Given the grow­ing media cov­er­age men­tion­ing the terms Cog­ni­tive Reserve and Brain Reserve, you may be ask­ing your­self, “What exactly is my Cog­ni­tive (or Brain) Reserve?”

The cog­ni­tive reserve hypoth­e­sis, tested in mul­ti­ple stud­ies, states that indi­vid­u­als with more cog­ni­tive reserve can expe­ri­ence more Alzheimer’s dis­ease pathol­ogy in the brain (more plaques and tan­gles) with­out devel­op­ing Alzheimer’s dis­ease symptoms.

How does that work? Sci­en­tists are not sure but two pos­si­bil­i­ties are con­sid­ered.
1. One is that more cog­ni­tive reserve means more brain reserve, that is more neu­rons and con­nec­tions (synapses) between neu­rons. Indi­vid­u­als with more synapses would then have more synapses to lose before the crit­i­cal thresh­old for Alzheimer’s Dis­ease is reached.
2. Another pos­si­bil­ity is that more cog­ni­tive reserve means more com­pen­satory processes. The brain of indi­vid­u­als with more cog­ni­tive reserve would use more alter­na­tive net­works to com­pen­sate for the dam­ages caused by the pathol­ogy in pre­vi­ously used networks.

In a newly pub­lished study, Roe and col­leagues from Wash­ing­ton Uni­ver­sity in St. Louis, used the num­ber of years of edu­ca­tion as a mea­sure of cog­ni­tive reserve. Why years of edu­ca­tion? Because pre­vi­ous stud­ies have shown that peo­ple who have more edu­ca­tion also exhibit a greater resis­tance to Alzheimer’s symp­toms, even while patho­log­i­cal changes are occur­ring in the brain (see Ben­nett el al., 2003 or Roe, Xiong, et al., 2008).

Roe and her col­leagues stud­ied 198 indi­vid­u­als whose mean age was 67. Out of these 198 indi­vid­u­als, 161 were non­de­mented and 37 were diag­nosed with Alzheimer’s Disease.

All the par­tic­i­pants in the study took a 1.5h bat­tery of tests to eval­u­ate their cog­ni­tive func­tion­ing. They also under­went a PiB PET scan. This brain-imaging tech­nique uses a marker called car­bon 11-labeled Pitts­burgh Com­pound B (PiB). The marker binds to beta-amyloid plaques in the brain and can be seen on a positron emis­sion tomog­ra­phy (PET) scan.

Sta­tis­ti­cal tests were used to assess how the num­ber of plaques in the brain, clin­i­cal and behav­ioral mea­sures, and cog­ni­tive reserve interacted.For par­tic­i­pants who had a large amount of plaques in the brain, per­for­mance on sev­eral cog­ni­tive tests increased with increas­ing edu­ca­tion. This rela­tion­ship was not observed for indi­vid­u­als with a lower amount of plaques in the brain.

These cog­ni­tive tests included the Mini Men­tal State exam­i­na­tion, the Short Blessed test and the Clin­i­cal Demen­tia scale, which are all used to diag­nose demen­tia. What does that mean? This means that indi­vid­u­als with greater edu­ca­tion main­tain bet­ter cog­ni­tive func­tion­ing in the pres­ence of Alzheimer’s Dis­ease pathol­ogy. This new study con­firms the idea that cog­ni­tive reserve (here mea­sured in terms of years of edu­ca­tion) influ­ences the rela­tion­ship between cog­ni­tive func­tion­ing and amount of Alzheimer’s pathology.

It also raises sev­eral questions:

– How many years of edu­ca­tion does one need to be “protected”?

In the stud­ies pub­lished so far indi­vid­u­als with high lev­els of edu­ca­tion were indi­vid­u­als who had 15 years or more of edu­ca­tion. Lit­tle is known about the effect of lower lev­els of education.

–Are years of edu­ca­tion the only mea­sure of cog­ni­tive reserve?

No. Other indi­ca­tors include a chal­leng­ing occu­pa­tion, engag­ing hob­bies and active social net­works. As you can guess, years of edu­ca­tion are eas­ier to objec­tively mea­sure, which may explain why they are used more often in stud­ies of cog­ni­tive reserve.

– Does it mean that if one doesn’t have a high edu­ca­tion level, it is too late, there is noth­ing that one can do?

No! As described above, cog­ni­tive reserve can be mea­sured in other ways. This means that peo­ple who are not highly edu­cated but live a stim­u­lat­ing life and are active socially can still get some neuroprotection.

Ref­er­ences

- Ben­nett, D. D., Wil­son, R. S., Schnei­der, J. A. et al. (2003). Edu­ca­tion mod­i­fies the rela­tion of AD pathol­ogy to level of cog­ni­tive func­tion in older per­sons. Neu­rol­ogy, 60, 1909–1915.
– Roe, C. M., Mintun, M. A., D’Angelo, G., Xiong, C., Grant, E. A., & Mor­ris, J. C. (2008). Alzheimer Dis­ease and cog­ni­tive reserve. Archives of Neu­rol­ogy, 65, 1467–1471.
– Roe, C. M., Xiong, C., Miller, J. P., Caims, N. J., & Mor­ris, J. C. (2008). Inter­ac­tion of neu­ritic plaques and edu­ca­tion pre­dicts demen­tia. Alzheimer Dis. Assoc. Dis­ord., 22, 188–193.

— This arti­cle was writ­ten by Pas­cale Mich­e­lon, Ph. D., for Sharp­Brains. Dr. Mich­e­lon has a Ph.D. in Cog­ni­tive Psy­chol­ogy and has worked as a Research Sci­en­tist at Wash­ing­ton Uni­ver­sity in Saint Louis, in the Psy­chol­ogy Depart­ment. She con­ducted sev­eral research projects to under­stand how the brain makes use of visual infor­ma­tion and mem­o­rizes facts. She is now an Adjunct Fac­ulty at Wash­ing­ton Uni­ver­sity, and teaches Mem­ory Work­shops in numer­ous retire­ment com­mu­ni­ties in the St Louis area.

A few related articles:

- Build Your Cog­ni­tive Reserve– Inter­view with Yaakov Stern

- Phys­i­cal Exer­cise and Brain Health

- Social Con­nec­tions for Cog­ni­tive Fitness