Are mentally-stimulating activities good or bad for the brain? The true story.

With World Alzheimer’s Day com­ing up (Sept 21st), it seemed impor­tant to make sense of the sci­en­tif­ic study pub­lished this month that has trig­gered head­lines claim­ing that “Doing puz­zles could speed up demen­tia”, “Brain Exer­cise may wors­en exist­ing Alzheimer’s” and even explain­ing to read­ers “Why you should­n’t play men­tal­ly stim­u­lat­ing games”.

What is the mat­ter?  Pre­vi­ous stud­ies had shown it to be quite clear that peo­ple who lead a men­tal­ly or cog­ni­tive­ly stim­u­lat­ing life also tend to:

a) ben­e­fit from improved think­ing and over­all cog­ni­tive func­tion­ing (delayed cog­ni­tive decline)

b) have reduced risks of man­i­fest­ing Alzheimer’s dis­ease symptoms

The new study, pub­lished in Neu­rol­o­gy by Dr. Wil­son from the Rush Alzheimer’s Dis­ease Cen­ter fol­lowed more than 2,000 indi­vid­u­als 65 and over for 12 years. How often they par­tic­i­pat­ed in cog­ni­tive activ­i­ties such as read­ing (book, mag­a­zines, news­pa­pers), play­ing games (cards, cross­words, etc.), watch­ing TV and going to a muse­um was first assessed. Each indi­vid­ual received a score on this cog­ni­tive activ­i­ty scale. Six years lat­er clin­i­cal eval­u­a­tion was con­duct­ed to deter­mine who was still high­ly func­tion­ing (all indi­vid­u­als start­ed demen­tia free), who was suf­fer­ing from mild cog­ni­tive impair­ment and who had Alzheimer Dis­ease.  The cog­ni­tive decline of indi­vid­u­als in these three cat­e­gories (1,157 par­tic­i­pants total) was then assessed over an aver­age of 6 years.

This study is dif­fer­ent from the pre­vi­ous ones show­ing that healthy peo­ple who are cog­ni­tive­ly active have low­er risks of devel­op­ing demen­tia for one major rea­son: It assessed the fate of cog­ni­tive­ly active indi­vid­u­als who have been diag­nosed with dementia.

This stress­es an impor­tant point: cog­ni­tive activ­i­ty helps delay the emer­gence of demen­tia but doesn’t pre­vent it completely.

The results of the study con­firmed that cog­ni­tive activ­i­ty pri­or to demen­tia onset is pro­tec­tive: the annu­al rate of glob­al cog­ni­tive decline for peo­ple who had no cog­ni­tive impair­ment was reduced by 52% for each addi­tion­al point on the cog­ni­tive activ­i­ty scale.

This means that indi­vid­u­als who had high cog­ni­tive activ­i­ty scores showed delayed decline. Over­all these indi­vid­u­als declined more slow­ly than indi­vid­u­als who were less cog­ni­tive­ly active in the past. This also sug­gests that if these indi­vid­u­als were to devel­op demen­tia the onset of the dis­ease would be delayed.

The oth­er major result of the study is that once peo­ple who had high cog­ni­tive activ­i­ty scores are diag­nosed with Alzheimer they show com­pressed rates of decline.

This means that, after diag­no­sis, com­pared to less cog­ni­tive­ly active peo­ple they will decline faster. Indeed the mean rate of cog­ni­tive decline per year for peo­ple in the Alzheimer group increased by 42% for each addi­tion­al point on the cog­ni­tive activ­i­ty scale.

Note that for indi­vid­u­als in the Mild Cog­ni­tive Impair­ment group (MCI is con­sid­ered to be the very ear­ly stage of demen­tia), there was no effect of cog­ni­tive activ­i­ty on decline.

Fig­ure. This is a sim­ple graph­ic rep­re­sen­ta­tion of the results, shown on a time line. Indi­vid­u­als cog­ni­tive­ly active before the study began (A) are rep­re­sent­ed by the top line. Indi­vid­u­als less cog­ni­tive­ly active before the study began (B) are rep­re­sent­ed by the bot­tom line. The thick line rep­re­sents the time that indi­vid­u­als live with­out impair­ment. The red mark rep­re­sents Alzheimer’s diag­no­sis. The thin line rep­re­sents the time that indi­vid­u­als live with dementia.

Are these results a big sur­prise? Does it mean that men­tal­ly stim­u­lat­ing activ­i­ties are bad for the brain? No! As Dr. Wil­son explained to us “Say­ing that cog­ni­tive activ­i­ty wors­ens demen­tia is tak­ing the results out of context.”

Here is a sim­ple expla­na­tion of the results:

• Fre­quent cog­ni­tive activ­i­ty stim­u­lates dif­fer­ent parts of the brain involved in mem­o­ry and infor­ma­tion pro­cess­ing. These parts of the brain become more resis­tant and more effi­cient. Cog­ni­tive reserve is built. If demen­tia is not present, nor­mal cog­ni­tive decline is slow­er. If demen­tia is present, the brain can tol­er­ate more demen­tia-relat­ed pathol­o­gy and still func­tion normally.

Con­se­quence: In healthy peo­ple, more fre­quent cog­ni­tive activ­i­ty is relat­ed to delayed and slow­er cog­ni­tive decline. Even if Alzheimer’s pathol­o­gy is devel­op­ing in the brain, the symp­toms will not show until lat­er. Demen­tia onset is thus post­poned. Whether pathol­o­gy is present in the brain or not, engag­ing in cog­ni­tive activ­i­ty con­tributes to delay a decline that oth­er­wise would occur.

• The brain can tol­er­ate pathol­o­gy only to a cer­tain point. Cog­ni­tive­ly active peo­ple who are diag­nosed with demen­tia have reached a thresh­old of pathol­o­gy at which it would be very hard to func­tion nor­mal­ly. So when they are diag­nosed with demen­tia cog­ni­tive­ly active peo­ple have more pathol­o­gy in the brain than less active peo­ple when they are diag­nosed with dementia.

Con­se­quence: For peo­ple who are now liv­ing with Alzheimer, hav­ing par­tic­i­pat­ed in cog­ni­tive­ly engag­ing activ­i­ties before the dis­ease leads to com­pressed rates of decline. Giv­en that they were diag­nosed lat­er com­pared to less active peo­ple, the pathol­o­gy is more advanced in their brain and they will live less time with the disease.

We know that noth­ing can pre­vent Alzheimer’s Dis­ease. How­ev­er, as con­firmed in this study, cog­ni­tive activ­i­ty helps delay the onset of demen­tia. Since the decline expe­ri­enced by cog­ni­tive­ly active peo­ple is faster after diag­no­sis, does it make sense to say that cog­ni­tive exer­cise wors­en demen­tia expe­ri­ence? In fact it seems the oppo­site. These indi­vid­u­als seem to spend less time expe­ri­enc­ing the symp­toms as these start show­ing lat­er, when the pathol­o­gy in the brain is already quite advanced. This is a huge ben­e­fit both from the point of view of the indi­vid­ual, the care­givers, and health costs overall.

As Dr. Wil­son puts it the results can be explained in terms of “buy­ing extra-time liv­ing as a high­ly func­tion­al indi­vid­ual and spend­ing less time liv­ing with dementia.”

Dr. Daniel Good­man, a psy­chi­a­trist prac­tic­ing in New York and Green­wich and an active par­tic­i­pant  in the LinkedIn Sharp­Brains group offers the fol­low­ing choice that sum­ma­rize the sit­u­a­tion very well: If you knew you had a pro­gres­sive fatal con­di­tion (Alzheimer’s) that was def­i­nite­ly going to kill you in 10 years, then which of the fol­low­ing would you prefer:

1) Steady, grad­ual, pro­gres­sive dete­ri­o­ra­tion over 10 years, with death at that point (i.e. a slow rate of cog­ni­tive decline)

2) Symp­tom free life for 9 years, fol­lowed by rapid dete­ri­o­ra­tion in year 10 end­ing in death (i.e. an even­tu­al rapid cog­ni­tive decline, at the end stage of illness)

(Note that these num­bers are pure­ly hypothetical)

In sum this study sug­gests that engag­ing in cog­ni­tive­ly stim­u­lat­ing activ­i­ties before the age of 65 is relat­ed to:

• delayed cog­ni­tive decline and demen­tia onset
• if diag­nosed, reduced num­ber of years liv­ing with dementia

The absence of effect of pri­or cog­ni­tive activ­i­ty in the group with mild cog­ni­tive impair­ment sug­gests that cog­ni­tive train­ing or stim­u­la­tion pro­grams may need to start before any impair­ment devel­ops to have an effect on rates of decline. How­ev­er noth­ing in this study sug­gests that peo­ple with impair­ment should not engage in stim­u­lat­ing activ­i­ties after diag­no­sis. Oth­er stud­ies have shown ben­e­fits for this pop­u­la­tion, such as bet­ter qual­i­ty of life.

If we are try­ing to find ways to boost men­tal func­tions and delay decline, this study rein­forces the idea that the ear­li­er we start the better.

What kind of activ­i­ty is the best to engaged in? In their stud­ies, Dr. Wil­son and his team delib­er­ate­ly chose activ­i­ties that were “cog­ni­tive, that is activ­i­ties involv­ing pro­cess­ing and retain­ing infor­ma­tion”. Accord­ing to Dr. Wil­son read­ing is such a pro­to­typ­i­cal activ­i­ty. So you are exact­ly on the right track as you are read­ing this!

Ref­er­ence: Wison, R. H., Barnes, L. L., Aggar­w­al, N. T., Boyle, P. A., Hebert, L. E., Mendes de Leon, C. F., & Evanc, D. A. (2010). Cog­ni­tive activ­i­ty and the cog­ni­tive mor­bid­i­ty of Alzheimer dis­ease. Neu­rol­o­gy, 75, 990–996.