Listing Details
| ID: | 609 |
| Title: | MJ's Human Biology Blog |
| URL: | http://humanbiologyblog.blogspot.com/ |
| Category: | Science: Biology |
| Description: | Highlights recent items in the news or in scientific journal articles that cover new findings and hot topics in human biology. |
| Is "Good" Cholesterol All That Good? - Mon, 21 May 2012 14:06:00 +0000 |
| When it comes to cholesterol in your blood, all cholesterol is not the same. Statistically, people whose blood level of HDL cholesterol - the “good” cholesterol - is in the upper-normal range have reduced risks of developing heart disease. (And conversely, people whose LDL “bad”cholesterol is high have an increased risk of heart disease.) So it only makes sense that you should try to raise your HDL (and lower your LDL), right? This logic is so ingrained in us and in the medical profession that doctors routinely encourage patients with low HDL to change their diet, get more exercise, and take niacin (which is supposed to help raise HDL.) Drug companies have been trying to develop HDL-raising drugs for years - without success, I might add. But nowa new studycasts serious doubt on the “good” cholesterol hypothesis. In the study, researchers reviewed the medical records of subjects with gene variations that cause the subjects to have high HDL levels. They hypothesized that subjects with high HDL because of genetic variations would have a reduced risk of heart disease. To their surprise, a high HDL due to an especially “good” genetic makeup had no effect on risk of heart disease. So what’s going on? No one is arguing against the evidence that a high HDL is associated with a reduced risk of heart disease in normal persons, because it clearly is. But maybe the high HDL is not directly causing the reduced risk. (Remember, an association does not prove cause/effect.) And if a high HDL isn’t directly protective, then raising LDL through drugs or other means would be unlikely to be beneficial. Incidentally, the same may not be true for the risk associated with high LDL, the “bad” cholesterol. Gene variations that caused high LDL levels were associated with increased risk of heart disease, as expected. I’m guessing that this latest paper will lead to more research and a better understanding of the role lipoproteins play in the risk of heart disease. We need to find out, now, what’s actually lowering the risk of heart disease when we observe a high HDL, if in fact it’s not HDL itself.  |
| Does Repetitive Head Trauma Cause Brain Injury? - Thu, 17 May 2012 23:43:00 +0000 |
| On May 2, 2012, NFL linebacker and 12-time Pro-Bowl selection Junior Seau committed suicide. He had retired in 2010 after 20 years in the NFL. His death brings up once again the very real possibility that repetitive head trauma in high-impact sports such as football may lead to a permanent degenerative brain condition called chronic traumatic encephalopathy (CTE.) CTE can lead to depression, loss of memory, dementia, a loss of impulse control, and in the case of at least three ex-football players, perhaps even suicide. Former players are aware that there may be a looming problem with their future health, but no one knows how big the problem could be. One former player, Dave Duerson, allegedly committed suicide specifically so that his brain could be left to science for the study of CTE. A possible association between repetitive head trauma and CTE was first proposed in 2002, when the neurofibrillary tangles that are indicative of CTE were found in the brain of deceased Pittsburgh Steeler center Mike Webster. The National Football League initially downplayed concerns, but when CTE was found in the brains of more than 50 deceased athletes who had participated in high-impact sports, the league changed its tune and has launched a comprehensive study to determine the extent of the problem. Clearly, the NFL is between a rock and a hard place. A good, comprehensive study is sorely needed, but what if it shows that repetitive head trauma does lead to CTE? Many former players are already claiming that the dangers of repetitive head injury were ignored for too long. Over a thousand lawsuits are already pending against the NFL. I’ll keep you posted as evidence for (or against) a causal relationship between head trauma and CTE becomes available. For now, we’re stuck with anecdotal reports, speculation, and of course, lawsuits.  |
| How Long Should You Breast-feed? - Sun, 13 May 2012 11:27:00 +0000 |
| There’s been a lot of talk lately about a philosophy of parenting called attachment parenting. Promulgated largely by a popular child-rearing book called The Baby Book by Dr. William Sears, it’s three main tenets are: 1) breast-feeding, even for several years if mother and child wish 2) co-sleeping (baby sleeps with the parents) and 3) baby-wearing (babies are carried around in slings). The idea is that attachment parenting creates a strong bond between mother and child, so that ultimately the child grows up happier and better-adjusted. Breast-feeding makes sense from a strictly biological perspective, whereas co-sleeping and baby-wearing confer largely psychological benefits. Breast-feeding provides partial immunity to the child against infectious diseases at a time when its immune system is not yet mature, and of course the nutritional value of breast-milk is essentially ideal. The bulk of the benefit of breast-feeding is in the first year, however. The American Academy of Pediatrics recommends that mothers breast-feed exclusively for six months, and then begin to supplement breast-feeding with solid foods until the end of the first year. Breast-feeding beyond the first year is thought to have more social and psychological benefit than biological benefit. How do most mothers measure up? It’s complicated, because not all mothers have either the time or the inclination for attachment parenting or even for breast-feeding, especially if they work. According to the Centers for Disease Control, only 14% of babies are breast-fed exclusively until they are six months old, and only 33% are breast-fed exclusively for even the first three months. But before we get too worked up about these statistics, it’s worth remembering that although most children apparently are not breast-fed according to current recommendations, and there’s no convincing evidence that they are somehow disadvantaged as a result. So my suggestion would be that you follow the American Academy of Pediatrics guidelines if you can, but don’t feel too guilty if you can’t.  |