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Memory Training Reduces Brain Atrophy

Numer­ous stud­ies show ben­e­fits of cog­ni­tive train­ing in older adults, despite a recent study ques­tion­ing their valid­ity. The debate on the effects of spe­cific cog­ni­tive inter­ven­tions is not settled.

A find­ing that researchers do seem to agree on is that aging is accom­pa­nied by brain and cog­ni­tive decline. These reduc­tions seem to be mod­i­fi­able through cog­ni­tive and phys­i­cal exer­cise. In this vein, our lab recently demon­strated that older adults involved in an 8-week mem­ory train­ing pro­gram show less brain atro­phy. This gives some hope for older adults won­der­ing whether their train­ing efforts are really worthwhile.

A major research inter­est in our lab is how brain struc­ture and mem­ory change across the human life-span. We have recently been able to mea­sure regional changes in the brain within the same older adults over time. In a recent study, my super­vi­sor, Anders Fjell and col­leagues found that nor­mal aging Amer­i­cans (about 60 years old) show regional brain atro­phy (shrink­age) of about — 0.5 – 1.0 % after only one year.

The rea­son why the brain atro­phies (shrinks in size) with age is not com­pletely under­stood. An old myth about aging is that we lose neu­rons as we age. This does not seem to hold true for healthy older adults. Instead, researchers cur­rently believe that the atro­phy is more likely to be dri­ven by 1) nerve cells shrink­ing and 2) loss of con­nec­tions between nerve cells

Not only brain size, but also cog­ni­tive per­for­mance declines as we age. Abil­i­ties like pro­cess­ing speed and long-term mem­ory declines steadily. How­ever, the pace of aging varies greatly among older indi­vid­u­als. Thus, a cen­tral pur­suit in con­tem­po­rary neu­ro­science is to under­cover mod­i­fiers of the aging process.

Var­i­ous fac­tors are found to be asso­ci­ated with age-related dif­fer­ences in brain struc­ture and cog­ni­tion. Your genetic makeup seems to be impor­tant. Also what socioe­co­nomic back­ground and edu­ca­tional level you have plays a role.

Lately and thor­oughly reviewed in the Sharp­brains blog ear­lier, lifestyle and behav­ior seem to have a sig­nif­i­cant impact. One exam­ple is nutri­tion. In fact, David Smith and col­leagues in Oxford showed ear­lier this fall that older adults with mild cog­ni­tive impair­ment have less brain atro­phy if they take a vitamin-B sup­ple­ment regularly.

Other lifestyle fac­tors con­tribut­ing to indi­vid­ual age-differences in both brain and cog­ni­tive func­tion are phys­i­cal and men­tal exer­cise or brain train­ing. The basis for how these influ­ence the aging process is based on the con­cept of brain plas­tic­ity. Brain plas­tic­ity is a mul­ti­fac­eted con­cept, but can be described as your brain’s abil­ity to change struc­turally and func­tion­ally at any age.

In our lab we were fas­ci­nated by this abil­ity and asked the fol­low­ing ques­tion: Could mem­ory train­ing impact the brain atro­phy that takes place in the aging brain? With this in mind, my research group set out to inves­ti­gate the effects of a mem­ory train­ing pro­gram for healthy middle-aged and older adults (mean age = 60 years).

Through a news­pa­per add, we recruited more than 40 par­tic­i­pants and divided them ran­domly into a mem­ory train­ing and con­trol group. The mem­ory train­ers par­tic­i­pated in an 8-week pro­gram where they learned a visual mnemonic tech­nique known as the Method of loci. Using this tech­nique the par­tic­i­pants had to learn and recall new ver­bal infor­ma­tion almost every­day, like the names of Amer­i­can pres­i­dents, Roman emper­ors, mem­bers of par­lia­ment, and the order of coun­tries in South-America.

After 8-weeks of train­ing, we found that:

a) the mem­ory train­ers improved sig­nif­i­cantly in their abil­ity to remem­ber ver­bal infor­ma­tion in a par­tic­u­lar sequence (for instance the name of the 1st or 10th Amer­i­can pres­i­dent). How­ever, they did not improve more on other domains of mem­ory func­tion than the con­trol group, which is in-line with other studies.

b) the thick­ness of the cere­bral cor­tex increased in sev­eral regions of the brain among those who had trained their mem­ory func­tion. Also, par­tic­i­pants who had improved the most on the spe­cific mem­ory test where the ones with the most increase in cor­ti­cal (brain) thickness.

The four regions of the brains in which mem­ory train­ing increased cor­ti­cal thick­ness are illus­trated below. Two effects were located in the frontal lobes (lat­eral orbitofrontal cor­tex), and one in the fusiform region of the right tem­po­ral lobe.

Fig­ure 1. The fig­ure show the strength of the effects mapped on a tem­plate brain. Top row is the right hemi­sphere in lat­eral (from out­side), ven­tral (from under) and medial (from inside) views.

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The changes in cor­ti­cal thick­ness in the con­trol and train­ing groups are shown in the sec­ond fig­ure below. You can see that the con­trol group decreased slightly, whereas the mem­ory train­ers increased. Also note that the changes are small (less than 0.05 mm in most areas).

Fig­ure 2. Bar plots of the group-changes in cor­ti­cal thick­ness. The green bars are the con­trol group, the blue col­ors are the train­ing group. Lighter col­ors are the aver­age thick­ness at follow-up.

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What do these find­ings tell us? It seems as middle-aged and older adults who train their mem­ory vig­or­ously in a 2-month period have dif­fer­ent, more pos­i­tive changes in brain struc­ture, com­pared with those who do not. The ones who had bet­ter mem­ory improve­ments also had more pos­i­tive changes in the brain. The effects on mem­ory per­for­mance were pos­i­tive, but the trans­fer effect was seen on brain struc­ture only. We did not look at the effects beyond the 2-months, and we are wait­ing to see whether cog­ni­tive exer­cise indeed alters the way our brains age in the long-term. Since our study was pub­lished, other very recent stud­ies have shown that cog­ni­tive exer­cise in the elderly can also mod­ify the blood flow to, and the under­ly­ing nerve fibers (white mat­ter) of the frontal lobes.

Mem­ory train­ing improves spe­cific mem­ory func­tions, but also seems to make pos­i­tive changes in the aging brain such as less atro­phy and even increased cor­ti­cal thick­ness. These results strengthen the con­clu­sions about the value of men­tal exer­cise for older adults.

— Andreas Engvig was an intern at Sharp­brains a cou­ple of years ago. He is now a MD-PhD can­di­date in the Cen­ter for the Study of Human Cog­ni­tion at the Uni­ver­sity of Oslo, Nor­way. He is cur­rently pur­su­ing his PhD inves­ti­gat­ing the effects of mem­ory train­ing on aging brain struc­tures. His first pub­li­ca­tion recently achieved 8th place in Neuroimage’s “Top 25 Hottest Arti­cles” list.

Ref­er­ences

  • Engvig, A., Fjell, A.M., West­lye, L.T., Mober­get, T., Sund­seth, O., Larsen, V.A., Wal­hovd, K.B., 2010. Effects of mem­ory train­ing on cor­ti­cal thick­ness in the elderly. Neu­roIm­age 52, 1667–1676.
  • Engvig, A., Fjell, A.M., West­lye, L.T., Mober­get, T., Sund­seth, O., Larsen, V.A., Wal­hovd, K.B., sub­mit­ted man­u­script. Mem­ory train­ing impacts short-term changes in aging white matter.
  • Esiri, M.M., 2007. Age­ing and the brain. J Pathol 211, 181–187.
  • Fjell, A.M., Wal­hovd, K.B., Fennema-Notestine, C., McEvoy, L.K., Hagler, D.J., Hol­land, D., Brewer, J.B., Dale, A.M., 2009. One-year brain atro­phy evi­dent in healthy aging. J Neu­rosci 29, 15223–15231.
  • Kramer, A.F., Erick­son, K.I., 2007. Effects of phys­i­cal activ­ity on cog­ni­tion, well-being, and brain: human inter­ven­tions. Alzheimers Dement 3, S45-51.
  • Lam­precht, R., LeDoux, J., 2004. Struc­tural plas­tic­ity and mem­ory. Nat Rev Neu­rosci 5, 45–54.
  • Lov­den, M., Bodammer, N.C., Kuhn, S., Kauf­mann, J., Schutze, H., Tem­pel­mann, C., Heinze, H.J., Duzel, E., Schmiedek, F., Lin­den­berger, U., 2010. Experience-dependent plas­tic­ity of white-matter microstruc­ture extends into old age. Neu­ropsy­cholo­gia 48, 3878–3883.
  • Mozolic, J.L., Hayasaka, S., Lau­ri­enti, P.J., 2010. A cog­ni­tive train­ing inter­ven­tion increases rest­ing cere­bral blood flow in healthy older adults. Front Hum Neu­rosci 4, 16.
  • Park, D.C., Reuter-Lorenz, P., 2009. The adap­tive brain: aging and neu­rocog­ni­tive scaf­fold­ing. Annu Rev Psy­chol 60, 173–196.
  • Reid, L., MacLul­lich, A., 2006. Sub­jec­tive Mem­ory Com­plaints and Cog­ni­tive Impair­ment in Older Peo­ple. Dement Geri­atr Cogn Dis­ord 22, 471–485.
  • Smith, A.D., Smith, S.M., de Jager, C.A., Whit­bread, P., John­ston, C., Agacin­ski, G., Oul­haj, A., Bradley, K.M., Jacoby, R., Ref­sum, H., 2010. Homocysteine-lowering by B vit­a­mins slows the rate of accel­er­ated brain atro­phy in mild cog­ni­tive impair­ment: a ran­dom­ized con­trolled trial. PLoS ONE 5, e12244.
  • Valen­zuela, M., Sachdev, P., 2009. Can cog­ni­tive exer­cise pre­vent the onset of demen­tia? Sys­tem­atic review of ran­dom­ized clin­i­cal tri­als with lon­gi­tu­di­nal follow-up. Am J Geri­atr Psy­chi­a­try 17, 179–187.
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