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Stress and Neural Wreckage: Part of the Brain Plasticity Puzzle

Victoria Crater MarsEditor’s Note: Below you have a very insight­ful arti­cle on stress by Gre­gory Kel­let, a researcher at UCSF. Enjoy!


My brain is fried, toast, fraz­zled, burnt out. How many times have you said or heard one ver­sion or another of these state­ments. Most of us think we are being fig­u­ra­tive when we utter such phrases, but research shows that the bio­log­i­cal con­se­quences of sus­tained high lev­els of stress may have us being more accu­rate than we would like to think.

Crash Course on Stress

Our bod­ies are a com­plex bal­anc­ing act between sys­tems work­ing full time to keep us alive and well. This bal­anc­ing act is con­stantly adapt­ing to the myr­iad of changes occur­ring every sec­ond within our­selves and our envi­ron­ments. When it gets dark our pupils dilate, when we get hot we sweat, when we smell food we sali­vate, and so forth. This con­stant bal­anc­ing act main­tains a range of sta­bil­ity in the body via change; and is often referred to as allosta­sis. Any change which threat­ens this bal­ance can be referred to as allo­sta­tic load or stress.

Allo­sta­tic load/stress is part of being alive. For exam­ple just by get­ting up in the morn­ing, we all expe­ri­ence a very impor­tant need to increase our heart rate and blood pres­sure in order to feed our newly ele­vated brain. Although usu­ally man­age­able, this is a change which the body needs to adapt to and, by our def­i­n­i­tion, a stressor.

Stress is only a prob­lem when this allo­sta­tic load becomes over­load. When change is exces­sive or our abil­ity to adapt is com­pro­mised, things start to go wrong. We will focus here on what seems to be hap­pen­ing in the brain under such conditions.

Energy Mobi­liza­tion

Whether it’s get­ting up in the morn­ing, wor­ry­ing about the non-existent past/future, or get­ting angry at your last park­ing ticket, stress takes energy. One of the major roles of the infa­mous fight or flight response is to mobi­lize energy, and it does this well. If you need to run away from a swarm of killer bees or fend off an attack­ing bear, you will be assisted by var­i­ous chem­i­cals pro­duced within the body. These include the well-known adrenaline–now more com­monly referred to as epinephrine–and a lesser known group of chem­i­cals known as the glu­co­cor­ti­coids, most notably cor­ti­sol. Both epi­neph­rine and the glu­co­cor­ti­coids are involved in mak­ing stored energy avail­able for use in the form of fats and sug­ars. Epi­neph­rine does so over the short term (within sec­onds) while glu­co­cor­ti­coids act over a longer period (min­utes to hours). Let’s look at the effects of the later of the two, the glucocorticoids.

Your Brain on Stress

Cor­ti­sol, the most promi­nent of the glu­co­cor­ti­coids, does an excel­lent job of allow­ing us to adapt to most stres­sors which last more than a cou­ple of min­utes but under an hour. Short term it will actu­ally enhance our immune sys­tem, mem­ory and atten­tion. Long term, past ½ hour to an hour, exces­sively ele­vated cor­ti­sol lev­els start to have detri­men­tal effects. It seems we were designed more to deal with short spurts of high stress, such as beat­ing back that attack­ing bear, rather than long drawn-out stres­sors such as meet­ing deadlines.

Our brains appear to be most vul­ner­a­ble to the effects of exces­sive stress in a region called the hip­pocam­pus. The hip­pocam­pus is a mass of neu­rons each with mul­ti­ple branch-like exten­sions (den­drites and axons) which make con­nec­tions (synapses) with other neu­rons all across the brain. Among other things, this region is impor­tant in deal­ing with emo­tions and con­sol­i­dat­ing new mem­o­ries. As with all brain regions, its abil­ity to adapt relies upon being able to alter the branch­ing and con­nec­tions of its neu­rons. The hip­pocam­pus is also one of the only regions of the brain known to be able to pro­duce new neu­rons, a process called neurogenesis.

Brain Dam­age

Endur­ing a high stres­sor for more than 30 min­utes to an hour has been shown to neg­a­tively impact the hip­pocam­pus in var­i­ous ways. To begin, sus­tained expo­sure to higher than nor­mal lev­els of cor­ti­sol results in the prun­ing back of the num­ber of branches and synap­tic con­nec­tions of hip­pocam­pal neu­rons. By a vari­ety of mech­a­nisms, these con­di­tions also increase the rate of cell death in this region of the brain.

As if this wasn’t bad enough, recent research is also demon­strat­ing that sus­tained increases in glu­co­cor­ti­coid lev­els also has neg­a­tive effects, impair­ing the hippocampus’s abil­ity to cre­ate new neurons.

Over a period of time, all of this results in the shrink­ing in size of the hip­pocam­pus with asso­ci­ated declines in cog­ni­tive func­tion, includ­ing the abil­ity to retain new infor­ma­tion and adapt to novel situations.

Dam­age Control

For­tu­nately the neg­a­tive effects of exces­sive stress can not only be stopped but also reversed once the source (psy­cho­log­i­cal or phys­i­cal) is removed or suf­fi­ciently reduced. Next time we will explore tech­niques one can use to pro­tect our brains by man­ag­ing the unavoid­able stres­sors we all face as part of being human.

Gregory Kellet on stress management— Gre­gory Kel­lett has a mas­ters in Cog­ni­tive Neurology/Research Psy­chol­ogy from SFSU and is a researcher at UCSF where he cur­rently inves­ti­gates the psy­chophys­i­ol­ogy of social stress.


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11 Responses

  1. Gigi Aelbers says:

    Great arti­cle. Reads well and is very clear, even if you’re not a sci­ence major.

  2. Alvaro says:

    Hello Gigi, glad you enjoyed it. I do think Gre­gory did an amaz­ing job at explain­ing such a com­plex topic.

  3. Michelle B says:

    Excel­lent article–especially appre­ci­ated the con­nec­tion made between stress and using of energy via par­tic­u­lar hor­mones which if remain ele­vated exert neg­a­tive effects on a spe­cific brain region.

  4. Gregory says:

    Thanks for the kudos,

    Yeah I find it intrigu­ing that we are actu­ally designed to han­dle most acute stres­sors quite well,…if not the exces­sive, longterm variety.

  5. mig says:

    the best part of this is that if we make a change now in the way we han­dle our stress the neg­a­tive effects can be reversed. Cool. I’m going to go chill out now.

  6. Alvaro says:

    hello Mig, it is not clear if every­thing can be fully “reversed”, but as Gre­gory points out there is much we can do today, tomor­row, next week…to help main­tain our brains.

  7. HealthBlawg says:

    Grand Rounds Vol. 4 No. 21: The Valentine’s Day Edition…

    Happy Valentine’s Day (almost), and wel­come to Grand Rounds, the weekly rotat­ing car­ni­val of the best of the med­ical blo­gos­phere, hosted improb­a­bly this week by — hor­rors! — a health care lawyer and con­sul­tant. I’ve orga­nized this edi­tion around th…

  8. Pat says:

    Great arti­cle. I lost all my beau­ti­ful thick long hair about 20 years ago, all due to stress. I do every­thing I can do now dur­ing stress­ful times to eat right, take vit­a­mins, and get plenty of exer­cise. (Blog­ging helps me too!)

  9. ron mack says:

    This is a fan­tas­tic arti­cle that goes a long way in help­ing me to real­ize why I have been for­get­ting things so often! Valuable!

  10. Being in my mid 80’s I am very con­scious of memory/nonmemory. This arti­cle gives me some insight in improv­ing the for­mer and reduc­ing the latter.

  11. Rajni says:

    I have seen clearly the neg­a­tive effects of stress on mem­ory, deci­sion mak­ing and act­ing ratio­nally. Your descrip­tion of neu­ro­ge­n­e­sis and how it gets effected by long term stress explains it all very clearly.

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