Monday, November 4, 2013

Health Research Recap (Week of 10/28/2013)

A large review of the research found a strong relationship between physical activity and depression.  Even exercising for only 20 minutes a day may be able to treat or prevent depression.  Part of this effect is due to exercise stimulating brain neurogensis by the secretion of BDNF, a protein that supports the survival of neurons and helps create new ones.  Another study found even DIY activities such as gardening significantly reduce heart disease risk.  A third study found aerobic exercise to improve brain function in people with multiple sclerosis.  The study found a 54% improvement in memory function and 17% increase in hippocampal volume in 2 subjects with multiple sclerosis that performed 30 minutes of aerobic exercise 3 times a week for 3 months.  Since this is such a small study, further studies will be needed to confirm these findings.

Young athletes who specialize in one sport or play more hours per week than their age are more likely to get injured.  The study found, specifically, that kids who spent twice as much time playing a single sport than engaging in free play were more likely to become injured, especially with overuse injuries.  This is because playing the same sport over and over utilizes the same movement patterns while neglecting other movements.  Playing multiple sports that utilize many motor patterns and engaging in activities not directly related to their sport gives kids an opportunity to develop better overall as an athlete.  It also gives the tissues that are frequently used in their sport an opportunity to recover.

In cardiovascular news, people with rheumatoid arthritis are at a higher risk of cardiovascular disease.  The culprit?  The inflammation associated with the condition.  Rheumatoid arthritis, an autoimmune disease, is characterized by large levels of inflammation and the study found that the more severe a person's RA upon diagnosis, the more likely that person will experience cardiovascular disease.  This comes to no surprise for many researchers.  While most of America tries to lower their cholesterol for no apparent reason, science has long been looking at the effects of inflammation on cardiovascular disease.  The problem doesn't appear to be a cholesterol issue.  Cholesterol is vitally important to human physiology, but when chronic inflammation oxidizes cholesterol, it becomes "sticky" and can cling to areas of bifurcation, where 2 arteries come together to form one.

Another study found an association between people with Alzheimer's disease and an increased risk of cardiovascular disease.  This link should come as no surprise, another study found genes associated with increased immune activity in people with Alzheimer's disease, and other research is beginning to point to Alzheimer's disease as an autoimmune condition, much like RA.

A study looking at the relationship between Alzheimer's disease and high blood glucose levels confirms the link that other research has shown between the two.  When blood vessels in the brain were exposed to either high blood glucose or the beta amyloid plaques associated with the disease, there was no change in the viability of the vessels.  However, when the blood vessels were exposed to both high blood glucose and beta amyloid, the viability of the blood vessels decreased by 40%.  The researchers believe the effect is due to a compromised blood brain barrier from beta amyloid plaques and increased oxidative stress from the mitochondria when blood glucose levels are high.
In somewhat related news, researchers found an interesting link between HDL, the so called good cholesterol, and blood glucose control.  The researchers found that raising HDL cholesterol improves blood glucose control by enhancing the ability of skeletal muscle to use glucose.  In animal models, increasing HDL cholesterol protected against hyperglycemia and resulted in improved mitochondrial function as evidenced by a reduction in a marker for mitochondrial dysfunction.  How can one increase their HDL cholesterol?  Being more active and consuming saturated fat are both natural ways to increase your HDL cholesterol.

Gravity doesn't get a lot of play in the media, but don't let that downplay it's importance to human physiology.  Astronauts in microgravity experience increased oxidative stress and inflammation, leading to an increase in aging as well as cardiovascular disease risk.  These findings help show how important gravity is to human health.  If you don't think this pertains to you since you're not an astronaut, think again.  In a past study , researchers found that being in a position where one of your legs was not loaded(Aka sitting) and the other one was led to downregulation of genes associated with antioxidant and anti-inflammatory activity in the unloaded leg compared to the loaded one.  In another study, breaking up periods of sitting with standing led to increased activity of anti-inflammatory and antioxidant gene pathways in the lower body.  In other words, get off your butt.

Finally, in the "This is how research can be manipulated to say what we want" category, researchers claim to have determined that sugar does not lead to non-alcoholic fatty liver disease.  The study found that it is excessive calorie consumption and not consumption of fructose or glucose that leads to NAFLD.  If you take a close look at the study, it doesn't actually show what the authors state.  Subjects were randomized to either a high glucose or high fructose diet and consumed a number of calories that would not cause them to gain weight.  After a washout period, they then consumed the same diet with an excess number of calories.  Neither one led to increased liver fat in the calorie maintenance condition while both led to increased liver fat in the hypercaloric condition.  The problem with this study?  For one, the diets were only consumed over 2 weeks so we don't know if there is a long term effect of these diets in an isocaloric condition.  There was an increase in insulin resistance in the high fructose condition that may have worsened over time.  Second, there was no control diet for both conditions to see if the absence of both glucose and fructose in a hypercaloric diet led to an increase in liver fat.  What this study actually shows is that consumption of a high fructose or high glucose diet while at the same time overconsuming calories increases the risk of NAFLD.  This doesn't exonerate glucose or fructose, it only states that consuming them in moderation is probably not going to lead to NAFLD.  The question is, do people who consume a high fructose or high glucose diet tend to eat at maintenance calories, my guess is not.  Ironically enough, one of the researchers is on the scientific advisory board of Mars, inc. and Coca Cola.