Training of working memory in children with ADHD

Publication: Journal of Clinical and Experimental Neuropsychology, November 2002

Institution: Karolinska Institute

Investigator(s): Dr. Torkel Klingberg, Dr. Hans Forssberg, Dr. Helena Westerberg

Program: Cogmed RM


Background & Aim: Working memory (WM) is the ability to retain information for short time and manipulate that information in order to make a response. Along with inattentive, impulsive and hyperactive symptoms, children with ADHD are also known have WM impairment that is associated with impaired functioning in the frontal lobe. The aim of this study was to assess the use and evaluate the effect of a new training paradigm (intensive and adaptive working memory training) on children with ADHD and healthy adults.


Study #1

Population & Sample Size:
N = 14 children with ADHD , ages 7 -15 years

• n= 7 children in adaptive Cogmed training group

• n =7 children in non-adaptive (placebo) Cogmed training group


Design: Randomized, placebo controlled, double-blinded, test-retest

T1 = baseline, T2 = post-test



I. Treatment group improved significantly over placebo control group on:

1)    Trained visuo-spatial WM task

2)    Non-trained visuo-spatial WM task (Span Board; Corsi Block Test)

3)    Nonverbal reasoning task (Raven’s Colored Progressive Matrices)

4)    Response inhibition task (Stroop)

5)    Hyperactivity (# of head movements during Continuous Performance Test (CPT)) Data was collected using an infrared camera and is believed to provide an objective measure of ‘fidgetiness’. These children also showed an average reduction in head movements during the CPT of nearly 75% and all seven children showed a reduction.


Study # 2

Population & Sample Size: N = 4 healthy adults, ages 20 -29 years

• n = 4 adults in adaptive Cogmed training group

Design: Test-retest

T1 = baseline, T2 = post-test



I. Treatment group improved significantly over their baseline performance on:

1) Trained visuo-spatial WM task

2) Non-trained visuo-spatial WM task (Span Board; Corsi Block Test)

3) Nonverbal reasoning task (Raven’s Advanced Progressive Matrices)

4) Response inhibition task (Stroop)

5) Reaction time (Continuous Performance Test; CPT)


Summary and Implications: This study by Klingberg et al. demonstrated for the first time that an individual’s WM capacity is not only flexible but also, that it can be increased with intensive and adaptive training. Importantly, improvements in WM capacity were not limited to tasks on which training occurred, but were also observed for non-trained tasks of working memory and measures of other cognitive functions. Furthermore, similar gains were observed in both ADHD children and healthy young adults. For both groups, the improvement found on the Ravens, a reliable measure of non-verbal intelligence, was striking. These gains may reflect the fact that complex reasoning skills depend on WM and that training induced improvement in WM facilitated improvements in participants’ reasoning abilities.

While these are exciting results, the study has limitations that are important to recognize. First, the sample size in both studies was small and replication with larger samples would thus be important. Second, the researchers did not examine whether children with ADHD were observed to show reduced ADHD symptoms by their parents and teachers. Although the gains made in several measures of cognitive functioning are noteworthy, it should not be assumed that similar gains in behavioral functioning and classroom performance would also occur. As the researchers note, this would be important to document in subsequent research.

Finally, the improvements observed were all based on testing that occurred immediately after training. The durability of training effects is thus unknown and determining this will require a new investigation that includes a longer-term follow-up.

Funding: This work was funded by Jeansson Stiftelse, The Swedish Medical Research Foundation, HjaÈrnfonden, Svenska DyslexifoÈreningen, Sven Jerrings Stiftelse, Frimurarna Barnahuset, and SaÈllskapet BarnavaÊrd. Training program, investigator training, and technical support provided by Cogmed. No funding provided by Cogmed.

For more information on the work of Dr. Klingberg, click here.

For an overview of the foundational research behind Cogmed, click here.