A few eter­nal ques­tions:
– Is caf­feine good for the brain?
– Does it boost cog­ni­tive func­tions?
– Does it pro­tect against dementia?

There is lit­tle doubt that drink­ing that morn­ing cup of cof­fee will likely increase alert­ness, but the main ques­tions that research is try­ing to answer go beyond that. Basi­cally: is there a sus­tained, life­time, ben­e­fit or harm from drink­ing cof­fee regularly?

The answer, so far, con­tains good news and bad news. The good news for cof­fee drinkers is that most of the long-term results are direc­tion­ally more pos­i­tive than neg­a­tive, so no clear harm seems to occur. The bad news is that it is not clear so far whether caf­feine has ben­e­fi­cial effects on gen­eral brain func­tions, either short-term or long-term (aged-related decline or risks of dementia).

It is impor­tant to note that many of the stud­ies show­ing an effect of cof­fee con­sump­tion on brain func­tions or risks of demen­tia report a cor­re­la­tion or asso­ci­a­tion (they are not ran­dom­ized clin­i­cal tri­als). As you know, cor­re­la­tion doesn’t prove cau­sa­tion: cof­fee drinkers may seem to do well in a num­ber in these long-term stud­ies, but there may be other rea­sons why cof­fee drinkers do better.

Q: How does caf­feine affect my brain?
A: Caf­feine is a stimulant.

It belongs to a chem­i­cal group called xan­thine. Adeno­sine is a nat­u­rally occur­ring xan­thine in the brain that slows down the activ­ity of brain cells (neu­rons). To a neu­ron, caf­feine looks like adeno­sine. It is there­fore used by some neu­rons in place of adeno­sine. The result is that these neu­rons speed up instead of slow­ing down.

This increased neu­ronal activ­ity trig­gers the release of the adren­a­line hor­mone, which will affect your body in sev­eral ways: your heart­beat increases, your blood pres­sure rises, your breath­ing tubes open up, sugar is released in the blood­stream for extra energy.

In mod­er­ate doses (a few cups a day) caf­feine can increase alert­ness but also reduce fine motor coor­di­na­tion, cause insom­nia, cause headaches and nervousness.

Q: Does caf­feine boost brain functions?

A: To date 3 stud­ies sug­gest that the answer is “maybe”.

In one study of over 7000 peo­ple, results showed a cor­re­la­tion between cur­rent caf­feine intake and bet­ter per­for­mance on 4 tests. This was more pro­nounced in older indi­vid­u­als than in younger ones (Mar­tin, 1993).

Another study showed that in 1500 peo­ple over 65, life-time con­sump­tion of cof­fee was asso­ci­ated with increased per­for­mance in 6 out 12 tests. Cur­rent intake was related to bet­ter per­for­mance in only 2 out 12 tests (Johnson-Kozlow, et al., 2002).

The third study showed for a group of 1875 adults aged 24 to 81, cur­rent intake of cof­fee was asso­ci­ated with bet­ter per­for­mance in 2 tests but not in 4 oth­ers. (Hameleers et al., 2000)

Thus, caf­feine con­sump­tion may be asso­ci­ated with bet­ter per­for­mance but 1) there are only very few stud­ies so far, 2) this effect seems lim­ited to some tasks only.

Q: Does caf­feine pro­tect against age-related cog­ni­tive decline?

A: Two stud­ies say “yes” and 3 stud­ies say “no”.

Van Gelder et al. (2007) fol­lowed 676 elderly men over 10 years and found that those who drank more cof­fee showed less decline in the Mini-Mental Test. The least decline was observed with 3 cups a day.

Ritchie et al. (2007) showed that over 4 years, women over 65 (but not men) who drank more than 3 cups a day showed less decline than women who drank one cup or less. This was observed only in a task of ver­bal memory.

Van Box­tel et al. (2003) fol­lowed 1376 indi­vid­u­als aged 24 to 81 for 6 years and found that caf­feine intake had a very small impact on a motor task but no effect on ver­bal mem­ory tasks.

Hameleers et al. (2000) found no evi­dence that caf­feine intake coun­ter­acts cog­ni­tive age-related decline in a group of 1875 peo­ple aged 24 to 81.

The most recent study of 2606 peo­ple showed that over 28 years cof­fee drink­ing was not related to bet­ter per­for­mance (Laitala et al., 2009).

As you can see results are mixed. The evi­dence show­ing that caf­feine reduces age-related cog­ni­tive decline is lim­ited: very few stud­ies and very few tasks.

Q: Does caf­feine pro­tect against dementia?

A: Three stud­ies say “yes” and 2 stud­ies say “no”.

Maia et al. (2002) stud­ied 54 Alzheimer’s patients and their non-affected rel­a­tives (Con­trols): Higher daily caf­feine intake dur­ing the 20 years prior diag­no­sis was found to be asso­ci­ated with lower risk of Alzheimer’s Dis­ease, sug­gest­ing that cof­fee may be protective.

Eske­li­nen et al. (2009) fol­lowed 1409 indi­vid­u­als aged 65 to 79 for 21 years and found that those who drank cof­fee had less risk of devel­op­ing demen­tia than those who didn’t. The low­est risk was in peo­ple drink­ing 3–5 cups a day.

Lind­say et al (2002) stud­ied 4615 indi­vid­u­als over 5 years and found that cof­fee con­sump­tion was asso­ci­ated with a reduced risk of Alzheimer’s Disease.

Ritchie et al. (2007) stud­ied 7017 indi­vid­u­als aged 65 and over and showed that, over 4 years, caf­feine con­sump­tion did not reduce demen­tia risk.

The most recent study to date showed that over 28 years, cof­fee drink­ing did not affect the risk of mild cog­ni­tive impair­ment or demen­tia (Laitala et al., 2009).

Here again the evi­dence is mixed. Based on the few stud­ies, it is not pos­si­ble at this time to say that cof­fee con­sump­tion indeed decreases the risks of dementia.

– Pas­cale Mich­e­lon, Ph. D., is Sharp­Brains’ Research Man­ager for Edu­ca­tional Projects. 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.

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