Yet another disappointing news...there have been no good study defining lifestyle changes and how it affects the diabetes control among children and adolescents. even though there have been over 4000 articles written about it.. it is a sad commentary that Diabetes has become fashionable but no one seems to have a good approach to it.. or it is being pressured from other social forces.. Food Industry, Pharmaceutical Industry etc just to think about it..
In search of quality evidence for lifestyle management and glycemic control in children and adolescents with type 2 diabetes: A systematic review
Steve T Johnson email, Amanda S Newton email, Meera Chopra email, Jeanette Buckingham email, Terry T-K Huang email, Paul W Franks email, Mary M Jetha email and Geoff DC Ball email
BMC Pediatrics 2010, 10:97doi:10.1186/1471-2431-10-97
There is no high quality evidence to suggest lifestyle modification improves either short- or long-term glycemic control in children and youth with T2D. Additional research is clearly warranted to define optimal lifestyle behaviour strategies for young people with T2D.
Monday, 27 December 2010
Tuesday, 21 December 2010
Better to Exercise Before Breakfast: The Yogic Way as well
Phys Ed: The Benefits of Exercising Before Breakfast
By GRETCHEN REYNOLDSIan Spanier/Getty Images
The holiday season brings many joys and, unfortunately, many countervailing dietary pitfalls. Even the fittest and most disciplined of us can succumb, indulging in more fat and calories than at any other time of the year. The health consequences, if the behavior is unchecked, can be swift and worrying. A recent study by scientists in Australia found that after only three days, an extremely high-fat, high-calorie diet can lead to increased blood sugar and insulin resistance, potentially increasing the risk for Type 2 diabetes. Waistlines also can expand at this time of year, prompting self-recrimination and unrealistic New Year’s resolutions.
But a new study published in The Journal of Physiology suggests a more reliable and far simpler response. Run or bicycle before breakfast. Exercising in the morning, before eating, the study results show, seems to significantly lessen the ill effects of holiday Bacchanalias.
For the study, researchers in Belgium recruited 28 healthy, active young men and began stuffing them with a truly lousy diet, composed of 50 percent fat and 30 percent more calories, overall, than the men had been consuming. Some of the men agreed not to exercise during the experiment. The rest were assigned to one of two exercise groups. The groups’ regimens were identical and exhausting. The men worked out four times a week in the mornings, running and cycling at a strenuous intensity. Two of the sessions lasted 90 minutes, the others, an hour. All of the workouts were supervised, so the energy expenditure of the two groups was identical.
Their early-morning routines, however, were not. One of the groups ate a hefty, carbohydrate-rich breakfast before exercising and continued to ingest carbohydrates, in the form of something like a sports drink, throughout their workouts. The second group worked out without eating first and drank only water during the training. They made up for their abstinence with breakfast later that morning, comparable in calories to the other group’s trencherman portions.
The experiment lasted for six weeks. At the end, the nonexercising group was, to no one’s surprise, super-sized, having packed on an average of more than six pounds. They had also developed insulin resistance — their muscles were no longer responding well to insulin and weren’t pulling sugar (or, more technically, glucose) out of the bloodstream efficiently — and they had begun storing extra fat within and between their muscle cells. Both insulin resistance and fat-marbled muscles are metabolically unhealthy conditions that can be precursors of diabetes.
The men who ate breakfast before exercising gained weight, too, although only about half as much as the control group. Like those sedentary big eaters, however, they had become more insulin-resistant and were storing a greater amount of fat in their muscles.
Only the group that exercised before breakfast gained almost no weight and showed no signs of insulin resistance. They also burned the fat they were taking in more efficiently. “Our current data,” the study’s authors wrote, “indicate that exercise training in the fasted state is more effective than exercise in the carbohydrate-fed state to stimulate glucose tolerance despite a hypercaloric high-fat diet.”
Just how exercising before breakfast blunts the deleterious effects of overindulging is not completely understood, although this study points toward several intriguing explanations. For one, as has been known for some time, exercising in a fasted state (usually possible only before breakfast), coaxes the body to burn a greater percentage of fat for fuel during vigorous exercise, instead of relying primarily on carbohydrates. When you burn fat, you obviously don’t store it in your muscles. In “our study, only the fasted group demonstrated beneficial metabolic adaptations, which eventually may enhance oxidative fatty acid turnover,” said Peter Hespel, Ph.D., a professor in the Research Center for Exercise and Health at Catholic University Leuven in Belgium and senior author of the study.
At the same time, the fasting group showed increased levels of a muscle protein that “is responsible for insulin-stimulated glucose transport in muscle and thus plays a pivotal role in regulation of insulin sensitivity,” Dr Hespel said.
In other words, working out before breakfast directly combated the two most detrimental effects of eating a high-fat, high-calorie diet. It also helped the men avoid gaining weight.
There are caveats, of course. Exercising on an empty stomach is unlikely to improve your performance during that workout. Carbohydrates are easier for working muscles to access and burn for energy than fat, which is why athletes typically eat a high-carbohydrate diet. The researchers also don’t know whether the same benefits will accrue if you exercise at a more leisurely pace and for less time than in this study, although, according to Leonie Heilbronn, Ph.D., a professor at the University of Adelaide in Australia, who has extensively studied the effects of high-fat diets and wrote a commentary about the Belgian study, “I would predict low intensity is better than nothing.”
So, unpleasant as the prospect may be, set your alarm after the next Christmas party to wake you early enough that you can run before sitting down to breakfast. “I would recommend this,” Dr. Heilbronn concluded, “as a way of combating Christmas” and those insidiously delectable cookies.
Mediator Benfluorex FenFluoramine hits the Dust
Yet another miracle drug hits the dust..
after multiple warnings from the watchdogs, the final study by the epidemiologists from Villejuif hospital has confirmed that around 2000 people in France have died after taking the medication, Mediator..
This particular drug had been banned in the USA but the French kept them on despite mounting evidence of deaths and the doctors continued to prescribe them.
I wonder why two such pharamaceutically advanced countries differ from each other: Avandia is banned in France but allowed to be prescribed in the USA.. in general USA seems to have a more publicized approach to the drugs..
In any case, one by one many of the new touted miracle drugs are getting the exit sign..perhaps it is like describing all the beaches in every country as Paradise on earth, there are just few outstanding beaches... there are drugs which are extraordinary such as Aspirin and the concocted ones which treat an array of symptoms and some people get better. Most of the Oral Anti Diabetes drugs and including injectable drugs such as Byetta (but not insulin ) fall into this category.. In the end, what is new may not be the best, what is tried and proven may be.. such as Insulin introduced 70+ years ago and Aspirin introduced in the 19th century? French scientist Gerhardt 1853!
after multiple warnings from the watchdogs, the final study by the epidemiologists from Villejuif hospital has confirmed that around 2000 people in France have died after taking the medication, Mediator..
This particular drug had been banned in the USA but the French kept them on despite mounting evidence of deaths and the doctors continued to prescribe them.
I wonder why two such pharamaceutically advanced countries differ from each other: Avandia is banned in France but allowed to be prescribed in the USA.. in general USA seems to have a more publicized approach to the drugs..
In any case, one by one many of the new touted miracle drugs are getting the exit sign..perhaps it is like describing all the beaches in every country as Paradise on earth, there are just few outstanding beaches... there are drugs which are extraordinary such as Aspirin and the concocted ones which treat an array of symptoms and some people get better. Most of the Oral Anti Diabetes drugs and including injectable drugs such as Byetta (but not insulin ) fall into this category.. In the end, what is new may not be the best, what is tried and proven may be.. such as Insulin introduced 70+ years ago and Aspirin introduced in the 19th century? French scientist Gerhardt 1853!
Friday, 17 December 2010
New York Times 1903 Cuba and the Indians
In this long, well researched and interesting article published in 1903 under the title Cuba Past and Present, the history of spanish colonization and the gradual disappearance of the Indians of Cuba is documented. In fact the sub heading is: No member of the Race which greeted Columbus can be found in the island.If there were no Indians in Cuba in 1903 where did they suddenly appear from in 1983 when Cuban born European researchers from Camaguey living in the USA and Mulattos raised in Puerto Rico and New York began "researching" the Indians in Cuba with local cultural prostitutes or jinateros?
Why dont these people come to Cuba and meet up with the Ministry of Culture and present their case for the presence of the Indians in Cuba and solve this questions once and for all? The current minister of Culture in Cuba is Mr Abel Prieto a well educated and well traveled Cuban with an extremely open mind and I am sure he will be willing to listen to these New Indians.
I shall wait to hear of such a meeting so that I can myself correct my understanding or confirm it.
Monday, 29 November 2010
Society, Poverty and Sickness.... too long a list but neglected by Doctors
In a recent article out of Canada, they found out that age at menarche varied according to the socioeconomic status: poorer children had their first menstruation earlier and absence of father was also a cause.
When we talk about Poverty and diseases of Civilization, we are mainly talking about the West and wannabee West countries like Malaysia and Singapour.. It is well known that degenerative diseases such as Diabetes and Hypertension affect the poor more than the rich. Epidemiologists have done disservice to the public and the propagation of Health in general by perfecting their tools to find the answer they want. That is why currently up to 90 per cent of the scientific articles have to be scrutinized for truth because most of them have assumed false circumstances and thus produce false results. Few years ago they found out that taking calcium supplements are useless in preventing osteoporotic fractures that is before we found out that almost every one living in the west is low in Vitamin D and thus lacking an absorption mechanism for Calcium.
I have always maintained that Cholesterol is a marker of Inflammation in the body and that Statins the expensive medications that do bring the levels of cholesterol have also an antiinflammatory effects but we dont hear about new anti inflammatory drugs since there is profit in statin medications. there is a lawsuit pending against Pfizer the manufacturer of anti cholesterol medication Lipitor for falsifying some tabulative procedures by bribing the researchers and national organizations... oh what a world we are living in.. surrounded by vultures feeding on the carrions..
when I began my work with American Indians, truly one of the last of the colonized people on the earth, many elders got up to speak at a Prevention of Diabetes symposium at their Lakota Reservation.. Give us Jobs, that would take care of Diabetes the elders intoned.. and you can look at the employment figures and diabetes rates all through the Indian Country, one of the best is the example given in the book Diabetes: The Sugar coated Crisis by that tireless crusader, David Spero, two bands of the Cuahuilla nation, the Morongo and the Torres-Martinez. The latter has four times the rate of Diabetes than the former who is fairly well off due to a well run Casino in their Reservation.. Most everyone working with the First Nations know of the Epidemiological Hijacking of the Pima Nation of the USA and very little attention paid to the fact that their relatives the Pima of Mexico suffer from much less (incredibly much less) of the Diabetes and other metabolic disorders which the researchers have made them famous for.
Suffering among human beings cannot be objectified to certain physiological phenomenon. Whenever you see fantastic claims of a medical breakthrough or a magic of a single nutritional ingredient, be skeptical.
In this world of human exploitation, be very cynical about its messengers who are now Professors at Medical Schools in USA and their lackeys in UK and Australia. If they are pushing drugs, that is what they are: Drug pushers. and there are many who have made a name for themselves while harming immense number of women, by trying to make Menopause a disease and let us hope that we wont allow them to do the same by making Menarche a disease by objectifying it into physiology without taking into consideration the social and economic impacts.
When we talk about Poverty and diseases of Civilization, we are mainly talking about the West and wannabee West countries like Malaysia and Singapour.. It is well known that degenerative diseases such as Diabetes and Hypertension affect the poor more than the rich. Epidemiologists have done disservice to the public and the propagation of Health in general by perfecting their tools to find the answer they want. That is why currently up to 90 per cent of the scientific articles have to be scrutinized for truth because most of them have assumed false circumstances and thus produce false results. Few years ago they found out that taking calcium supplements are useless in preventing osteoporotic fractures that is before we found out that almost every one living in the west is low in Vitamin D and thus lacking an absorption mechanism for Calcium.
I have always maintained that Cholesterol is a marker of Inflammation in the body and that Statins the expensive medications that do bring the levels of cholesterol have also an antiinflammatory effects but we dont hear about new anti inflammatory drugs since there is profit in statin medications. there is a lawsuit pending against Pfizer the manufacturer of anti cholesterol medication Lipitor for falsifying some tabulative procedures by bribing the researchers and national organizations... oh what a world we are living in.. surrounded by vultures feeding on the carrions..
when I began my work with American Indians, truly one of the last of the colonized people on the earth, many elders got up to speak at a Prevention of Diabetes symposium at their Lakota Reservation.. Give us Jobs, that would take care of Diabetes the elders intoned.. and you can look at the employment figures and diabetes rates all through the Indian Country, one of the best is the example given in the book Diabetes: The Sugar coated Crisis by that tireless crusader, David Spero, two bands of the Cuahuilla nation, the Morongo and the Torres-Martinez. The latter has four times the rate of Diabetes than the former who is fairly well off due to a well run Casino in their Reservation.. Most everyone working with the First Nations know of the Epidemiological Hijacking of the Pima Nation of the USA and very little attention paid to the fact that their relatives the Pima of Mexico suffer from much less (incredibly much less) of the Diabetes and other metabolic disorders which the researchers have made them famous for.
Suffering among human beings cannot be objectified to certain physiological phenomenon. Whenever you see fantastic claims of a medical breakthrough or a magic of a single nutritional ingredient, be skeptical.
In this world of human exploitation, be very cynical about its messengers who are now Professors at Medical Schools in USA and their lackeys in UK and Australia. If they are pushing drugs, that is what they are: Drug pushers. and there are many who have made a name for themselves while harming immense number of women, by trying to make Menopause a disease and let us hope that we wont allow them to do the same by making Menarche a disease by objectifying it into physiology without taking into consideration the social and economic impacts.
Thursday, 25 November 2010
Sex and Gender Specific Research in Medicine
Analysis of sex and gender-specific research reveals a common increase in publications and marked differences between disciplines
Sabine Oertelt-Prigione 
BMC Medicine 2010, 8:70doi:10.1186/1741-7015-8-70
| Published: | 10 November 2010 |
Abstract (provisional)
Background
The incorporation of sex and gender-specific analysis in medical research is increasing due to pressure from public agencies, funding bodies, and the clinical and research community. However, generation of knowledge and publication trends in this discipline are currently spread over distinct specialties and difficult to analyze comparatively.
Methods
Using a text-mining approach, we have analyzed sex and gender aspects in research within nine clinical subspecialties - Cardiology, Pulmonology, Nephrology, Endocrinology, Gastroenterology, Haematology, Oncology, Rheumatology, Neurology - using six paradigmatic diseases in each one. Articles have been classified into five pre-determined research categories - Epidemiology, Pathophysiology, Clinical research, Management and Outcomes. Additional information has been collected on the type of study (human/animal) and the number of subjects included. Of the 8,836 articles initially retrieved, 3,466 (39%) included sex and gender-specific research and have been further analyzed.
Results
Literature incorporating sex/gender analysis increased over time and displays a stronger trend if compared to overall publication increase. All disciplines, but cardiology (22%), demonstrated an underrepresentation of research about gender differences in management, which ranges from 3 to 14%. While the use of animal models for identification of sex differences in basic research varies greatly among disciplines, studies involving human subjects are frequently conducted in large cohorts with more than 1000 patients (24% of all human studies).
Conclusions
Heterogeneity characterizes sex and gender-specific research. Although large cohorts are often analyzed, sex and gender differences in clinical management are insufficiently investigated leading to potential inequalities in health provision and outcomes.
Tuesday, 23 November 2010
Decreasing Testosterone levels in the USA
In one of the largest study of its kind, Travison et al. report a population-wide decline in Massachusetts's men’s testosterone levels during the last 20 years that is not related to normal aging or to health and lifestyle factors known to influence testosterone levels.
They found that testosterone concentrations dropped about 1.2% per year, or about 17% overall, from 1987 to 2004. The downward trend was seen in both the population and in individuals over time.
The decline is consistent with other long-term trends in male reproductive health, including decreases in sperm quality and increases in testicular cancer, hypospadias and cryptorchidism.
The strongest association was observed in same-aged men from different sampling years. For example, a 65-year-old in 2002 had lower testosterone levels than a 65-year-old in 1987.
Lower concentrations of testosterone can increase a man’s risk for age-related diseases, depression and infertility.
Also, the younger and older men in the study experienced similar hormone declines that dropped faster than would be predicted by normal aging.
Context: In men, the hormone testosterone guides behavior and reproduction. It controls growth and development of sex organs and other typically male characteristics, such as facial hair and a deep voice.
Normally, levels fluctuate from conception through puberty then level out during adulthood before declining as men age. Some chronic health problems typically seen in older adults, such as diabetes, depression and obesity, are associated with lower testosterone levels.
Recent studies have that found environmental impacts on testosterone levels. For example, testosterone levels were lower in US Air Force veterans exposed to dioxins while spraying Agent Orange during the Vietnam War, as well as in men exposed to phthalates at work.
What did they do?
Travison et al. used blood hormone data and personal information collected from men living in Boston, MA, as part of the Massachusetts Male Aging Study (MMAS). The MMAS examined men’s health and endocrine function. Data were gathered during three home visits from 1987-89 (T1), 1995-97 (T2), and 2002-04 (T3). Total testosterone (TT) and serum sex hormone-binding globulin were measured in the blood and available testosterone (BT) was calculated. The men self-reported such things as basic demographics, health status, and smoking and alcohol use.
In this study, Travison et al. analyzed data from 1,532 men (1,383, 955, and 568, respectively, from T1, T2 and T3) that met age and birth year requirements. Participants ranged from 45 to 79 years old and were born between 1916 and 1945. The researchers excluded high and low T levels, missing data, and unidentified prostate cancer treatment. Within the sample, they calculated and compared three separate but related associations among concentration, age, and time. They looked at changes in testosterone concentrations in the group of men at different years and ages associated with T1, T2, and T3; testosterone declines in individual men as they aged during the study; and testosterone concentrations of men of the same age but in different years (age-matched).
What did they find?
Travison et al. found strong evidence of a decline of more than 1% per year in men’s blood testosterone levels during the last two decades. The graph to the right shows average levels for each for men of different ages in each of the three measurement periods (T1-T3).
Dotted lines are 95% confidence bands. Adapted from Travison et al.
Testosterone decline
The first comparison to make is that within a cohort, older men tend to have lower testosterone levels. Compare, for example, 80 yr old men in T3 compared to 60 yr old men.
The crucial comparison to make is from one cohort to the next, comparing men of the same age. For example, 60 yr old men during the first measurement period (red line, 1987-1989) had total testosterone levels over 500 ng/dL. Men aged 60 yrs old in the third cohort (blue line, measured 2002-2004) had TT below 450 ng/dL. There is no overlap between the confidence bands of T1 vs T3: T3 (measured 2002-2004) is always lower than T1.
The trend holds regardless of the men’s age. Similar declines over the 17 years were seen in all ages of men in the study.
Travison et al. note that the decline within the cohorts related to age is less than the decrease observed across cohorts. For example, men aged 70 in T1 had TT only 6% less than men aged 45 in the same cohort. But 60 yr old men in T3 had TT concentration approximately 13% lower than men the same age in T1.
To illustrate this point another way, Travison et al. compared the average decline of testosterone levels in T1 vs T2 as a function of age, and then contrast that with differences in testosterone between men of the same age in T1 vs T2. Note that T1 and T2 were only separated by 9 years. The average declines in T1 and T2 per decade of life were 17 and 20 ng/mL, respectively. But 65 yr old men in T2 had total testosterone levels 50 ng/mL lower than those in T1, even though the samples were separated by less than a decade.
Travison et al. then estimated the decline over time, from the first cohort to the third, for men of the same age (what they called the age-matched decline). They found that testosterone declined by 1.2% per year (95% CI 1.0% to 1.4%).
Bioavailable testosterone (BT) also showed similar declines over time. The strongest associations again held for age-matched trends with declines of 1.3% per year (95% CI 1.7% - 1.1%).
None of the health and lifestyle factors examined were associated with either age-matched declines in either TT or BT: The age-matched declines remained essentially the same after controlling for chronic illness, general health, medications, smoking, body mass index, employment, marital status, and other indicators.
Finally, the trends held when analyzing the data in a number of different ways, including by interview date, study cohort, restricting to men of certain ages or birth cohorts, and considering incomplete versus complete data.
What does it mean?
Travison et al. find that testosterone levels declined in Massachusetts men by approximately 1.2% per year from the late 1980s through 2004, controlling for the age of the men and other possible confounding variables.
This study is important because of its large sample size and long duration. Few studies have looked directly at testosterone levels over time.
The results are surprisingly consistent with another set of long-term human epidemiology studies. Those studies also show a long-term decline in male reproductive functions, such as decreased sperm health and increased infertility, which are highly associated with or controlled by testosterone and other androgen hormones. The rate of decline reported in this study is roughly comparable to the rate of decline of sperm count reported first by Carlson et al. in 1992 and then reanalyzed by Swan et al.in 2000.
In commentary accompanying Travison et al.'s study in the Journal of Clinical Endocrinology and Metabolism, Dr. Shalender Bhasin (Boston Medical Center) writes: The data in this study are "important because they provide independent support for the concerns raised earlier about the reproductive health of men." ... "it would be unwise to dismiss these reports as mere statistical aberrations because of the potential threat these trends-- if confirmed-- pose to the survival of the human race and other living residents of our planet."
They found that testosterone concentrations dropped about 1.2% per year, or about 17% overall, from 1987 to 2004. The downward trend was seen in both the population and in individuals over time.
The decline is consistent with other long-term trends in male reproductive health, including decreases in sperm quality and increases in testicular cancer, hypospadias and cryptorchidism.
The strongest association was observed in same-aged men from different sampling years. For example, a 65-year-old in 2002 had lower testosterone levels than a 65-year-old in 1987.
Lower concentrations of testosterone can increase a man’s risk for age-related diseases, depression and infertility.
Also, the younger and older men in the study experienced similar hormone declines that dropped faster than would be predicted by normal aging.
Context: In men, the hormone testosterone guides behavior and reproduction. It controls growth and development of sex organs and other typically male characteristics, such as facial hair and a deep voice.
Normally, levels fluctuate from conception through puberty then level out during adulthood before declining as men age. Some chronic health problems typically seen in older adults, such as diabetes, depression and obesity, are associated with lower testosterone levels.
Recent studies have that found environmental impacts on testosterone levels. For example, testosterone levels were lower in US Air Force veterans exposed to dioxins while spraying Agent Orange during the Vietnam War, as well as in men exposed to phthalates at work.
What did they do?
Travison et al. used blood hormone data and personal information collected from men living in Boston, MA, as part of the Massachusetts Male Aging Study (MMAS). The MMAS examined men’s health and endocrine function. Data were gathered during three home visits from 1987-89 (T1), 1995-97 (T2), and 2002-04 (T3). Total testosterone (TT) and serum sex hormone-binding globulin were measured in the blood and available testosterone (BT) was calculated. The men self-reported such things as basic demographics, health status, and smoking and alcohol use.
In this study, Travison et al. analyzed data from 1,532 men (1,383, 955, and 568, respectively, from T1, T2 and T3) that met age and birth year requirements. Participants ranged from 45 to 79 years old and were born between 1916 and 1945. The researchers excluded high and low T levels, missing data, and unidentified prostate cancer treatment. Within the sample, they calculated and compared three separate but related associations among concentration, age, and time. They looked at changes in testosterone concentrations in the group of men at different years and ages associated with T1, T2, and T3; testosterone declines in individual men as they aged during the study; and testosterone concentrations of men of the same age but in different years (age-matched).
What did they find?
Travison et al. found strong evidence of a decline of more than 1% per year in men’s blood testosterone levels during the last two decades. The graph to the right shows average levels for each for men of different ages in each of the three measurement periods (T1-T3).
Dotted lines are 95% confidence bands. Adapted from Travison et al.
Testosterone decline
The first comparison to make is that within a cohort, older men tend to have lower testosterone levels. Compare, for example, 80 yr old men in T3 compared to 60 yr old men.
The crucial comparison to make is from one cohort to the next, comparing men of the same age. For example, 60 yr old men during the first measurement period (red line, 1987-1989) had total testosterone levels over 500 ng/dL. Men aged 60 yrs old in the third cohort (blue line, measured 2002-2004) had TT below 450 ng/dL. There is no overlap between the confidence bands of T1 vs T3: T3 (measured 2002-2004) is always lower than T1.
The trend holds regardless of the men’s age. Similar declines over the 17 years were seen in all ages of men in the study.
Travison et al. note that the decline within the cohorts related to age is less than the decrease observed across cohorts. For example, men aged 70 in T1 had TT only 6% less than men aged 45 in the same cohort. But 60 yr old men in T3 had TT concentration approximately 13% lower than men the same age in T1.
To illustrate this point another way, Travison et al. compared the average decline of testosterone levels in T1 vs T2 as a function of age, and then contrast that with differences in testosterone between men of the same age in T1 vs T2. Note that T1 and T2 were only separated by 9 years. The average declines in T1 and T2 per decade of life were 17 and 20 ng/mL, respectively. But 65 yr old men in T2 had total testosterone levels 50 ng/mL lower than those in T1, even though the samples were separated by less than a decade.
Travison et al. then estimated the decline over time, from the first cohort to the third, for men of the same age (what they called the age-matched decline). They found that testosterone declined by 1.2% per year (95% CI 1.0% to 1.4%).
Bioavailable testosterone (BT) also showed similar declines over time. The strongest associations again held for age-matched trends with declines of 1.3% per year (95% CI 1.7% - 1.1%).
None of the health and lifestyle factors examined were associated with either age-matched declines in either TT or BT: The age-matched declines remained essentially the same after controlling for chronic illness, general health, medications, smoking, body mass index, employment, marital status, and other indicators.
Finally, the trends held when analyzing the data in a number of different ways, including by interview date, study cohort, restricting to men of certain ages or birth cohorts, and considering incomplete versus complete data.
What does it mean?
Travison et al. find that testosterone levels declined in Massachusetts men by approximately 1.2% per year from the late 1980s through 2004, controlling for the age of the men and other possible confounding variables.
This study is important because of its large sample size and long duration. Few studies have looked directly at testosterone levels over time.
The results are surprisingly consistent with another set of long-term human epidemiology studies. Those studies also show a long-term decline in male reproductive functions, such as decreased sperm health and increased infertility, which are highly associated with or controlled by testosterone and other androgen hormones. The rate of decline reported in this study is roughly comparable to the rate of decline of sperm count reported first by Carlson et al. in 1992 and then reanalyzed by Swan et al.in 2000.
In commentary accompanying Travison et al.'s study in the Journal of Clinical Endocrinology and Metabolism, Dr. Shalender Bhasin (Boston Medical Center) writes: The data in this study are "important because they provide independent support for the concerns raised earlier about the reproductive health of men." ... "it would be unwise to dismiss these reports as mere statistical aberrations because of the potential threat these trends-- if confirmed-- pose to the survival of the human race and other living residents of our planet."
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