Comparing Working Memory Training & Medication Treatment for ADHD

Work­ing mem­o­ry (WM) is the cog­ni­tive sys­tem respon­si­ble for the tem­po­rary stor­age and manip­u­la­tion of infor­ma­tion and plays an impor­tant role in both learn­ing and focus­ing atten­tion. Con­sid­er­able research has doc­u­ment­ed that many chil­dren and adults with ADHD have WM deficits and that this con­tributes to dif­fi­cul­ties asso­ci­at­ed with the dis­or­der. For an excel­lent intro­duc­tion to the role of WM deficits in ADHD, click here.

A sim­ple exam­ple illus­trates the impor­tance of WM for par­tic­u­lar aca­d­e­m­ic tasks. Try adding 3 and 9 in your head. That was prob­a­bly easy for you. Now try­ing adding 33 and 99. That was prob­a­bly more dif­fi­cult. Final­ly, try adding 333 and 999. This is quite chal­leng­ing for most adults even though each cal­cu­la­tion required is triv­ial­ly easy. The chal­lenge occurred because you need to store infor­ma­tion — the sum of 3+9 in the one’s col­umn and then ten’s col­umn — as you process the remain­ing part of the prob­lem, i.e., 3+9 in the hun­dred’s col­umn, and this taxed your WM. If your WM capac­i­ty was exceed­ed, you could not com­plete the prob­lem successfully.

This sim­ple prob­lem also illus­trates the dif­fer­ence between short-term mem­o­ry (STM) and WM. Short-term mem­o­ry sim­ply involves retain­ing infor­ma­tion in mind for short peri­ods of time, e.g., remem­ber­ing that the prob­lem you need to solve is 333+999. Work­ing mem­o­ry, in con­trast, involves men­tal­ly manip­u­lat­ing — or ‘work­ing’ with — retained infor­ma­tion and comes into play in a wide range of learn­ing activ­i­ties. For exam­ple, to answer ques­tions about a sci­ence chap­ter, a child not only has to cor­rect­ly retain fac­tu­al infor­ma­tion but must men­tal­ly work with that infor­ma­tion to answer ques­tions about it. Thus, when a child’s WM capac­i­ty is low rel­a­tive to peers, aca­d­e­m­ic per­for­mance is like­ly to be com­pro­mised in mul­ti­ple areas.

Because WM deficits play an impor­tant role in the strug­gles expe­ri­enced by many indi­vid­u­als with ADHD, it is impor­tant to con­sid­er how dif­fer­ent inter­ven­tions address this aspect of the dis­or­der. In this study, the authors were inter­est­ed in com­par­ing the impact of Work­ing Mem­o­ry Train­ing and stim­u­lant med­ica­tion treat­ment on the WM per­for­mance of chil­dren diag­nosed with ADHD.

Par­tic­i­pants were 25 8–11 year-old chil­dren with ADHD (21 boy and 4 girls) who were being treat­ed with stim­u­lant med­ica­tion. Chil­dren’s mem­o­ry per­for­mance was assessed on 4 occa­sions using the Auto­mat­ed Work­ing Mem­o­ry Assess­ment (AWMA), a com­put­er­ized test that mea­sures ver­bal short-term mem­o­ry, ver­bal work­ing mem­o­ry, visuo-spa­tial short-term mem­o­ry, and visuo-spa­tial work­ing memory.

At time 1, the assess­ment was con­duct­ed when chil­dren had been off med­ica­tion for at least 24 hours. The sec­ond assess­ment occurred an aver­age of 5 months lat­er and when chil­dren were on med­ica­tion. The third assess­ment occurred after chil­dren had com­plet­ed 5 weeks of Cogmed Work­ing Mem­o­ry Train­ing using the stan­dard train­ing pro­to­col (see below). The final assess­ment occurred approx­i­mate­ly 6 months after train­ing had end­ed. This design enabled the researchers to make the fol­low­ing comparisons:

- WM per­for­mance on med­ica­tion vs. off med­ica­tion (T1 vs T2)
— WM per­for­mance on med­ica­tion vs. after train­ing (T2 vs. T3)
— WM per­for­mance imme­di­ate­ly after train­ing end­ed vs. 6 months fol­low­ing train­ing (T3 vs. T4)

This final com­par­i­son pro­vid­ed infor­ma­tion on whether any ben­e­fits pro­vid­ed by the train­ing had endured.

In addi­tion to mea­sur­ing STM and WM at each time point, mea­sures of IQ were col­lect­ed at times 1, 2, and 3.

- Work­ing Mem­o­ry Train­ing -

WM train­ing was con­duct­ed using the stan­dard Cogmed train­ing pro­to­col with each child com­plet­ing 20–25 train­ing ses­sions with­in a 25 day peri­od. The train­ing requires the stor­age and manip­u­la­tion of sequences of ver­bal, e.g., repeat­ing back a sequence of dig­its in reverse order, and/or visuo-spa­tial infor­ma­tion, e.g., recall­ing the loca­tion of objects on dif­fer­ent por­tions of the com­put­er screen.

Dif­fi­cul­ty lev­el is cal­i­brat­ed on a tri­al by tri­al basis so the child is always work­ing at a lev­el that close­ly match­es their per­for­mance. For exam­ple, if a child suc­cess­ful­ly recalled three dig­its in reverse order, on the next tri­al he had to recall four. When a tri­al was failed, the next tri­al was made eas­i­er by reduc­ing the num­ber of items to be recalled. This method of ‘adap­tive train­ing’ is thought to be a key ele­ment because it requires the child to ‘stretch’ their WM capac­i­ty to move through the program.

- Results -

- Impact of Short-Term Mem­o­ry and Work­ing Mem­o­ry -

Med­ica­tion vs. no med­ica­tion — When test­ed on med­ica­tion, chil­dren showed bet­ter visuo-spa­tial WM rel­a­tive to when they were test­ed off med­ica­tion. How­ev­er, no improve­ment was found for ver­bal STM, ver­bal WM, or visuo-spa­tial STM.

Per­for­mance on med­ica­tion vs. per­for­mance after WM train­ing — Cogmed WM Train­ing led to sig­nif­i­cant gains in all four mem­o­ry scores. Thus, there was evi­dence that WM train­ing led to greater gains in WM that med­ica­tion treat­ment alone. On all areas of mem­o­ry assessed, the aver­age score of par­tic­i­pants had moved from below aver­age to with­in the aver­age range.

Per­for­mance 6 months after train­ing end­ed — Train­ing gains in 3 of the 4 mem­o­ry com­po­nents — all but visuo-spa­tial STM — remained sig­nif­i­cant 6 months after train­ing had end­ed and there was lit­tle indi­ca­tion of any decline in chil­dren’s per­for­mance. Thus, the ben­e­fits evi­dent imme­di­ate­ly fol­low­ing train­ing had large­ly persisted.

- Impact on IQ -

IQ results on and off med­ica­tion were equiv­a­lent. Like­wise, there was no indi­ca­tion that WM train­ing was asso­ci­at­ed with any increase in chil­dren’s IQ results. Thus, the ben­e­fits of train­ing were restrict­ed to chil­dren’s per­for­mance on the mem­o­ry tasks.

- Sum­ma­ry and Impli­ca­tions -

Results from this study indi­cate that WM train­ing yields greater ben­e­fits in WM for chil­dren with ADHD than are pro­vid­ed by stim­u­lant med­ica­tion treat­ment. Fur­ther­more, mem­o­ry gains fol­low­ing train­ing per­sist for a sig­nif­i­cant peri­od. Because ade­quate WM func­tion­ing is crit­i­cal­ly impor­tant for chil­dren’s aca­d­e­m­ic suc­cess, these are encour­ag­ing find­ings as they sug­gest that inten­sive train­ing can ame­lio­rate deficits in this impor­tant exec­u­tive func­tion. The absence of train­ing ben­e­fits on IQ sug­gests that the ben­e­fits of train­ing may be lim­it­ed to WM specif­i­cal­ly, although it should be not­ed that oth­er WM train­ing stud­ies have report­ed ben­e­fits on par­tic­u­lar aspects of intel­li­gence. Thus, the impact of WM train­ing on IQ requires fur­ther study.

How­ev­er, it is impor­tant not to over inter­pret the results from this study. While it is tempt­ing to regard this as a com­par­i­son of med­ica­tion treat­ment and WM train­ing for ADHD, and to view the results as indi­cat­ing the supe­ri­or­i­ty of the lat­ter, this would be an erro­neous inter­pre­ta­tion. The con­stel­la­tion of dif­fi­cul­ties that com­prise ADHD for many chil­dren extend sig­nif­i­cant­ly beyond WM deficits, and this study did not exam­ine a num­ber of oth­er impor­tant outcomes.

For exam­ple, it pro­vides no infor­ma­tion on the rel­a­tive ben­e­fits of med­ica­tion and WM train­ing on chil­dren’s atten­tion, hyper­ac­tiv­i­ty, oth­er behav­ior prob­lems, and aca­d­e­m­ic per­for­mance. Even though oth­er stud­ies of WM train­ing have found ben­e­fits in sev­er­al of these areas, adding assess­ments of these crit­i­cal out­comes to the cur­rent study would have strength­ened it. This crit­i­cism is not intend­ed to dis­count the impor­tant results obtained, but to instead pro­vide an appro­pri­ate con­text for eval­u­at­ing these inter­est­ing find­ings and it would not be sur­pris­ing if med­ica­tion treat­ment were to have greater impact in oth­er impor­tant areas.

It is also the case that the study was lim­it­ed by restrict­ing the assess­ment of WM to com­put­er­ized mea­sures of this capac­i­ty, even though val­i­dat­ed par­ent and teacher rat­ing scale mea­sures of WM are avail­able. Incor­po­rat­ing such mea­sures into the study would have pro­vid­ed a more com­pre­hen­sive of chil­dren’s mem­o­ry func­tion­ing at each assess­ment point.

Although these rep­re­sent impor­tant study lim­i­ta­tions, the results pro­vide addi­tion­al evi­dence that inten­sive WM train­ing can yield endur­ing ben­e­fits in this key exec­u­tive func­tion. Because the ben­e­fits pro­vid­ing by train­ing enhance those pro­vid­ed by med­ica­tion, it also sug­gests that WM train­ing may be a use­ful com­ple­ment to exist­ing evi­dence-based inter­ven­tions for ADHD, par­tic­u­lar­ly for chil­dren whose WM func­tion­ing is lim­it­ed to begin with.

– Dr. David Rabin­er is a child clin­i­cal psy­chol­o­gist and Direc­tor of Under­grad­u­ate Stud­ies in the Depart­ment of Psy­chol­ogy and Neu­ro­science at Duke Uni­ver­sity. He pub­lishes Atten­tion Research Update, an online newslet­ter that helps par­ents, pro­fes­sion­als, and edu­ca­tors keep up with the lat­est research on ADHD, and teach­es the online course  How to Nav­i­gate Con­ven­tion­al and Com­ple­men­tary ADHD Treat­ments for Healthy Brain Devel­op­ment.

Relat­ed arti­cles by Dr. Rabiner

- Neurofeedback/ Quan­ti­ta­tive EEG for ADHD diagnosis

- Promis­ing Cog­ni­tive Train­ing Stud­ies for ADHD

- Mind­ful­ness Med­i­ta­tion for Adults & Teens with ADHD

- Self-Reg­u­la­tion and Barkley’s The­o­ry of ADHD