Physical exercise: why aerobic exercise enhances neurogenesis and neuroplasticity

jAs lit­tle as three hours a week of brisk walk­ing has been shown to halt, and even reverse, the brain atro­phy (shrink­age) that starts in a per­son­’s for­ties, espe­cial­ly in the regions respon­si­ble for mem­o­ry and high­er cog­ni­tion. Exer­cise increas­es the brain’s vol­ume of gray mat­ter (actu­al neu­rons) and white mat­ter (con­nec­tions between neurons).

Through increased blood flow to the brain, phys­i­cal exer­cise trig­gers bio­chem­i­cal changes that spur neu­ro­plas­tic­i­ty – the pro­duc­tion of new con­nec­tions between neu­rons and even of neu­rons them­selves. Brain exer­cise then pro­tects these fledg­ling neu­rons by bathing them in a nerve growth fac­tor and form­ing func­tion­al con­nec­tions with neigh­bor­ing neu­rons. Dr. Gage’s work of the Salk Insti­tute for Bio­log­i­cal Stud­ies, have shown that exer­cise helps gen­er­ate new brain cells, even in the aging brain.

Study­ing this top­ic, Dr. Smeyne of the Saint Jude Chil­dren’s Research Hos­pi­tal in Mem­phis, found that results could be seen in two months in Parkin­son patients. Parkin­son patients demon­strate a pro­gres­sive loss of dopamine neu­rons in the sub­stan­tia nigra pars. After two months of exer­cise, the patients had more brain cells. High­er lev­els of exer­cise were shown to be sig­nif­i­cant­ly more ben­e­fi­cial than low­er amounts, although any exer­cise was bet­ter than none. Smeyne also found that start­ing an exer­cise pro­gram ear­ly in life was an effec­tive way to low­er the risk of devel­op­ing Parkin­son’s dis­ease lat­er in life.

Numer­ous ani­mal stud­ies have shown that phys­i­cal exer­cise has a mul­ti­tude of effects on the brain beyond neu­ro­ge­n­e­sis, includ­ing increas­es in var­i­ous neu­ro­trans­mit­ters and nerve growth fac­tor lev­els, and angio­gen­e­sis (the for­ma­tion of new blood vessels).

In 2003, Dr. Col­combe and Kramer, ana­lyzed the results of 18 sci­en­tif­ic stud­ies pub­lished between 2000 and 2001. The results of this meta-analy­sis clear­ly showed that phys­i­cal fit­ness train­ing increas­es cog­ni­tive per­for­mance in healthy adults between the ages of 55 and 80.

Anoth­er meta-analy­sis pub­lished in 2004 by Dr. Heyn and col­leagues shows sim­i­lar ben­e­fi­cial effects of fit­ness train­ing for peo­ple over 65 years old who had cog­ni­tive impair­ment or dementia.

What type of exer­cis­es is needed?

Accord­ing to Dr. Art Kramer, aer­o­bic exer­cise, at least thir­ty to six­ty min­utes per day, three days a week, has been shown to have a pos­i­tive impact on brain func­tions. Impor­tant­ly, the exer­cise does not have to be stren­u­ous, walk­ing have been shown to have pos­i­tive effects too.

Keep learn­ing by read­ing more arti­cles in the Resources sec­tion, and also please con­sid­er join­ing our free month­ly Brain Fit­ness eNewsletter

This new online resource is based on the con­tent from the book The Sharp­Brains Guide to Brain Fit­ness (May 2009, $19.95), by Alvaro Fer­nan­dez and Dr. Elkhonon Goldberg.

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