Can cinnamon prevent Alzheimer’s Disease?

You may have come across sev­er­al head­lines like this over the last few weeks, based on a new study appar­ent­ly show­ing that the com­pound that caus­es that bright cin­na­mon smell may help pre­vent the devel­op­ment of tau pro­tein tan­gles, the tan­gles that noto­ri­ous­ly form in brains affect­ed by Alzheimer’s Disease.

Are we to con­clude that cin­na­mon can play a sig­nif­i­cant role in fight­ing Alzheimer’s dis­ease? That per­haps it can match or even sur­pass the ben­e­fits of phys­i­cal and men­tal exer­cise, and oth­er lifestyle factors?

Prob­a­bly not. Let’s see why, by ana­lyz­ing the study in detail.

The Study

In an in vit­ro exper­i­ment (done in a test tube, not in a human or ani­mal) researchers exam­ined the effect of two cin­na­mon com­pounds on tau pro­tein accu­mu­la­tion: cin­namalde­hyde (CA) and epi­cat­e­chin (EC).

Under nor­mal cir­cum­stances tau pro­tein is respon­si­ble for the assem­bly of “micro­tubules” in brain cells. These micro­tubules form the “skele­ton” of the cells. If the pro­tein does not bind prop­er­ly to the micro­tubule it tends to clump togeth­er. This is how tan­gles are formed. And this is impor­tant because these are insol­u­ble fibers that will pre­vent neu­rons from func­tion­ing well.

The study showed that the cin­na­mon com­pound CA was effec­tive in pre­vent­ing the for­ma­tion of tau tan­gles. CA, an oil, seems to inhib­it accu­mu­la­tion by pro­tect­ing the pro­tein from oxida­tive stress. This is because CA binds to cys­teine residues that may oth­er­wise dam­age tau.

The oth­er cin­na­mon com­pound, EC, is a pow­er­ful antiox­i­dant. It can be found in oth­er food, such as blue­ber­ry and choco­late. It not only damp­ens the dam­ages caused by oxi­da­tion but can also inter­act with cys­teine residues in a way sim­i­lar to the pro­tec­tive action of CA.

The Inter­pre­ta­tion

Can one con­clude from this study that ingest­ing large amounts of cin­na­mon could pro­tect from devel­op­ing Alzheimer’s?

The answer is no. This was a “test tube” exper­i­ment, and it is high­ly unclear that the results would be repli­cat­ed in human beings con­sum­ing cin­na­mon. Many such promis­ing exper­i­ments fail when test­ed with humans- which is why it is much wis­er to pay more atten­tion to ran­dom­ized tri­als con­duct­ed with humans, and less to “fla­vor of the day”  news coverage.

The cov­er­age around this study was indeed a good exam­ple of how sci­ence can trav­el too fast from lab to news head­lines. Because of the gen­er­al inter­est in find­ing a cure for Alzheimer’s dis­ease, results which would have nev­er got to the pub­lic eye before –because they are many steps away from a real solu­tion– now find them­selves on the front page. And the aver­age read­er does­n’t know what to do with the arti­cle. Is it rel­e­vant to me today? How does it com­pare to the arti­cle I read last week talk­ing about XYZ?

And this is why we need well-informed and sharp news read­ers, and reporters. For any study report­ed one should always ask these questions:

1. Was the study con­duct­ed with human beings, ide­al­ly fac­ing sim­i­lar cir­cum­stances to mine?
2. How many par­tic­i­pants were involved? (The more par­tic­i­pants the more reli­able the results.)
3. Is the jour­nal in which the study was pub­lished a well-known jour­nal? If you do not know, you can use PubMed and oth­er online data­base as an indicator.
4. Does the study report a cor­re­la­tion (peo­ple who smoke are at high­er risks of Alzheimer’s) or actu­al causal­i­ty (when com­par­ing a group of peo­ple who par­tic­i­pat­ed in Inter­ven­tion A and a group who did not, it was observed that Inter­ven­tion A had pos­i­tive and causal effects on brain health)? Cor­re­la­tions are often mean­ing­less for deci­sion-mak­ing, because they do not imply cau­sa­tion and one does­n’t know the direc­tion of the relationship.

For more tips on how to become an informed sci­ence and news read­er, you check out The Sharp­Brains Guide to Brain Fit­ness: How to Opti­mize Brain Health and Per­for­mance at Any Age, which devotes an entire chap­ter to how to under­stand and nav­i­gate lat­est sci­en­tif­ic research (and anoth­er one to the role of nutri­tion and supplements).
— This arti­cle was writ­ten by Pas­cale Mich­e­lon, PhD. Dr. Mich­e­lon was a Research Sci­en­tist at Wash­ing­ton Uni­ver­sity in Saint Louis, where she is now an Adjunct Fac­ulty. She is a co-author of the new book The Sharp­Brains Guide to Brain Fit­ness: How to Opti­mize Brain Health and Per­for­mance at Any Age (April 2013).