Cross-sectional studies have found a positive association between serum testosterone and some measures of cognitive ability in men (Barrett-Connor, Goodman-Gruen et al 1999; Yaffe et al 2002). Longitudinal studies have found that free testosterone levels correlate positively with future cognitive abilities and reduced rate of cognitive decline (Moffat et al 2002) and that, compared with controls, testosterone levels are reduced in men with Alzheimer’s disease at least 10 years prior to diagnosis (Moffat et al 2004). Studies of the effects of induced androgen deficiency in patients with prostate cancer have shown that profoundly lowering testosterone leads to worsening cognitive functions (Almeida et al 2004; Salminen et al 2004) and increased levels of serum amyloid (Gandy et al 2001; Almeida et al 2004), which is central to the pathogenesis of Alzheimer’s disease (Parihar and Hemnani 2004). Furthermore, testosterone reduces amyloid-induced hippocampal neurotoxity in vitro (Pike 2001) as well as exhibiting other neuroprotective effects (Pouliot et al 1996). The epidemiological and experimental data propose a potential role of testosterone in protecting cognitive function and preventing Alzheimer’s disease.
The researchers found that the dose of testosterone required to produce different effects in the body varied widely. The influence of testosterone and estradiol also differed. As the testosterone gel dose was reduced, the scientists showed, reductions in lean mass, muscle size, and leg-press strength resulted from decreases in testosterone itself. In contrast, increases in body fat were due to the related declines in estradiol. Both testosterone and estradiol levels were associated with libido and erectile function.
Both men and women with Alzheimer’s Disease were found to have an increased concentration of SHBG and decreased free androgen index when compared with controls (Paoletti et al 2004). In a prospective study of 574 men whose baseline age span was 32–87 years and who were followed for a mean of 19.1 years (range, 4–37), the risk of developing Alzheimers’ Disease decreased 26 percent for each 10 unit increase in free testosterone index. The authors concluded that testosterone may be important for the prevention and treatment of AD (Moffat et al 2004).
Your first step should be to see your doctor. If you think you have low testosterone, we cannot stress enough that you should proceed with caution and talk to a medical professional — taking a booster can definitely do more harm than good. Low testosterone can be a symptom of more serious problems, like a pituitary disorder or a side-effect of medication, and a booster can mask the root cause. A doctor will be able to evaluate your testosterone levels with a simple blood test, and if you both decide a booster is the way to go, give the ingredients of any supplement a once-over to make sure that they’re not at risk of making your personal health situation worse.
The testicles produce an enzyme called 11ßHSD-1 which protects your testosterone molecules from the effects cortisol. During times of prolonged stress and chronically elevated cortisol, there simply is too much cortisol for 11ßHSD-1 to handle. This results in testosterone molecules being destroyed inside the gonads before they even enter the bloodstream (8, 9).
The reliable measurement of serum free testosterone requires equilibrium dialysis. This is not appropriate for clinical use as it is very time consuming and therefore expensive. The amount of bioavailable testosterone can be measured as a percentage of the total testosterone after precipitation of the SHBG bound fraction using ammonium sulphate. The bioavailable testosterone is then calculated from the total testosterone level. This method has an excellent correlation with free testosterone (Tremblay and Dube 1974) but is not widely available for clinical use. In most clinical situations the available tests are total testosterone and SHBG which are both easily and reliably measured. Total testosterone is appropriate for the diagnosis of overt male hypogonadism where testosterone levels are very low and also in excluding hypogonadism in patients with normal/high-normal testosterone levels. With increasing age, a greater number of men have total testosterone levels just below the normal range or in the low-normal range. In these patients total testosterone can be an unreliable indicator of hypogonadal status. There are a number of formulae that calculate an estimated bioavailable or free testosterone level using the SHBG and total testosterone levels. Some of these have been shown to correlate well with laboratory measures and there is evidence that they more reliably indicate hypogonadism than total testosterone in cases of borderline biochemical hypogonadism (Vermeulen et al 1971; Morris et al 2004). It is important that such tests are validated for use in patient populations relevant to the patient under consideration.
Fatherhood decreases testosterone levels in men, suggesting that the emotions and behavior tied to decreased testosterone promote paternal care. In humans and other species that utilize allomaternal care, paternal investment in offspring is beneficial to said offspring's survival because it allows the parental dyad to raise multiple children simultaneously. This increases the reproductive fitness of the parents, because their offspring are more likely to survive and reproduce. Paternal care increases offspring survival due to increased access to higher quality food and reduced physical and immunological threats. This is particularly beneficial for humans since offspring are dependent on parents for extended periods of time and mothers have relatively short inter-birth intervals. While extent of paternal care varies between cultures, higher investment in direct child care has been seen to be correlated with lower average testosterone levels as well as temporary fluctuations. For instance, fluctuation in testosterone levels when a child is in distress has been found to be indicative of fathering styles. If a father's testosterone levels decrease in response to hearing their baby cry, it is an indication of empathizing with the baby. This is associated with increased nurturing behavior and better outcomes for the infant.
Individuals with metabolic syndrome are at increased risk for developing coronary artery disease and diabetes mellitus. Predicting who might develop the metabolic syndrome would allow preventive measures to be taken in addition to weight control and other lifestyle modifications such as cessation of smoking and increased exercise. It is known that with decreasing testosterone availability in aging males there is an increase in fat mass and decrease in lean body mass (van den Beld et al 2000), there are disorders of insulin and glucose metabolism (Haffner et al 1996) and dyslipidemia (Tsai et al 2004). Kupelian and colleagues (2006) in analyzing data from the Massachusetts Male Aging Study demonstrated that men with low levels of testosterone, sex hormone-binding globulin, or clinical androgen deficiency, especially men with a BMI of greater than 25, were at increased risk of developing the metabolic syndrome and hence, diabetes mellitus and/or coronary artery disease.
Androgens may modulate the physiology of vaginal tissue and contribute to female genital sexual arousal. Women's level of testosterone is higher when measured pre-intercourse vs pre-cuddling, as well as post-intercourse vs post-cuddling. There is a time lag effect when testosterone is administered, on genital arousal in women. In addition, a continuous increase in vaginal sexual arousal may result in higher genital sensations and sexual appetitive behaviors.
The reasons for considering such therapy become evident from the many associations, indicated above, that reduced testosterone has with a variety of both physiological functions (bone metabolism, muscle mass, cognitive function, libido, erectile function) and pathophysiological states (metabolic syndrome, diabetes mellitus, obesity, insulin resistance, autoimmune disease). Although a definitive long-term, large scale placebo-controlled double-blind study of testosterone therapy in the aging male has not yet been carried out, multiple shorter-term trials have suggested improvement by testosterone with a resultant enhancement of muscle mass, bone density, libido, erectile function, mood, motivation and general sense of well-being.
Other Potential risks that can be caused by use of testosterone supplements are: People who take good testosterone supplements or any other kind of testosterone boosters can also experience many other side effects, including stomachache, problems with urination, dizziness, mood changes, intermittent breathing during sleep, changes in testicles, appetite loss, inflammation of gums, weight gain, nausea, painful erection, and protracted erection.
For men with low blood testosterone levels, the benefits of hormone replacement therapy usually outweigh potential risks. However, for most other men it's a shared decision with your doctor. It offers men who feel lousy a chance to feel better, but that quick fix could distract attention from unknown long-term hazards. "I can't tell you for certain that this raises your personal risk of heart problems and prostate cancer, or that it doesn't," Dr. Pallais says.