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Jul 21

Through my various scattered readings I thought I had found a link between obesity and going into debt due to neuro-chemical changes in the brain. Two new reports prompted me to re-ponder the link at the population level between the rise of obesity and the rise of consumer debt.

CDC (center of disease control and prevention) released the latest obesity numbers (2007) here. One of their own objective as part of “Healthy people 2010″ project is to reduce the percentage of obesity to 15%. Well, only one state even fell into  the range of 15-19% obesity, which was Colorado at 18.7%. It looks like there is a lot of work (exercise) ahead if America has any hope of reaching this goal by 2010. I personally do not believe even one state will reach this goal let along all 50. The data supports the opposite, as 45 of the 50 states obesity rate increased. Overall, the obesity rate increased to 25.6%, which is 1.7% higher than 2 years ago. Wrong direction. The other startling fact which I did not know is this set of data is gathered by phone interviews and use ’self-reported’ weight and height. CDC understands the potential problem with self reported weight and height and therefore estimate the real obesity rate is more likely to be 34% (as reported here). Add the percentage of overweight adults to the 34% obese and you are in the range of greater than 66% (see here). Below is one graph that I found that show the obesity trend over time.

Now let us switch gears and look at consumer debt.

NY times had a piece this weekend on the rise of consumer debt. You can see in this interactive graph on the NY times site the the ratio of savings (beige - top of graph) versus debt (blue variations - bottom of graph) is not going in the right direction (though I am sure some economists could come up with an opposite argument).

What is interesting for this blog piece is what appears to be a nice correlation between the rise of obesity and the rise of consumer debt (and reduced savings).

Does a full stomach, increased fat storage, and all the subsequent (and possibly changes that occur in the brain prior to the increase of fat storage - potential cause) changes that occur in the brain (I will go into the details in another piece) make the body/brain feel ‘full’ and hence no need to ’save’ for a rainy day because the ’store’ is full? Can you afford to spend (and borrow) at an almost unlimited rate if your body/mind is telling you that you are ‘rich’, that you are in the time of plentiful?

There does appear to be a strong correlation between the rise of obesity and consumer debt - but that does not mean the link is causal. But I will in the future start outlining the potential biological link between the brain changes that occur to induce obesity and/or the changes in the brain that occur with obesity that could influence economic choices.

Scary potential future ? Yes.

Can you hack your body/mind to make better economic choices?

Jul 15

The ancient Greeks (Aristotle) considered the heart the center of our thinking. While over the last 2,000 years we have altered our view, and now know the brain is our control center (for most of us), we can still get a window into our brain from listening to our heart.

I previously covered some simple measurements we can use to track our overall health, and then went into details about heart rate measurements to get insights into your health.

Review of the general background:

Heart rate is controlled by the autonomic nervous system (ANS). There are two main branches of the ANS: the sympathetic system which is involved in energy mobilization (think increased HR), and parasympathetic system acting as the opposite and hence restoration (decreased HR). When the system is nice and healthy there is an appropriate balance between these two controllers and your HR changes according to the appropriate response to the current situation. A perfect example of this is when you exercise your HR increases to meet the demand of the higher energy requirements. In contrast, in an ‘unhealthy’ system one of the two branches of the ANS can come to dominate which leads to various diseases, or accelerate certain diseases, with the most prominent being cardiovascular disease (CVD). Typically the unbalance occurs with an overactive sympathetic and/or underactive parasympathetic.

Normally, the HR is tonically inhibited by the parasympathetic component of the ANS and is mainly mediated by the vagal nerve innervation of the heart. So resting HR can be considered a measurement of the parasympathetic system.

But the topic today is what can the heart tell us about the brain.

So the first question would be how does the brain actually influence the heart? Well, one anatomical pathway starts in your frontal lobe, which in general inhibits the amygdala (part of the limbic system). One of the amygdala functions is to automatically mediate defensive behavior (fight or flight). Hence, the frontal cortex via direct and indirect pathways (including the amygdala) of the parasympathetic system has an inhibitory effect on heart rate (and other measurements of the balance between parasympathetic and sympathetic systems). This could be how various people can control their heart rate by mediation and other techniques.

Now what would you guess occurs when people face conditions of uncertainty or threat? The activity level of the frontal cortex is reduced - thereby releasing its normal inhibitory activity on the amygdala/limbic system and other parasympathetic pathways and your hear rate increases. Along with heart rate increase comes changes in other measurements of the balance between parasympathetic and sympathetic systems - hence your HR variability (HRV) decreases.

Interestingly, various altered brain states such as depression, anxiety, schizophrenia, and post-traumatic stress disorder (PTSD) are associated with reduced frontal cortex activity (hypoactivity) (Thayer and Lane 2007). Now these same people have poor executive function and memory, which is consistent with reduced frontal cortex activity, but also do not adapt well to novel neutral stimuli, and are more prone to think something is a threat (when it is not). The question then does these same mental health conditions also result in altered HR measurements? Lowered heart rate variability (HRV) has been linked to anxiety, panic disorder, depression, and schizophrenia (Mujica-Parodi et al., 2007). For a quick primer of HRV see this piece.

HRV background:

Heart rate variability can be broken into time and frequency. Regarding time, though there are still many measurements of this, you can think of one as the standard deviation between interbeat intervals (IBI). As for frequency: both low frequency and high frequency spectral power have been used an indices of vagal activity.

Another way to look at these two measurement of variability is that frequency domains are an attempt to try to dissect out the excitatory (sympathetic) and inhibitory (parasympathetic) components/contributions, while the time series measurements are seeking to measure the overall chaos or complexity in the system.

As for the general take home message, people with a higher rate of variability are considered healthier and less likely to die. So at first this might sound somewhat counterintuitive for those not familiar to the heart field or chaos theory. But think of it as the more dynamic the system the better it can react to external changes.

Anxiety and HRV.

But is there really a link between the limbic activity of the amygdala and heart rate measurements? Mujica-Parodi et. al., 2007 examined the link between anxiety, heart rate variability, and limbic dysregulation. The researchers showed happy, neutral, and fearful faces while measuring their heart and scanning (fMRI) their brains. They used time ratio heart rate variability (HRV) - with high HRV reflecting a greater degree of chaos and a system with a greater capacity for adaptation to changing environmental condition (in this case a good thing - see my previous article). Overall, they found the subjects with the highest anxiety displayed the most limbic dysregulations - e.g. heightened and longer activation of the limbic system to neutral faces. Additionally, the higher the limbic dysregulation (e.g. left amygdala) there was an increase in the sympathetic activation and the lower the chaos in the heart-rate (lower HRV).  The authors go on to argue/explain that a healthy mind is able to quickly react to changing excitatory (sympathetic) environmental conditions with equally strong and quick inhibitory activity via the parasympathetic to head back toward homeostasis. If the inhibitory parasympatheic system is slow and/or non responsive to the outside threats then the sympathetic drive dominates, which results in lower HRV (because once elevated the heart rate tends to stay there). Now from this paper I did not think we could know where the problems originates. However, the author argues that the limbic dysregulation is their best educated guess, based on their results. But I would think if the frontal lobe is not functioning correctly then you would also not get the appropriate response of the limbic system, feel high anxiety, and have altered heart rate readings. And remember many of the mental diseases mention earlier including anxiety is related to hypoactive frontal lobe. Take home: higher anxiety is associated with reduced HRV and greater sympathetic drive.

Pain and HRV.

Could pain threshold and HRV be related? Applehans and Luecken 2008 found that people that had greater low-frequencey (LF)  HRV had a lower rating of pain to 4 degree water (cold) - a higher threshold of pain. However, high-frequency (HF) HRV was not associated with pain ratings. Why did LF but not HF variability correlated to pain threshold? According to the authors argument LF plays a role in blood pressure by affecting arterial baroreflex and interestingly the baroreflex mediates pain inhibitory pathways during conditions of high negative affective arousal (e.g conditions that cause large drop in blood pressure). Whatever the mechanism, we can see how your current natural setting of your autonomic nervous system, which in this case most appropriate measurement is LF heart rate variability is correlated with your pain threshold.

Heart rate and ability to handle major life stresses.

If heart rate measurements can be related to handling specific pain what about general resilience to life situations? Oldehinkle et al., 2008 examined this question and used simple heart-rate (reflects a balance between sympathetic and parasympathetic) and respiratory sinus arrhythmia (RSA: measures magnitude of rhythmic fluctuations, which is said to be mainly influenced by parasympathetic) . What they found was those subjects with a low resting HR were better able to handle major life stressors than the subjects with normal or high resting HR. The normal/high HR subjects suffered more mental health problems per same unit of major life stress. The researchers found no relationships with the RSA measurement (parasympathetic driven measurement). They conclude that the parasympathetic system was not playing a major role in the relationship they observed since RSA did not correlated with the ability to handle stress, but low HR did. Hence, they suggest that a low sympathetic system is the important variable.

To take this to a more general psychology theory - the stimulation-seeking theory suggests that people with low arousal state feel ‘unpleasant’ and therefore seek out arousing activity to put them into a more ‘balanced state’ for them.  Research cited in the above paper point out that people with low HR prefer high intensity activities along with greater novelty. Interesting to me would be the chicken or egg problem of does a person who does seek out novel and high intensity activity (e.g. looks of physical activity) result in low HR, or is it vice-versa ? Therefore, when life becomes hectic and uncertain (high stress) this might be the preferred situation by the people with a naturally low HR, since it can be considered their desired state for appropriate level of arousal and/or it does not put them over the red line of excessive stress. While those with normal or high HR that encounter the same high stress conditions it might put them above the red line, which eventually leads to mental health issues.

One very interesting line of research would be does exercise which lowers your resting HR make you more resilient to life stresses?

Interestingly, training has been shown to result in a large increase in total power (LF + HF) and even great increase in LF, but only a moderate increase in HF (Gamelin et al., 2007). Along with the well known affect of exercise on lowering resting HR it could be suggested that exercise would increase your pain threshold and make you more resilient to life stresses.

You the reader might say well you already knew all that - of course exercise makes you have a higher pain theshold, we have all experienced that with exercise - you can push harder up the hill after a few months of running, and that exercise is well known to reduce stress. And if you the reader are thinking this I would agree with you, in many cases we already know manyy of the answers, and what we should be doing for our health. However, maybe now we have more objective readings of these improvements by examining various HR measurements.

More so, looking at research like this give us additional reasons/motives to do what we already know we should be doing. This is a very interesting topic that I find constantly popping up - we know what we should be doing for our health (backed by 100s of papers and all the logic and mechanisms) but we still struggle with doing what we know is good for us.

Our heart rate measurements can give us a glimpse into at least parts of our brain function and a way to track changes as we work to improve the health of our brain.

The above is just a working draft of my thoughts - please feel free to send me your thoughts and knowledge on this subject.

To better mental and physical health.

Jun 19

On a lighter note today - can viewing attractive public personalities be good for your brain?

Brad and Angelina can serve as examples for this blog piece to appeal to both sexes.

Matsunaga et al., 2008) viewing a person you judge as attractive (a favorite person) causes an increase in circulating natural killer cells (better immune system) and the peripheral dopamine levels, along with elevation in positive emotions. Additionally, there was greater activation of the medial prefrontal cortex, thalamus, hypothalamus, subcallosal gyrus, posterior cingulate cortex, superior temporal gyrus, and cerebellum versus the control condition.

To make this more clear, two videos were watched on different occasions: 1) a 4 minute video of someone the individual participant consider to be a favorite (attractive) personality (famous actresses in this study), 2) a 4 minute video of a newscaster the individual participants did not consider attractive, reporting the weather. The various blood components and brain scans were obtained under these two conditions and compared.

Presto - seeing someone attractive increased activation in numerous brain areas, and there was an increase in the immune system and peripheral dopamine levels.

Another hack for the brain brought to your friendly neuroscientist.

Who are you going to look at today to improve your health?


(idea via Neurocritic)

May 29

What are some of the baby steps we can all take to increase our brain health? I have told you that simple exercise and exposing yourself to new things (enriched environment) will improve your brain health in numerous ways. However, too many of us balk at implanting either of these because we do not think we have the time and energy to make the big commitment required to get results.

We get stuck into the thinking that big changes both in size and volume are required to produce meaningful changes. But you need to consider that anything is better than nothing. The research out there supports this idea that small steps can make a difference.

Sure it is most likely that 45 minutes of day of aerobic exercise might be the optimum level of exercise (at least most bang for the buck) but other research shows benefits with just 12 minutes a day of exercise. 12 measly minutes – we all have that to spare. Take a slightly longer walk to the bus, from the bus, go up and down several flights of stairs. I have personally found that stair walking is a very simple and efficient way of building fitness. Don’t take the elevator – walk the stairs.A Calgary Stampeders player climbing the stairs at McMahon Stadium during 2007 training camp.

Image via Wikipedia

The next trick is to put in a few extra trip up a set of stairs that are not required in your day to day life – do it for the sheer fun of it (plus the health benefits). I have seen so many people at university where I work punch the elevator button to go up one floor – yes one floor. All ages including 18-22 year old undergraduates. It takes them longer to get where they are going by the time the slow elevators transport them than if they just went up the stairs which are ten steps away from the elevator. Therefore, don’t worry about going to the optimal level just start with something.

Here are a few links regarding stair climbing workout and benefits.







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