The QUALITY of spermatozoa decreases with age

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When assessing the development of male fertility over time, it is necessary to consider two main aspects: the direct effects of ageing on the body and the indirect effects related to lifestyle. Physiological changes due to ageing have been described in the testicles, seminal vesicles, prostate and epididymis. At the testicular level, there is a decrease and reduction in the function of Leydig cells (the site of production of androgenic steroid hormones), a degeneration of sperm precursor cells with a consequent reduction in spermatogenesis, and a reduction in the number of Sertoli cells (testicular cells with support functions for germ cells)¹. In men, the decrease in testosterone production by the testicles leads to an overall decrease in circulating levels of sex hormones and this decline begins from the age of thirty. With increasing age, moreover, there is an increase in oxidative stress in the cells resulting in an accumulation of reactive oxygen species (ROS) that are responsible for damaging the DNA contained in the spermatozoa.²favouring chromosomal instability³. Chromosomal instability and the resulting fragmentation of sperm DNA correlate with an increased risk of genetic alterations in the product of conception predisposing to miscarriage. Age also directly affects sperm motility. Studies have shown that sperm motility appears to decrease by 0.8% for each year of age. At prostate level, smooth muscle atrophy occurs and the amount of protein and water in the seminal fluid decreases, resulting in a reduction in sperm volume and sperm motility. Increasing age also implies the possible development of overweight, chronic diseases, urogenital infections, and predisposes to long-term exposure to toxic substances that may impact fertility.⁴. Being overweight and obese can lead to the development of metabolic syndrome, a picture characterised by hypercholesterolaemia, hypertension, type 2 diabetes, hypertriglyceridaemia, all conditions that negatively affect men's health in general, but also reproductive health. It is estimated that the risk of male infertility increases by 10% for every 9 kg of excess weight⁵. Increased fat mass, in fact, often associated with insulin resistance, correlates with hormonal dysfunctions that affect the normal functioning of the hypothalamus-pituitary-testicle axis. Type 2 diabetes also results in decreased sperm viability and increased DNA fragmentation. A retrospective study of 3,698 infertile men showed an accessory gland infection rate of 6.1% in patients 40 years old, with a significantly lower total sperm count in patients with an infectious process⁶. In addition, chronic exposure to cigarette smoke generates oxidative stress resulting in damage to sperm cell membranes, mitochondrial alterations and fragmentation of sperm DNA. 

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