"A retrospective analysis by researchers at Beth Israel Deaconess Medical Center (BIDMC) published in The New England Journal of Medicine found no causal relationship between testosterone replacement and prostate cancer or heart disease risk
"We reviewed decades of research and found no compelling evidence that testosterone replacement therapy increases the incidence of prostate cancer or cardiovascular disease," said Abraham Morgentaler, a urologist at BIDMC and associate clinical professor at Harvard Medical School. "Although it would be helpful to have data from long-term, large-scale studies, it must also be recognized that there already exists a substantial body of research on the effects of testosterone in men."
"The men with lower testosterone levels had an increased risk of dying from any cause, but most particularly of cardiovascular disease," Khaw tells WebMD. "We looked at cancer, too, and found no evidence of a link to cancer with higher testosterone levels."
Nearly 12,000 men enrolled in the long-term study from 1993 to 1997. More than 800 of the men died by 2003; Khaw compared these men's testosterone levels to those of some 1,500 living study participants.
After adjusting for factors that might affect risk of death -- including age, weight, smoking, alcohol use, high blood pressure, diabetes, physical activity, education, and social class -- the link between low testosterone and earlier death remained.
Compared to men with the lowest quartile (25%) of testosterone levels:
Men in the second lowest quartile were 25% less likely to die. Men in the second highest quartile were 38% less likely to die. Men in the highest quartile were 41% less likely to die."
I wish I still had the link to the study that discusses the lowered incidence of Alzheimers' and higher Testosterone levels in older men.
The gist was that higher Testosterone levels in older men (60+)had a lower rate of developing the "plaque" that causes the loss of brain function known as Alzheimers. Just think, a better QOL, a stronger heart, more flexible (and less potentially plugged) arteries, better brain funtion, and oh yeah, sexual function w/o the little blue pill too!
I'm glad i'm on TRT now, so I have the potential to age gracefully and stay as strong as possible in every way as I age.
I remember life before TRT, and life was barely an existence, where now even though I have some physical issues, I still have the desires of a 17 year old and the ability to carry it out, where before I just wasn't interested...
I had three issues that TRT fixed. All of these problems had Dr's scratching their heads for years. 1. My heart used to lose rhythm for several seconds when doing cardio. After two months of TRT it's fixed. (Dr's told me not to worry about it over the years. Yeah....)
I used to have lower ab muscle spasms that would last for weeks at a time. Now they're history.
My joints used to hurt. Now no joint pain. I think I was slowly falling apart and now my body feels fresh. We all know that Dr's never want to fix the root of the problem though. They would rather hand out a pile of pills to treat symptoms.
Testosterone levels are a fixed parameter over 4 years? I do not think so. A number of men will shift from one cohort to another over a period of time
Testosterone levels are not only predictive but causative. (For example, perhaps T levels reflect a different cause, a cause which also predicts for mortality. Khaw does include many factors of interest--see the Conclusions section--but epidemiology never answers every such quibble.)
It may be that another predictor of mortality is a more powerful predictor and Prof. Khaw did not measure it, or power his study for it. (E.g., it is occult disease itself which lowers T.)
There were few deaths over a short time--4 years only--so the apparent reduction of mortality is exaggerated. I cannot tell if it even statistically significant (because of the particular methodology).
Correlation is not causation. This study in no way "proves" that T supplementation would change the outcome for men and mortality. This happens to be a study designed and powered for cardiovascular mortality. I do not know from this study that giving T to men at risk will be helpful.
[i]Androgens in the etiology of Alzheimer's disease in aging men and possible therapeutic interventions.
Fuller SJ, Tan RS, Martins RN. Centre of Excellence for Alzheimer's Disease Research and Care, School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia.
Animal experiments and cell biology studies have provided evidence that both estrogens and androgens can play a protective role against Alzheimer's disease (AD) related neurodegeneration. Males who become hypogonadal in later life often report problems with their memory.
Lower than normal testosterone levels have also been detected in patients prior to the onset of AD, as well as in younger late-onset male AD patients, when compared to appropriate controls. The results of some small clinical trials suggest that testosterone can improve cognitive function in andropause.
Although such improvement in cognitive function is subtle, patients on testosterone replacement therapy have reported memory improvements in both declarative and procedural domains. In contrast, there is no clinical evidence to date which suggest that the hormone dihydroepiandrosterone (DHEA) can improve cognitive function.
Rises in the levels of the gonadotropins, follicle stimulating hormone (FSH) and luteinizing hormone (LH), have been associated with AD, but the clinical effects of reducing their levels remain to be determined.
We hypothesize that androgens, gonadotropin modulators, or perhaps selective androgen receptor modulators may be useful components of therapy aimed at preventing the onset or delaying the progression of AD in male patients. [/i] Here is the link and download for free:
I choose this study for an oblique reason. In another thread, YoMomma sites an article on DHEA levels and conflates it with DHEA therapeutic benefits. The article above concludes that there is no evidence that DHEA has therapeutic benefit for cognitive disorders of aging--which brings me back to my previous post: epidemiolgy and correlation do not prove causation, let alone therapeutic benefit.
There will and never can be a causative relationship between statistics and conclusions drawn from them. Statistics is not deductive by its very nature.
Science in and of itself is inductive. It only deals with probabilities. Some of the probabilities are so overwhelming that we postulate them as axioms of science. Yet they are not true axioms in the mathematical sense.
When I look at a large study like the British one, I certainly don't think it 'proves' anything. It is not supposed to anyway. Science never 'proves' anything, not being purely deductive.
But just as I no longer smoke cigarettes because of overwhelming statistical evidence that doing so is harmful, I will in the future get my testosterone levels checked and go on TRT when and if the time comes.
First, let me be clear: no straw men were injured in the making of this post.
You may choose to believe what you will, and you may do what you want.
The paper cited is a very good study; but it is not a trial. I offered only a criticism of the use of epidemiology to direct therapy. I cannot recount for you how many good epidemiologic studies show correlations, which when tested in therapeutic trials prospectively, fail miserably.
Despite what you may think, medical trials can indeed prove or disprove the verifiable.
I am not against TRT--I am clearly very much in favor of it where the "burden of evidence" favors it--I am only restating the obvious: this study does not prove that TRT will lower cardiovascular mortality in men.
It is not clear that higher testosterone levels from supplemental testosterone leads to better health in males. It is more likely that males who are genetically predisposed to higher levels of testosterone (aka: Alpha Males) have physiological advantages (protection from disease) over males with lower levels of testosterone.
It is clear (both in primate and in human studies) that males lower on the totem pole have higher levels of stress and higher levels of disease (specifically heart disease).
I believe there is strong evidence that supplemental testosterone is beneficial for the older diabetic male with metabolic syndrome on insulin. This does mean most doctors will start prescribing it for this condition due to fear of potential side affects.
For many others with low testosterone you are right it is not clear. They are at a greater risk of dying. More than one study has shown this. No evidence that I am aware of to prove if supplementing testosterone will help their survival rates but it is worth further study.
Regardless, for the average healthy aging male on this site having doctors routinely and voluntarily prescribing testosterone to keep you at high normal levels is a long way off.