(These are all of the posts we have on this topic)
1st Post on Stress and Depression Why the Current Theory Fails So Often
2nd Post on Stress and Depression Cortisol
3rd Post on Stress and Depression Pregnenolone
5th Post on Stress and Depression BDNF
6th Post on Stress and Depression: The Cholesterol/Dopamine Connection
7th Post on Stress and Depression: Increasing levels of Brain Derived Neurotrophic Factor (BDNF)
6th Post on Stress and Depression: The Cholesterol/Dopamine Connection
7th Post on Stress and Depression: Increasing levels of Brain Derived Neurotrophic Factor (BDNF)
Hello again and welcome to our 7th post on the biology of stress and
depression. In this post we will be discussing what types of exercise have been
shown to increase levels of Brain Derived Neurotrophic Factor (BDNF). As stated
in a previous post (click here to go to the post), BDNF is like fertilizer for
your brain's neural circuits. If you want to learn something new, you need BDNF
to help you pave those new neuro-pathways. These pathways can control something
physical like how to throw a perfect spiral with a football, or something
psychological like a new mindset or attitude. Either way you need to grow new
circuits for your nerves in order to wire yourself for a new task. This process
of creating these neurological structures or networks to adapt to new
psychological, physiological, or emotional needs is called
neuroplasticity.
In his book, Evolve Your Brain, Dr. Joe Dispenza eloquently described the
neural network as, ".literally millions of neurons firing together in diverse
compartments, modules, sections, and subregions throughout the entire brain.
They team up to form communities of nerve cells that act in unison as a group,
clustered together in relation to a particular concept, idea, memory, skill, or
habit. Whole patterns of neurons throughout the brain become connected through
the process of learning, to produce a unique level of mind."
So the term "neural network" describes a unique arrangement of connections
of neurons that fire in a specified sequence. These networks allow you to
perform tasks like tapping your feet, or recalling the lyrics to your favorite
song as well as "learning" new tasks as required. Neuroplasticity is the ability
of the brain to adapt and change. This flexibility in our nervous systems is
based on the modification of existing neural networks and the creation of new
ones. A key player in our ability to adapt to new nerve stimulus is a steady
supply of BDNF.
If can keep optimal levels of BDNF ready to feed and develop new circuits
in your brain the process of developing new skills, knowledge, and attitudes
becomes much easier. So, BDNF helps you be the "you" that you want. You build
yourself from the inside out firing and re-wiring new pathways based on what you
choose to focus on. The implication here is that each of us an unexpected degree
of control over who we are and how we feel.
The previous post on the stress hormone cortisol discussed the inverse
relationship with cortisol has with cortisol production. If stress hormone and
cortisol levels go up levels of BDNF go down. Cortisol also decreases the body's
ability to deal with stress. It does this though damaging the hippocampus, a
major contributor in the body[s ability to adapt to stress. As a result we feel
stress more acutely even as the body has become even less able to cope! It's a
really strong feedback loop that encourages us all to be stressed. The good news
is this nasty little equation can be reversed. By increasing BDNF we can
decrease damaging levels of cortisol. This is how you re-wire to the new you
that you want to be.
Our first look at increasing BDNF is exercise.
While our muscles pump iron, our cells pump out something else: particles
that nourish a strong brain. For years scientists have struggled to explain the
well-known mental benefits of exercise. These benefits include a variety of
paybacks, including: offsetting depression and aging, to fighting Alzheimer's
and Parkinson's disease. And, a team of researchers may have finally discovered
a solid molecular link between how a good workout promotes a healthy
brain.
Muscle cells increase the production of a protein called FNDC5 while you
are exercising. A portion of this protein, called irisin, gets cut off and
released into the bloodstream. Spiegelman and his colleagues at Harvard Medical
School suspected that FNDC5, and the irisin created from it, are responsible for
exercise-induced benefits to the brain. In particular they were interested, (as
are we!), in increased levels of BDNF.
To sort out how exercise relates to BDNF, Spiegelman and his colleagues
performed a series of experiments in living mice and cultured mouse brain cells.
They put an experimental group of mice on a 30-day endurance training regimen.
They didn't have to coerce their subjects, because running is part of a mouse's
natural foraging behavior. The mice with access to a running wheel ran the
equivalent of a 5K every night. Next, they compared them to a group of mice who
lived like couch potatoes.
Aside from physical differences between wheel-trained mice and sedentary
ones, (not surprisingly, the sedentary group had more body fat), the groups also
showed significant neurological differences. The runners had more FNDC5 in their
hippocampus, an area of the brain responsible for learning and memory. A happy
hippocampus is also associated with better stress management and less depressed
states.
Using mouse brain cells developing in a cell culture, the group next showed
that increasing the levels of the co-activator PGC-1α boosts FNDC5 production,
which in turn drives BDNF genes to produce more of the vital neuron-forming BDNF
protein. They report these results in the journal Cell Metabolism. Spiegelman
says it was surprising to find that the molecular process in neurons mirrors
what happens in muscles as we exercise. The processes parallel each other! The
mind and body are not separate after all.
How is the brain getting the signal to make BDNF? Some have theorized that
neural activity during exercise (as we coordinate our body movements, for
example) accounts for changes in the brain. But it's also possible that factors
outside the brain, like those proteins secreted from muscle cells, are the
driving force. To test whether irisin created elsewhere in the body can still
drive BDNF production in the brain, the group injected a virus into the mouse's
bloodstream that causes the liver to produce and secrete elevated levels of
irisin. They saw the same effect as in exercise: increased BDNF levels in the
hippocampus. This suggests that irisin could be capable of passing the
blood-brain barrier, or that it regulates some other (unknown) molecule that
crosses into the brain. This research finally sheds light on how exercise
relates to BDNF and other so-called neurotrophins that keep the brain strong and
healthy.
We have come a long way in the past twenty-five years in our understanding
of the brain, from a generally accepted perception of the brain as being a
hardwired, fixed and immutable organ to one that celebrates its dynamism. Now
get out there and move it!
