{"id":368,"date":"2015-04-29T03:13:16","date_gmt":"2015-04-29T03:13:16","guid":{"rendered":"http:\/\/joshmitteldorf.peachpuff-wolverine-566518.hostingersite.com\/?p=368"},"modified":"2015-05-06T16:04:29","modified_gmt":"2015-05-06T16:04:29","slug":"large-new-survey-tracks-telomere-length-and-mortality","status":"publish","type":"post","link":"https:\/\/scienceblog.com\/joshmitteldorf\/2015\/04\/29\/large-new-survey-tracks-telomere-length-and-mortality\/","title":{"rendered":"Large New Survey Tracks Telomere Length and Mortality"},"content":{"rendered":"

Last week, a Danish study<\/a> was published that tracked 65,000 people over a median of 7 years. \u00a0The bottom line was that telomere length robustly predicts longevity, even after factoring out the effect of age, smoking, exercise, blood cholesterol, BMI, and alcohol consumption. \u00a0This adds immensely to our knowledge of telomere length and its predictive power. \u00a0For perspective, the original [2003<\/a>] study by Cawthon detected the relationship between telomere length and mortality based on fewer than 200 subjects.<\/p>\n

The new data set is large enough to show trends over all of the health-related lifestyle variables. \u00a0Smoking, inactivity, weight (body mass index), and alcohol consumption all correlated negatively with telomere length. \u00a0So it should not be surprising that blood pressure and LDL choloesterol also correlated negatively with telomere length, and it is then a foregone conclusion that mortality must correlate negatively with telomere length. \u00a0This demonstrates without a doubt that unhealthy behaviors lead to shorter telomeres, as Epel and Blackburn have been telling us for a decade. \u00a0(They have emphasized the converse: that healthy life choices lead to longer, healthier life through the medium of longer telomeres [Ref<\/a>, Ref<\/a>, Ref<\/a>, Ref<\/a>]).<\/p>\n

The bottom line of the new, large study is the extra<\/i> predictive power of telomere length, even after all these other lifestyle and indicator variables are factored out. \u00a0Correcting for smoking, correcting for age, correcting for weight and cholesterol and exercise habits, there is still a powerful negative correlation between telomere length and mortality. \u00a0The shorter your telomeres, the greater your chance of dying. \u00a0The 10% of people with the shortest telomeres were dying at 1.4 the rate of the 10% with the longest telomeres, a result that was overwhelmingly statistically apparent (p<2×10-15<\/sup>).<\/p>\n\n\n\n
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Are Short Telomeres a Cause of Aging or Just a Marker of Aging?<\/b><\/p>\n

There are many traits associated with aging that are mere markers. \u00a0For example, grey hair is associated with aging, but you don\u2019t expect that coloring your hair will lead to longer life span. \u00a0Even if you found a treatment that restored your hair color by rejuvenating the pigment in your follicles, you wouldn\u2019t expect to live longer as a result.<\/p>\n

On the other hand, inflammation increases with age, and we know that it is not just a marker but a cause. \u00a0Reducing inflammation leads to longer life.<\/p>\n

So are short telomeres like hair color or like inflammation? \u00a0Can we reasonably expect that lengthening telomeres will lengthen life?<\/p>\n

Many lab scientists (and some gerontologists) think that it can\u2019t be so easy to combat aging. \u00a0Theory says that if telomerase could increase life span, then evolution would have granted us more telomerase. \u00a0After all, the hTERT gene is already there in every cell, the metabolic cost of producing it is inconsequential. \u00a0Telomerase is free, and it can be released with the turn of a metabolic switch.<\/p>\n

The theory continues: we know that diseases, lacerations, stresses all require more cell replication to repair them. \u00a0This must leave telomeres shorter than they would be otherwise. Smoking and inflammation are also known to shorten telomeres. \u00a0So (by this reasoning) people with shorter telomeres are expected to have shorter life expectancy because the shorter telomeres are telling a story that the person has suffered more stress. \u00a0Short telomeres are only a symptom of aging, and not a cause.<\/p>\n

This new Danish study puts this theory to rest. \u00a0At last there is enough data that corrections can be made for smoking, obesity, exercise, and all major life style variables that could conceivably be have an impact on mortality comparable to the large effect we find associated with telomere length.<\/p>\n

The correction is done using a statistical method called ANOVA, which can partition the causes of mortality into statistical bins and say how much is due to smoking, how much is due to blood cholesterol, how much is due to age, and how much is due to telomere shortening.<\/p>\n

Results from the study:<\/p>\n