual activity in ageing men: correlation with sex hormone levels and testicular changes

Abstract

The menopause clearly marks the end of the reproductive phase in the female, but no comparable event of sudden discontinuity in fertility occurs in the male. Successful paternity in man has been recorded at the age of 94 (Seymour, Duffy & Koerner, 1935). This difference between the sexes is rather surprising, as the male does not seem to age in a fundamentally different way from the female and as, moreover, the death rate for males is higher in all age groups, than for females. This may be related to the presence of only one X chromosome, the eventual defects of which cannot be compensated for by the activity of the homologue. The Y chromosome does not appear to bear vital genes, as it is not essential for life, XO individuals being perfectly viable, in distinction to the YO genotype. Moreover in the absence of male inducers, the phenotype is female, suggesting that the male phenotype is a more complex differentiation. For whatever reason, the lower viability of the male remains a striking fact: males represent only 35% of the age group over 75 years. The persistence of reproductive function into old age is therefore the more surprising. This does not mean, however, that a gradual decrease in sexual activity and testicular function in the ageing male does not occur. From adolescence onwards, there is a continuous decline in sexual interest, arousal and activity, without a sudden discontinuity in any age group.If the frequency of orgasm is taken as a parameter (Fig. 1) it is found that at age 50 frequency has fallen to about 50% of what it was at age 30, and it approaches zero by age 75 (Bishop, 1970). It is remarkable that the slope of this curve does not show any abrupt change. An even more dramatic decline with age may be observed in the capacity for repeated orgasm. This reaches its peak in preadolescence, declining very rapidly after 20 years of age and in elderly males recovery may require 24 hr or even more (Harman, 1978). The quality of sexual activity also decreases with age: sexual arousal is slower and requires more intense stimuli, ejaculations are less forceful, detumescence after orgasm is quicker and the vasocongestive increase in testicular size during sexual excitement is decreased, as is the psychosexual pleasure. Frequency of erectal impotence increases exponentially with age: at 40, 50, 60 and 75 years respectively, about 2, 7, 28 and 50% of males are affected. A. Vermeulen3-5 r 3-0 2-5 I 2-0 1-5 1-0 0-5 Corrected meon Age groups (yeors) -70 -75 -80 -85

Hormonal Changes and Sexual Function in Aging Men*

“…Second, in common with several previous investigations (8)(9)(10), we found a decreased circulating level of T, an increase in SBP, and a consequently greater decrease in calculated free than in total T accompanied by large increases in plasma LH and FSH but no age-related change in estradiol or PRL. Although only 1 blood sample was taken from each subject, and circulating T levels do fluctuate, the incidence of large fluctuations is apparently not sufficient to invalidate 1-sample studies in relatively large populations due to randomization of error (8)(9)(10).…”

“…Although only 1 blood sample was taken from each subject, and circulating T levels do fluctuate, the incidence of large fluctuations is apparently not sufficient to invalidate 1-sample studies in relatively large populations due to randomization of error (8)(9)(10). In a separate study of 30 eugonadal patients in our laboratory, 2 blood samples taken several months apart were highly correlated in T level (r = 0.75).…”

“…A variety of studies has also reported that circulating levels of testosterone (T) fall progressively with advancing age (8)(9)(10). Since T plays an important role in the regulation of sexual behavior in men and males of other species (11,12), it has often been hypothesized, but never demonstrated, that androgen deficiency is responsible for declining sexual function in the aging male (10,13).…”

“…A variety of studies has also reported that circulating levels of testosterone (T) fall progressively with advancing age (8)(9)(10). Since T plays an important role in the regulation of sexual behavior in men and males of other species (11,12), it has often been hypothesized, but never demonstrated, that androgen deficiency is responsible for declining sexual function in the aging male (10,13). On the other hand, since variations in T levels within the accepted normal range do not appear to have any major influence on sexual behavior in young adult humans (14) or rats (15), the age-related decreases in T might not be sufficient to result in significant sexual dysfunction.…”

Rheumatoid arthritis, the contraceptive pill, and androgens.

“…In men the mean concentration declines roughly linearly from about the age of 30 onwards, and the decline is about fivefold between the ages of 30-39 and 80 and older. 27 In women, in contrast, mean free testosterone concentrations reportedly decline between 30 and 50 but apparently rise thereafter. 28 Schiff has reported a relative androgen excess in postmenopausal women contrasted with women before the menopause.29 Thus if RA were partially dependent on free testosterone concentrations then the sex ratios of patients by age at onset might be explained by these differing regression patterns.…”