I apologize for the long delay in getting back to this column but I have a good excuse. We just recently had a baby, and boy, that takes care right there of the physical exercise need. Between carrying the baby upstairs and downstairs, running to get the baby, getting out of the bed and picking the baby up and putting the baby down a couple of times a night no you need not worry about getting your daily exercise dose in…Now, the majority of the answers to my post on the brain virtues of physical exercise suggests that most people think that the brain benefits of physical exercise are mostly to be understood as complementary effects of a healthy life style.
Is this correct? In my post today I will attempt to answer this question.
First, while generally healthier people seem to have healthier brains, the physical exercise effect on the brain seems to be independent of other things. One of the most important development in neuroscience was when the official dogma claiming that there was no neurogenesis (production of new brain cells) in the adult brain was toppled. Now we know that the brain is “plastic†meaning that, under the right circumstances, the brain can change in terms of both producing new cells and getting more cells connected to each other.
One of the places where neurogenesis has been shown to occur in the adult brain is the dentate gyrus, a strip of grey matter placed deep down in the brain. The dentate gyrus is a part of the hippocampus, the main memory structure, and has been shown to play a role in the forming of new memories. What can the dentate gyrus teach us with regards to physical exercise?
Following a series of extremely thought provoking experiments researchers from the Gage laboratory at UCSD concluded that exercise leads to the production of new brain cells in the dentate. First the researchers found that mice housed in an enriched environment (a larger cage with toys, tunnels, and more opportunity for physical activity, learning, and social interaction than in standard bare cage) have an increased number of new neurons in the dentate gyrus.
The enriched environment is a mice equivalent of not only healthy but good living: leisurely enjoying life, getting both physical and intellectual stimulation, socializing with friends. Now, the fact that new neurons were produced was a big enough news in itself but the Gage group did not stop there. Their next goal was to figure out if neurogenesis was the result of a sum of factors acting together (i.e. the enriched environment) versus a specific effect of individual factor. So, they first dissected the enriched environment in a number of “sub†environments. In their next experiment they placed the mice in a “learning environment†where they had access to a maze, a “physical exercise environment†where mice had unlimited access to a running wheel, in addition to enriched and standard (empty cage) environments. Then they compared the groups in terms of behavioral performance and eventually looked at their brains.
Their conclusion was anything but expected: while both enrichment and wheel running led to improved spatial memory function only physical exercise in a running wheel also promoted neurogenesis and enhanced the survival of newborn neurons in the dentate gyrus.
Bottom line: exercising seems to literally mean “exercising the brainâ€Â.
So, in lieu of conclusion, till next I wish you all happy trails (and I don’t mean it as just trails on the paper in a paper and pencil memory task)!
Adrian Preda, M.D. is an Associate Professor of Psychiatry and Human Behavior in the UC Irvine School of Medicine’s Department of Psychiatry and Human Behavior. His expertise in human behavior, psychology and spirituality is based on years of experience working as a psychiatrist, psychotherapist, teacher and researcher in a variety of academic clinical and non-clinical settings. He also teaches the UC Irvine Extension class The Mind that Changes the Brain: Wellness in the Second Millennium.
References:
van Praag H, Christie BR, Sejnowski TJ, Gage FH (1999) Running enhances neurogenesis, learning, and long-term potentiation in mice. Proc Natl Acad Sci USA 96: 13427–13431
van Praag H, Kempermann G, Gage FH (1999) Running increases cell proliferation and neurogenesis in the adult mouse dentate gyrus. Nat Neurosci 2: 266–270.
Farmer J, Zhao X, van Praag H, Wodtke K, Gage FH, Christie BR (2004) Effects of voluntary exercise on synaptic plasticity and gene expression in the dentate gyrus of adult male Sprague-Dawley rats in vivo. Neuroscience 124: 71–79
Related reading:
Dr. Andrew Newberg and I, at the University of Pennsylvania’s Center for Spirituality and the Mind, heartily concur with Dr. Preda. In fact, in our forthcoming book (How God Changes Your Brain) we cite considerable evidence that aerobic exercise is one of the three best ways to exercise your brain (meditation-which is our field of research-only came in fourth). Brain scans show that vigorous exercise strengthens every part of the brain, and if you’re between the ages of 18 and 90, exercise is going to lengthen your life by about 10%.
Exercise can even be viewed as a form of meditation because it involves sustained concentration and a deliberate regulation of body movements and breathing.
Vigorous stretching, such as yoga, also does wonders for your brain. In a recent meta-analysis of 813 meditation studies, the researchers stated that yoga was as beneficial as exercise. It can even prevent the onslaught of migraine headaches.
In a study conducted in 2007, researchers at the Boston University School of Medicine found that levels of the neurotransmitter GABA increase after a single 60-minute yoga session. Since people who suffer from depression and anxiety disorders have low levels GABA, yoga exercise, as well as other forms of aerobic exercise, is a valid modality for improving psychological and mental health. It even has been found to reduce the symptoms of schizophrenia.
Exercise enhances a wide range of cognitive skills in children and adults.
All forms of exercise enhance neural plasticity and rebuild damaged circuits caused by brain lesions and strokes. Exercise improves cognition and academic performance. It repairs and protects you from the neurological damage caused by stress. It enhances brain plasticity. It boosts immune function. It reduces anxiety. It can be used to treat clinical depression and it is just as effective as antidepressants. In fact, for older patients, exercise is equivalent to twelve sessions of psychodynamic psychotherapy. It slows down the loss of brain tissue as you age, protects you from Alzheimer’s disease, and reduces your vulnerability to chronic illness. Need I say anything more to convince you of the importance of exercise? But don’t take my word for it; check the references I cite below that support the claims made above.
Mark Waldman
Associate Fellow
Center for Spirituality and the Mind
University of Pennsylvania
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Vaynman, S. and F. Gomezâ€ÂPinilla (2005). License to run: Exercise impacts functional plasticity in the intact and injured central nervous system by using neurotrophins. Neurorehabilitation and Neural Repair 19(4): 283–295.
McMorris T, Collard K, Corbett J, Dicks M, Swain JP. A test of the catecholamines hypothesis for an acute exercise-cognition interaction. Pharmacol Biochem Behav. 2008 Mar;89(1):106–15.
Hillman CH, Erickson KI, Kramer AF. Be smart, exercise your heart: exercise effects on brain and cognition. Nat Rev Neurosci. 2008 Jan;9(1):58–65.
Tomporowski, P. D. (2003). Effects of acute bouts of exercise on cognition. Acta Psychologica 112(3): 297–324.
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Cotman CW, Berchtold NC, Christie LA. Exercise builds brain health: key roles of growth factor cascades and inflammation. Trends Neurosci. 2007 Sep;30(9):464–72.
Dishman RK, Berthoud HR, Booth FW, Cotman CW, Edgerton VR, Fleshner MR, Gandevia SC, Gomez-Pinilla F, Greenwood BN, Hillman CH, Kramer AF, Levin BE, Moran TH, Russo-Neustadt AA, Salamone JD, Van Hoomissen JD, Wade CE, York DA, Zigmond MJ. Neurobiology of exercise. Obesity (Silver Spring). 2006 Mar;14(3):345–56.
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When I suffered from depression and got no help from anti depressants, I searched the medical journals to discover that exercise is actually more effective than any antidepressant.
It is the most underrated cure for depression because it is so often scoffed at and needless to say, difficult to be motivated to do.
But, it has by far the better side effects! 🙂
When I begin to feel blue, I lift weights or go for a walk or bike ride.
I am now depression free for 6 years thanks to implementing a regular exercise routine as the first part of my recovery plan and now lifestyle.
Dr. Preda,
Congratulations on your new baby!
I just read your previous post and the comments. While I think any one of the twelve items you mentioned at the end would be interesting, I think the most interesting would be any clarification on the “dosage” of exercise that you allude to and seems to be a main interest of yours already. Specifically, what types of exercise are most effective? High intesity aerobic (i.e. running), low intensity aerobic (i.e. walking), strength, stretching, or perhaps a sport with more varied requirements? What is the minimum required to see a benefit? Is there a plateau? Is there a point when exercise becomes detrimental? While I’m sure you could add to the forum in any number of ways, plenty of people are talking about the many brain benefits of exercise. Far fewer, it seems to me, are talking about the parameters of the exercise itself, and how to best realize those benefits.
Mark, thank you for that excellent context.
Merri, great to hear you are feeling so well now!
Tim: I will let Adrian answer your superb questions, but you probably saw in the Comments to the previous post that the main message here is DON’T BE SEDENTARY, do at least 2–3 weekly sessions of cardio exercise (any intensity).
Thnx for the article. I feel better about my weightlifting training now 🙂
Is there research specific to the role of physical exercise on the ability to be a more effective communicator?
While the evidence you cite for neurogenesis and its association with exercise is certainly interesting and potentially important, it is important to keep in mind that it is not clear whether neurogenesis is indeed the mechanism that underlies improved brain function. I certainly would like neurogenesis to do all of these wonderful things, however, what about the following observations:
1) mice that have inborn predisposition to increased wheel running actually have lower (or no different) levels of neurogenesis than their less active counterparts exposed to running wheels
2) I am aware of only one study that reported differences in neurogenesis in depressed patients. These data were recently presented by the group of Dr. Victoria Arango and Dr. John Mann of Columbia University at the recent Society for Neuroscience meeting. These investigators found lare increases in neurogenesis in depressed individuals treated with antidepressants vs. non-treated depressives and non-depressed controls. Yet, patients in both depressed groups (those on anti-depressants and those not treated) were equivalently depressed.
Clearly these examples indicate that our knowledge about the role of neurogenesis is imperfect. What about alternative mechanisms? Such as changes in serotonergic, noradrenergic, and/or dopaminergic neurotransmission? All of these transmitter systems are impacted by exercise, and all are known to affect mood, affect, and overall brain function.
Ilan,
I agree – exactly how neurogenesis correlates with brain performance is still to be determined. That being said, there is plenty of empirical data coming from the animal litt. showing that increased neurogenesis correlates with improved performance. Also, there is accumulating evidence that a lack of neurogenesis is bad for the brain. For example, patients with depressive disorders or post-traumatic stress disorder have reduced hippocampal volume. Now, while the jury is still out in terms of determining if this is a cause or an effect, the fact is that the hippocampus is the neurogenesis star when it comes to the adult brain. So, while there is no direct evidence linking neurogenesis and performance in humans, the circumstantial evidence is pretty compelling.
Ilan,
Answer to #1:
Can you please indicate the reference? I can only speculate here (please understand that I am really going on a limb without knowing the details of the experiment). Here is a possible interpretation: we might need to reach outside and pick activities that normally lie outside our comfort zone (“inborn predispositionâ€Â) if we are to get maximum brain points. I.e., a runner might get greater brain benefits from spending time in a library, while a library rat might be well served by getting some treadmill time under his belt.
Answer to #2:
What was the time frame of this experiment? How was neurogenesis quantified? It is a known that clinical response lags way behind “objective“ brain changes when it comes to depression. While most antidepressants (ADs) increase the level of neurotransmitters in the synapse days after they are administered, the full clinical response is not seen until 6–8 weeks after treatment initiation.
Hi Susan,
Here are a few of my non-systematic observations. Great communicators can be fit or fat. Also, some very fit people tend to be more comfortable at the gym rather than in a social setting.
Adrian,
Re. #1, check out some of the work by Rhodes JS and colleagues. For instance, INTEGR. COMP. BIOL., 45:438–455 (2005). One of the findings they mention in this review is that mice w. high inborn activity levels increase neurogenesis w. voluntary wheel running, but show impaired learning. I also heard this investigator speak a few years ago at the Experimental Biololgy Meeting where her presented data showing lack of increased neurogenesis in mice w. increased voluntary exercise. Though I have not been able to find these data in print. Maybe no one wants to believe these findings, and they keep getting shot down by reviewers (or maybe they are flawed)? In the paper cited above, the authors raise an intriguing possibility that exercise may actually contribute to neuronal death in hippocampus via increased CORT secretion. Increased neurogenesis then may be a compensatory response.
Re. #2, I don’t remember whether the time fram issue was presented. I presume that the subjects were treated w. ADs for a long time. Usually in such studies brains are collected from patients who have had a long history of mental illness and treatment. I’m sure that these investigators are aware of the lag between treatment initiation and clinical response and would have designed their study accordingly. Re. their methodology, it was sound. They didn’t measure BrdU incorporation, but used Ki-67 and doublecortin immunocytochemistry together with neuronal and glial markers.
In any case, I think that neurogenesis is a very interesting phenomenon in it of itself. It’s very exciting in that it shatters the age-old dogma that the adult brain is not capable of generating new neurons. But whether it is responsible for all of the wonderful effects of exercise, environmental enrichment, anti-depressant medications, improved diet, etc. is not clear (at least not to me). What the field clearly needs is a way to cleanly disrupt neurogenesis (and cell death, and differentiation of glial progenitors into neurons, and their insertion into existing circuits, etc.) to see whether such manipulations affect learning, cognition, depressive- and anxiety- like behaviors, etc.
A lot of this is about self image. If people look good and feel good they are less likely to be depressed.
I have been doing aerobic exercise and walking since comming off tranxene after 30 years dependency I feel that exercise has given me back my life both mentally and physically. my age is 71
Hello Alan — thank you for sharing, and congrats