Attention, memory, and spatial ability are key cognitive functions affected by testosterone in humans. Preliminary evidence suggests that low testosterone levels may be a risk factor for cognitive decline and possibly for dementia of the Alzheimer's type,[100][101][102][103] a key argument in life extension medicine for the use of testosterone in anti-aging therapies. Much of the literature, however, suggests a curvilinear or even quadratic relationship between spatial performance and circulating testosterone,[104] where both hypo- and hypersecretion (deficient- and excessive-secretion) of circulating androgens have negative effects on cognition.
Testosterone is significantly correlated with aggression and competitive behaviour and is directly facilitated by the latter. There are two theories on the role of testosterone in aggression and competition.[77] The first one is the challenge hypothesis which states that testosterone would increase during puberty thus facilitating reproductive and competitive behaviour which would include aggression.[77] Thus it is the challenge of competition among males of the species that facilitates aggression and violence.[77] Studies conducted have found direct correlation between testosterone and dominance especially among the most violent criminals in prison who had the highest testosterone levels.[77] The same research also found fathers (those outside competitive environments) had the lowest testosterone levels compared to other males.[77]
Several treatments were promoted in the pre-PGE1, pre-prostaglandin era, including yohimbine, trazodone, testosterone, and various herbal remedies. None of these is currently recommended under the updated American Urological Association Guidelines for the Treatment of Erectile Dysfunction.15 Testosterone supplementation is only recommended for men with low testosterone levels.
But if a man with sleep apnea is diagnosed with low testosterone alone, taking the supplemental hormone can worsen sleep apnea. That's why it's crucial for men with low testosterone to get a thorough workup by an endocrinologist so underlying conditions that can cause low testosterone, such as sleep apnea or pituitary-gland tumors, don't go undiagnosed, Dr. Goodman says.
Barbara Mintzes, at the University of British Columbia, said in a Skype interview, "Androgel was approved for a real condition—men who have a number of clinical or acquired conditions that affect testosterone, either through the testes or pituitary gland. So testosterone replacement therapy makes sense, and producing it in a gel makes sense. Where there is an actual need for the product, there's nothing wrong with that." But, she added, "When this gets marketed for what is essentially healthy aging, the antennas go up."

The mechanism of age related decreases in serum testosterone levels has also been the subject of investigation. Metabolic clearance declines with age but this effect is less pronounced than a reduction in testosterone production, so the overall effect is to reduce serum testosterone levels. Gonadotrophin levels rise during aging (Feldman et al 2002) and testicular secretory responses to recombinant human chorionic gonadotrophin (hCG) are reduced (Mulligan et al 1999, 2001). This implies that the reduced production may be caused by primary testicular failure but in fact these changes are not adequate to fully explain the fall in testosterone levels. There are changes in the lutenising hormone (LH) production which consist of decreased LH pulse frequency and amplitude, (Veldhuis et al 1992; Pincus et al 1997) although pituitary production of LH in response to pharmacological stimulation with exogenous GnRH analogues is preserved (Mulligan et al 1999). It therefore seems likely that there are changes in endogenous production of GnRH which underlie the changes in LH secretion and have a role in the age related decline in testosterone. Thus the decreases in testosterone levels with aging seem to reflect changes at all levels of the hypothalamic-pituitary-testicular axis. With advancing age there is also a reduction in androgen receptor concentration in some target tissues and this may contribute to the clinical syndrome of LOH (Ono et al 1988; Gallon et al 1989).

Replacement therapy may produce desired results, such as greater muscle mass and a stronger sex drive. However, the treatment does carry some side effects. Oily skin and fluid retention are common. The testicles may also shrink, and sperm production could decrease significantly. Some studies have found no greater risk of prostate cancer with testosterone replacement therapy, but it continues to be a topic of ongoing research.
Stanley A Brosman, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, American Association for the Advancement of Science, American Association for Cancer Research, American College of Surgeons, American Medical Association, American Urological Association, Society for Basic Urologic Research, Society of Surgical Oncology, Society of Urologic Oncology, Western Section of the American Urological Association, Association of Clinical Research Professionals, American Society of Clinical Oncology, International Society of Urology, International Society of Urological Pathology
Abnormally high levels of testosterone could be the result of an adrenal gland disorder, or even cancer of the testes. High levels may also occur in less serious conditions. Congenital adrenal hyperplasia, which can affect males and females, is a rare but natural cause for elevated testosterone production. Your doctor may order other tests if your levels are exceedingly high.
Acupuncture may help treat psychological ED, though studies are limited and inconclusive. You’ll likely need several appointments before you begin to notice any improvements. When choosing an acupuncturist, look for a certified practitioner who uses disposable needles and follows U.S. Food and Drug Administration guidelines for needle disposal and sterilization.

It doesn’t get more natural than getting a good night’s sleep. Research published in the Journal of the American Medical Association showed that lack of sleep can greatly reduce a healthy young man’s testosterone levels. That effect is clear after only one week of reduced sleep. Testosterone levels were particularly low between 2 and 10 p.m. on sleep-restricted days. Study participants also reported a decreased sense of wellbeing as their blood testosterone levels dropped.
TT may help you but it may have adverse (harmful) results. (See discussion of these side effects below.) The Federal Drug Administration (FDA) has said that testosterone drug labels should state that there is a risk for heart disease and stroke for some men using testosterone products. All men should be checked for heart disease and stroke before, and periodically while on, TT. The AUA however, on careful review of evidence-based peer review literature, has stated that there is no strong evidence that TT either increases or decreases the risk of cardiovascular events.
Several pathways have been described to explain how information travels from the hypothalamus to the sacral autonomic centers. One pathway travels from the dorsomedial hypothalamus through the dorsal and central gray matter, descends to the locus ceruleus, and projects ventrally in the mesencephalic reticular formation. Input from the brain is conveyed through the dorsal spinal columns to the thoracolumbar and sacral autonomic nuclei.

A number of epidemiological studies have found that bone mineral density in the aging male population is positively associated with endogenous androgen levels (Murphy et al 1993; Ongphiphadhanakul et al 1995; Rucker et al 2004). Testosterone levels in young men have been shown to correlate with bone size, indicating a role in determination of peak bone mass and protection from future osteoporosis (Lorentzon et al 2005). Male hypogonadism has been shown to be a risk factor for hip fracture (Jackson et al 1992) and a recent study showed a high prevalence of hypogonadism in a group of male patients with average age 75 years presenting with minimal trauma fractures compared to stroke victims who acted as controls (Leifke et al 2005). Estrogen is a well known determinant of bone density in women and some investigators have found serum estrogen to be a strong determinant of male bone density (Khosla et al 1998; Khosla et al 2001). Serum estrogen was also found to correlate better than testosterone with peak bone mass (Khosla et al 2001) but this is in contradiction of a more recent study showing a negative correlation of estrogen with peak bone size (Lorentzon et al 2005). Men with aromatase deficiency (Carani et al 1997) or defunctioning estrogen receptor mutations (Smith et al 1994) have been found to have abnormally low bone density despite normal or high testosterone levels which further emphasizes the important influence of estrogen on male bone density.

It doesn’t get more natural than getting a good night’s sleep. Research published in the Journal of the American Medical Association showed that lack of sleep can greatly reduce a healthy young man’s testosterone levels. That effect is clear after only one week of reduced sleep. Testosterone levels were particularly low between 2 and 10 p.m. on sleep-restricted days. Study participants also reported a decreased sense of wellbeing as their blood testosterone levels dropped.
The other interesting thing about the study: men’s testosterone levels were lowest in March (at the end of winter) and highest in August (at the end of summer). Sunlight affects your vitamin D production, so you have seasonal dips and peaks. Get a blood test to check your levels, and if you’re low, take a high-quality vitamin D3 supplement. If you’re going to take D3, take vitamin K2 and vitamin A with it. The three work in sync, so you want them all to be balanced. Here are my dosage recommendations.
Patients at high cardiovascular risk should not be treated for ED until their cardiac condition is stabilize. These conditions include unstable or refractory angina, myocardial infarction or cerebrovascular accident within the past 2 weeks, uncontrolled hypertension, New York Heart Association (NYHA) Functional Classification III-IV congestive heart failure, high-risk arrhythmias, hypertrophic obstructive cardiomyopathies, and moderate-to-severe valvular disease.25 This class of drugs is also contraindicated in patients who use nitroglycerin or nitrate-containing compounds.26, 27
The device consists of an acrylic cylinder placed over the penis that uses a lubricant to achieve a good seal between the penile body and cylinder. An erection is then achieved by creating a vacuum inside the cylinder with a pump connected to the cylinder. Once an erection is achieved, a constriction band is applied to the base of the penis to maintain the erection. The cylinder can then be removed and the patient can engage in intercourse with the constriction band at the base of the penis maintaining the erection. The band can remain on for approximately 30 minutes and then must be removed. The erection produced by the device differs from a normal erection likely because of venous occlusion from the constriction band resulting in generalized swelling of the entire penis, with probable preservation of arterial inflow.

^ Southren AL, Gordon GG, Tochimoto S, Pinzon G, Lane DR, Stypulkowski W (May 1967). "Mean plasma concentration, metabolic clearance and basal plasma production rates of testosterone in normal young men and women using a constant infusion procedure: effect of time of day and plasma concentration on the metabolic clearance rate of testosterone". The Journal of Clinical Endocrinology and Metabolism. 27 (5): 686–94. doi:10.1210/jcem-27-5-686. PMID 6025472.


All devices that are currently approved by the FDA are considered safe for use in magnetic resonance imaging environments. However, 2 previously approved devices–the OmniPhase and the DuraPhase penile prostheses–are not considered safe in this environment. Other surgical procedures–including venous ligation to limit penile venous outflow and penile revascularization procedures–are rarely successful and are not recommended.19 These surgeries are only indicated when a patient demonstrates recent-onset ED and an occlusive lesion seen on angiogram or magnetic resonance angiography and should be performed only in centers of excellence for ED. 

A team led by Dr. Joel Finkelstein at Massachusetts General Hospital investigated testosterone and estradiol levels in 400 healthy men, 20 to 50 years of age. To control hormone levels, the researchers first gave the participants injections of a drug that suppressed their normal testosterone and estradiol production. The men were randomly assigned to 5 groups that received different amounts (from 0 to 10 grams) of a topical 1% testosterone gel daily for 16 weeks. Half of the participants were also given a drug to block testosterone from being converted to estradiol.
The use of anabolic steroids (manufactured androgenic hormones) shuts down the release of luteinising hormone and follicle stimulating hormone secretion from the pituitary gland, which in turn decreases the amount of testosterone and sperm produced within the testes. In men, prolonged exposure to anabolic steroids results in infertility, a decreased sex drive, shrinking of the testes and breast development. Liver damage may result from its prolonged attempts to detoxify the anabolic steroids. Behavioural changes (such as increased irritability) may also be observed. Undesirable reactions also occur in women who take anabolic steroids regularly, as a high concentration of testosterone, either natural or manufactured, can cause masculinisation (virilisation) of women.
Findings that improvements in serum glucose, serum insulin, insulin resistance or glycemic control, in men treated with testosterone are accompanied by reduced measures of central obesity, are in line with other studies showing a specific effect of testosterone in reducing central or visceral obesity (Rebuffe-Scrive et al 1991; Marin, Holmang et al 1992). Furthermore, studies that have shown neutral effects of testosterone on glucose metabolism have not measured (Corrales et al 2004), or shown neutral effects (Lee et al 2005) (Tripathy et al 1998; Bhasin et al 2005) on central obesity. Given the known association of visceral obesity with insulin resistance, it is possible that testosterone treatment of hypogonadal men acts to improve insulin resistance and diabetes through an effect in reducing central obesity. This effect can be explained by the action of testosterone in inhibiting lipoprotein lipase and thereby reducing triglyceride uptake into adipocytes (Sorva et al 1988), an action which seems to occur preferentially in visceral fat (Marin et al 1995; Marin et al 1996). Visceral fat is thought to be more responsive to hormonal changes due to a greater concentration of androgen receptors and increased vascularity compared with subcutaneous fat (Bjorntorp 1996). Further explanation of the links between hypogonadism and obesity is offered by the hypogonadal-obesity-adipocytokine cycle hypothesis (see Figure 1). In this model, increases in body fat lead to increases in aromatase levels, in addition to insulin resistance, adverse lipid profiles and increased leptin levels. Increased action of aromatase in metabolizing testosterone to estrogen, reduces testosterone levels which induces further accumulation of visceral fat. Higher leptin levels and possibly other factors, act at the pituitary to suppress gonadotrophin release and exacerbate hypogonadism (Cohen 1999; Kapoor et al 2005). Leptin has also been shown to reduce testosterone secretion from rodent testes in vitro (Tena-Sempere et al 1999). A full review of the relationship between testosterone, insulin resistance and diabetes can be found elsewhere (Kapoor et al 2005; Jones 2007).
Dr. Fugh-Berman said these campaigns encourage men to "ask your doctor" whether their weight gain, falling asleep after dinner, reduced energy, and diminished sex drive are due to "Low T." At the same time, the companies are working other angles to influence doctors' prescribing practices through industry-sponsored continuing medical education (CME) courses and sponsored medical journal articles. They have even created a respectable-sounding journal called The Aging Male. Fugh-Berman said all these channels "are being used to persuade doctors they should be treating this."
It also had a purpose. It turns out posing in powerful stances causes your testosterone to increase within 20 minutes [13,14]. In those two studies, power posing for just a few minutes also dropped cortisol and boosted confidence. It’s a great way to start your day, or to give yourself an edge before a job interview or a big presentation. They don’t call it “warrior pose” for nothing!
However, testosterone is only one of many factors that aid in adequate erections. Research is inconclusive regarding the role of testosterone replacement in the treatment of erectile dysfunction. In a review of studies that looked at the benefit of testosterone in men with erection difficulties, nearly half showed no improvement with testosterone treatment. Many times, other health problems play a role in erectile difficulties. These can include: 
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