ClinicalTrials.gg
Status unknownNCT03680170iPARKUpdated Jun 22, 2021

Cognitive Training in Parkinson's Disease, the iPARK Study

An interventional study of Working memory updating training and Placebo training in Parkinson Disease and Cognitive Impairment, sponsored by Umeå University. Status unknown at 1 site in Sweden. Open to participants aged 45 Years to 75 Years. Per ClinicalTrials.gov, last updated 2021-06-22.

Sponsored by Umeå University · Not applicable, Interventional, and Treatment

The sponsor has not verified this record recently (last verified Jun 2021), so the status shown — last known as Recruiting — may be out of date.

From the registry’s dates

  • Registered 1 year 2 months after the study started (first participant enrolled Feb 2017, registered Apr 2018).
Phase
Not applicable
Study type
Interventional
Enrollment
80
Allocation
Randomized
Ages
45 Years to 75 Years
Sex
All
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Study summary

The aim of the iPARK-study is to investigate the effects of a process-based cognitive training program with focus on working memory in patients with Parkinson's Disease (PD). The study is a double blinded, randomized controlled trial with a parallel group design that aim to recruit 80 persons with PD. All patients will undergo 30 sessions (6-7 weeks) of web-based cognitive training performed at home. The working memory training is a process-based training program focusing specific on updating. The placebo program is a low dose short term memory paradigm without updating. A battery of neuropsychological tests (working memory, attention, episodic memory, inhibition control, risk taking and motoric speed) and questionnaires (everyday functioning and psychological health) will be performed before training and directly after training and after 16 weeks. Patient expectation and measures of adherence (motivation and results during training) will be controlled for.

The iPARK trial is expected to provide novel and clinical useful information whether updating training is an effective training paradigm in PD. Further it will hopefully contribute to a better understanding of cognitive function in PD.

Read the detailed description

Parkinson's Disease (PD) is after Alzheimers disease (AD) the most common neurodegenerative disease with a prevalence of 1% of the population over 60 years of age. The cardinal symptoms are motoric and are believed to be caused by depletion of dopamine in the brain with severe depletion in the striatum. In addition to the motor impairments, there are several non-motor functions also affected, where cognitive decline and dementia are among the most common problems. Some claim that up to 75% of the total PD population will eventually develop dementia. Prior to dementia, milder cognitive problems are common and already at the time of diagnosis up to 42.5% of patients with PD are affected by decline in different cognitive functions. Early cognitive deficits seen is inhibition, shifting, working memory and planning, but a cognitive profile of visuospatial decline, semantic fluency and episodic memory has been connected to Parkinson's Disease Dementia (PDD). The occurrence of Lewy-bodies and Alzheimer type brain pathology is common in PDD but dopamine depletion has also been connected to cognitive decline in healthy elderly and in PD.

Although prescription of dementia medication in PD most likely has increased during the last decade there are limited evidence of treatment effects . This particular patient group is already burdened by polypharmacy and therefore investigating non-pharmacological interventions is of crucial importance. A recent systematic review of cognitive intervention studies in PD suggests that there is evidence of clinically meaningful improvements in overall cognition and moderate to large effect sizes on measures of working memory, processing speed and executive functions. Another review on the topic suggested that the results are promising, at least in the immediate or short term for some cognitive domains, but due to inconsistencies between studies and lack of methodological salience there are still a lot of questions unanswered. Baseline factors such as cognitive functioning, Hoehn and Yahr stage, premorbid intelligence all can have contributing effects on individual differences in training gain. Therefore it is important to thoroughly investigate baseline characteristics.

In the future, studies need to include more participants, be hypothesis driven and include more detail of the cognitive profile, training intervention and outcome measures.

One approach to cognitive training that has received a lot of attention and critique is process-based cognitive training, such as training focusing on working memory (WM) and executive functions (EF). The purpose of the process based approach is to strengthen general cognitive processes important to global cognitive functioning. WM and EF play central roles in several different functions such as episodic memory, reading comprehension and problem solving to mention a few. Research has also shown that WM and EF is negatively affected both in normal and pathological aging, such as PD.

Training of executive functioning and working memory have gained some promising results in healthy adults, showing improvements in working memory and executive functioning but there is also an indication of broader generalizations of training gain. Previously the effect of process-based updating training in healthy young and older individuals has been studied. Results showed that a period of updating training increased Blood Oxygen Level Dependent (BOLD) activity in striatum related to increased cognitive performance in both groups. Also a corresponding effect of training on dopaminergic neurotransmission was detected.

In the light of the dopamine dysfunction in PD, with negative effects on both motoric and cognitive function it is of interest to study if a non-invasive, non-pharmacological intervention can lead to better updating function with increased dopamine levels in patients with PD. The iPARK study is a double blinded randomized controlled trial that will examine the effect of a web-based cognitive training program with focus on updating training.

The primary question asked will be if updating training will improve the ability to update contents in working memory and also if there will be improvements in other cognitive functions such as psychomotor speed, working memory, executive functions and episodic memory. Further the aim is to investigate if there will be improvements in self-perceived everyday cognitive function and psychological health as well as if the effects seen will be sustained over a period of four months. Baseline factors will be investigated to see if they have a modulating effect on training. Further the iPARK trial will determine if a web-based training performed at home without active supervision is a feasible approach in this particular patient group. Compliance, adherence and expectations will be measured systematically.

02

Conditions studied

  • Parkinson Disease
  • Cognitive Impairment

Keywords

  • Cognitive rehabilitation
  • Working memory
  • Randomized controlled trial
  • Placebo control
03

In context

Parkinson Disease

4,583 studies on the registry are indexed under Parkinson Disease; 1,097 are open to participants now.

This study's planned enrollment of 80 is above the median of 40 across 3,365 interventional studies indexed under Parkinson Disease.

Browse Parkinson Disease studies →

Lead sponsor

Umeå University is the lead sponsor of 271 studies on the registry; 60 are open to participants now.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
45 Years to 75 Years
Sexes eligible
All
Accepts healthy volunteers
No

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

Inclusion criteria

  1. Diagnosis of Parkinson's Disease according to United Kingdom Parkinson's Disease Brain Bank (UKPDSBB) criteria
  2. Hoehn and Yahr stage I-III
  3. Pathological dat scan
  4. A score of 24 or over on the MMSE AND be without Dementia
  5. Stable medication over the past three months
  6. Owns and is able to use a home based computer or tablet with internet connection.

Exclusion criteria

Exclusion Criteria:

  1. Unstable medication
  2. Ongoing cognitive training
  3. Diagnosis of PDD
  4. Drug or alcohol abuse
05

Study design

Phase
Not applicable
Primary purpose
Treatment
Allocation
Randomized
Intervention model
Parallel assignment
Masking
Triple (Participant, Investigator, Outcomes assessor)
Enrollment
80 participants (estimated)

Study arms

  • Experimental
    Working memory updating training

    Training with web-based program on the internet for 30 sessions (4-5 times a week). The result of the training is registered. Intervention Device: web-based cognitive training

    Behavioral: Working memory updating training

  • Placebo comparator
    Placebo training

    Low dose, short term memory training. Intervention: Training with computer based program on the internet for 30 sessions (4-5 times a week). Intervention Device: Web-based cognitive training

    Behavioral: Placebo training

Interventions

  • BehavioralWorking memory updating training

    Each training session includes four working memory updating tasks that is performed at the participants home on their computer via internet. Each training session takes about 20 minutes to perform.

    Also known as: Web-based, Computer-based training, Internet-based training

  • BehavioralPlacebo training

    Each training session includes four short term memory tasks that is performed at the participants home on their computer via internet. Each training session takes about 20 minutes to perform.

    Also known as: Web-based training, Computer-based training, Internet-based training

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What researchers measure

Primary outcomes

  1. Criterion task

    Improvement on Letter memory after 30 sessions of working memory training. total score:0-40 higher score indicate better performance total items:0-10 higher score indicate better performance

    Time frame: 6-8 weeks (pretest-posttest 1)

  2. Criterion task

    Maintenance of Letter memory performance four months after completed working memory training. total score:0-40 higher score indicate better performance total items:0-10 higher score indicate better performance

    Time frame: 16 weeks (posttest 1-posttest 2)

Secondary outcomes

  1. Transfer task n-back

    Improvement on updating performance measured by n-back (1,2 and 3 back) after 30 sessions of working memory training. 1. back total score: 0-90 higher score indicate better performance 2. back total score: 0-90 higher score indicate better performance 3. back total score: 0-90 higher score indicate better performance 1 back, Yes minus false alarms: 0-36 higher score indicate better performance 2 back, Yes minus false alarms: 0-36 higher score indicate better performance 3 back, Yes minus false alarms: 0-36 higher score indicate better performance

    Time frame: 6-8 weeks (pretest-posttest 1)

  2. Transfer task n-back

    Maintenance of updating performance measured by n-back (1,2 and 3 back) four months after completed working memory training. 1. back total score: 0-90 higher score indicate better performance 2. back total score: 0-90 higher score indicate better performance 3. back total score: 0-90 higher score indicate better performance 1 back, Yes minus false alarms: 0-36 higher score indicate better performance 2 back, Yes minus false alarms: 0-36 higher score indicate better performance 3 back, Yes minus false alarms: 0-36 higher score indicate better performance

    Time frame: 16 weeks (posttest 1-posttest 2)

  3. Transfer task digit memory running span

    Improvement on updating performance measured by digit memory running span after 30 sessions of working memory training. total score:0-40 higher score indicate better performance total items:0-10 higher score indicate better performance

    Time frame: 6-8 weeks (pretest-posttest 1)

  4. Transfer task digit memory running span

    Maintenance of updating performance measured by digit memory running span four months after completed working memory training. total score:0-40 higher score indicate better performance total items:0-10 higher score indicate better performance

    Time frame: 16 weeks (posttest 1-posttest 2)

  5. Updating total score

    Improvement in calculated composite score based on z-score((raw test score-mean of group)/standard deviation of group) for digit memory running span, 2-back and 3-back. Range -4 to 4. Higher z-score indicate better updating performance. (z score(3back yes-false alarms)+z score(2back yes-false alarms)+z score (digit memory running span total))/3

    Time frame: 6-8 weeks (pretest-posttest 1)

  6. Updating total score

    Maintenance of calculated composite score based on z-score((raw test score-mean of group)/standard deviation of group) for digit memory running span, 2-back and 3-back. Range -4 to 4. Higher z-score indicate better updating performance. (z score(3back yes-false alarms)+z score(2back yes-false alarms)+z score (digit memory running span total))/3

    Time frame: 16 weeks (posttest 1-posttest 2)

  7. Transfer task episodic memory

    Improvement on episodic memory performance measured by Buschke Selective Reminding Procedure after 30 sessions of working memory training. total score: 0-74 higher score indicate better performance list learning: 0-74 delayed score:0-18 higher score indicate better performance

    Time frame: 6-8 weeks (pretest-posttest 1)

  8. Transfer task episodic memory

    Maintenance of on episodic memory performance measured by Buschke Selective Reminding Procedure four months after completed working memory training. total score: 0-74 higher score indicate better performance list learning: 0-74 higher score indicate better performance delayed score:0-18 higher score indicate better performance

    Time frame: 16 weeks (posttest 1-posttest 2)

  9. Transfer task digit span

    Improvement on working memory performance measured by Digit span forward, backwards and sequencing (WAIS IV) after 30 sessions of working memory training. digit span forward total score: 0-16 higher score indicate better performance digit span backwards total score: 0-16 higher score indicate better performance digit span sequencing total score:0-16 higher score indicate better performance

    Time frame: 6-8 weeks (pretest-posttest 1)

  10. Transfer task digit span

    Maintenance of working memory performance measured by Digit span forward, backwards and sequencing (WAIS IV) after 30 sessions of working memory training. digit span forward total score: 0-16 higher score indicate better performance digit span backwards total score: 0-16 higher score indicate better performance digit span sequencing total score:0-16 higher score indicate better performance

    Time frame: 16 weeks (posttest 1-posttest 2)

  11. Transfer task visuospatial-span

    Maintenance of visuospatial working memory performance measured by visuospatial span task, 0-18 higher score indicate better performance

    Time frame: 6-8 weeks (pretest-posttest 1)

  12. Transfer task visuospatial-span

    Maintenance of visuospatial working memory performance measured by visuospatial span task, total score 0-18 higher score indicate better performance

    Time frame: 16 weeks (posttest 1-posttest 2)

  13. working memory total score

    Improvement in calculated composite score based on z-score((raw test score-mean of group)/standard deviation of group) from digit span forward, digit span backward, digit span sequencing and visuospatial span task, higher score indicate better performance Range -4 to 4. (z score(digit span forward)+z score(digit span backward)+z score (digit span sequencing)+z score (visuospatial span task))/4

    Time frame: 6-8 weeks (pretest-posttest 1)

  14. working memory total score

    Maintenance in calculated composite score based on z-score((raw test score-mean of group)/standard deviation of group) from digit span forward, digit span backward, digit span sequencing and visuospatial span task, higher score indicate better performance. Range -4 to 4. (z score(digit span forward)+z score(digit span backward)+z score (digit span sequencing)+z score (visuospatial span task))/4

    Time frame: 16 weeks (posttest 1-posttest 2)

  15. Transfer task Matrices (WAIS IV)

    Improvement on problem solving performance measured by Matrices (WAIS IV) after 30 sessions of working memory training. total score: 0-26, higher score indicate better performance

    Time frame: 6-8 weeks (pretest-posttest 1)

  16. Transfer task Matrices (WAIS IV)

    Maintenance of problem solving performance measured by Matrices (WAIS IV) after 30 sessions of working memory training. total score: 0-26, higher score indicate better performance

    Time frame: 16 weeks (posttest 1-posttest 2)

  17. Transfer task Digit symbol

    Improvement on mental and psychomotor speed measured by Digit symbol after 30 sessions of working memory training. total score: 0-135, higher score indicate better performance

    Time frame: 6-8 weeks (pretest-posttest 1)

  18. Transfer task Digit symbol

    Maintenance of mental and psychomotor speed measured by Digit symbol four months after completed working memory training. total score: 0-135, higher score indicate better performance

    Time frame: 16 weeks (posttest 1-posttest 2)

  19. Transfer task Perdue pegboard

    Improvement in calculated mental and psychomotor speed measured by Perdue pegboard after 30 sessions of working memory training. total score right hand: 0-24, higher score indicate better performance total score left hand: 0-24 higher score indicate better performance total score both hands: 0-24higher score indicate better performance

    Time frame: 6-8 weeks (pretest-posttest 1)

  20. Transfer task Perdue pegboard

    Maintenance of mental and psychomotor speed measured by Perdue pegboard four months after completed working memory training. total score right hand: 0-24, higher score indicate better performance total score left hand: 0-24 higher score indicate better performance total score both hands: 0-24higher score indicate better performance

    Time frame: 16 weeks (posttest 1-posttest 2)

  21. Mental and psychomotor speed total score

    Improvement in calculated composite score based on z-score((raw test score-mean of group)/standard deviation of group) for Digit symbol and Perdue pegboard after 30 sessions of working memory training. higher score indicate better performance (range -4 to 4). (z score(Perdue pegboard)+z score(digit symbol))/2

    Time frame: 6-8 weeks (pretest-posttest 1)

  22. Mental and psychomotor speed total score

    Maintenance of calculated composite score based on z-score((raw test score-mean of group)/standard deviation of group) from Digit symbol and Perdue pegboard four months after completed working memory training. higher score indicate better performance. (range -4 to 4). (z score(Perdue pegboard)+z score(digit symbol))/2

    Time frame: 16 weeks (posttest 1-posttest 2)

  23. Transfer task Stroop test

    Improvement of executive functions measured by Stroop test (DKEFS) after 30 sessions of working memory training. color naming 0-90 seconds less time indicate better performance word naming 0-90 seconds less time indicate better performance inhibition 0-90 seconds less time indicate better performance Inhibition cost total score:0-90 seconds, less inhibition cost indicate better performance

    Time frame: 6-8 weeks (pretest-posttest 1)

  24. Transfer task Stroop test

    Maintenance of executive functions measured by Stroop test (DKEFS) four months after completed working memory training. color naming 0-90 seconds less time indicate better performance word naming 0-90 seconds less time indicate better performance inhibition 0-90 seconds less time indicate better performance Inhibition cost total score:0-90 seconds, less inhibition cost indicate better performance

    Time frame: 16 weeks (posttest 1-posttest 2)

  25. Transfer task Trail Making Test

    Improvement on executive functions measured by Trail Making Test A and B (DKEFS) after 30 sessions of working memory training. TMT A 0-250 seconds less time indicate better performance TMT B 0-350 seconds less time indicate better performance Shift cost (TMTB-TMTA): 0-200 seconds, less shift cost indicate better performance

    Time frame: 6-8 weeks (pretest-posttest 1)

  26. Transfer task Trail Making Test

    Maintenance of executive functions measured by Trail Making Test A and B (DKEFS) four months after completed working memory training. TMT A 0-250 seconds less time indicate better performance TMT B 0-350 seconds less time indicate better performance Shift cost (TMTB-TMTA): 0-200 seconds, less shift cost indicate better performance

    Time frame: 16 weeks (posttest 1-posttest 2)

  27. Executive function total score

    Improvement calculated composite score based on z-score((raw test score-mean of group)/standard deviation of group) of Stroop test and Trail Making Test A and B after 30 sessions of working memory training higher score indicate better performance. Range -4 to 4. (z score(-TMTB-TMTA)+z score(-inhibition cost))/2

    Time frame: 6-8 weeks (pretest-posttest 1)

  28. Executive function total score

    Maintenance of calculated z-score ((raw test score-mean of group)/standard deviation of group) of Stroop test and Trail Making Test A and B after 30 sessions of working memory training higher score indicate better performance. Range -4 to 4. (z score(-TMTB-TMTA)+z score(-inhibition cost))/2

    Time frame: 16 weeks (posttest 1-posttest 2)

  29. Transfer task subjective cognitive complaints

    Improvement on subjective memory complaints measured by Prospective retrospective memory questionaire after 30 sessions of working memory training. total score: 16-80 higher scores indicate more cognitive complaints prospective score: 0-100 higher scores indicate more cognitive complaints retrospective score: 0-100 higher scores indicate more cognitive complaints short term score: 0-100 higher scores indicate more cognitive complaints long term score: 0-100 higher scores indicate more cognitive complaints self cued score: 0-100 higher scores indicate more cognitive complaints environmentally cued: 0-100 higher scores indicate more cognitive complaints

    Time frame: 6-8 weeks (pretest-posttest 1)

  30. Transfer task subjective cognitive complaints

    Maintenance of subjective memory complaints measured by Prospective retrospective memory questionaire four months after completed working memory training.total score: 16-80 higher scores indicate more cognitive complaints prospective score: 0-100 higher scores indicate more cognitive complaints retrospective score: 0-100 higher scores indicate more cognitive complaints short term score: 0-100 higher scores indicate more cognitive complaints long term score: 0-100 higher scores indicate more cognitive complaints self cued score: 0-100 higher scores indicate more cognitive complaints environmentally cued: 0-100 higher scores indicate more cognitive complaints

    Time frame: 16 weeks (posttest 1-posttest 2)

Other outcomes

  1. Hospital Anxiety Depression scale (Depression and anxiety)

    Severity of depression and anxiety symptoms measured by Hospital Anxiety Depression scale Anxiety score: 0-21 higher score indicate more anxiety Depression score: 0-21 higher score indicate more depression

    Time frame: 6-8 weeks (pretest- posttest 1) 16 weeks (posttest 1 - posttest 2)

  2. Short Form Health Survey sf-36 (Health status)

    Health status measured by the Short Form Health Survey (sf-36) physical functioning score: 0-100 higher scores indicate less problems role limitations score: 0-100 higher scores indicate less problems energy fatigue score: 0-100 higher scores indicate less problems emotional well being score: 0-100 higher scores indicate less problems social functioning score: 0-100 higher scores indicate less problems pain score: 0-100 higher scores indicate less problems general health: 0-100 higher scores indicate less problems

    Time frame: 6-8 weeks (pretest- posttest 1) 16 weeks (posttest 1 - posttest 2)

  3. Short version of the Karolinska Sleep Questionnaire (Sleep status)

    Sleep status measured by the Short version of the Karolinska Sleep Questionnaire total score: 5-30 higher scores indicate better sleep

    Time frame: 6-8 weeks (pretest- posttest 1) 16 weeks (posttest 1 - posttest 2)

  4. Parkinson's Disease Questionnaire PDQ-39 (Function and well being)

    Function and well being measured by Parkinson's Disease Questionnaire-39 (PDQ39) Mobility score: 0-100 higher scores indicate more problems Activity of Daily Living score: 0-100 higher scores indicate more problems Emotional well being score: 0-100 higher scores indicate more problems Stigma score: 0-100 higher scores indicate more problems Social support score: 0-100 higher scores indicate more problems Cognition score: 0-100 higher scores indicate more problems Communication score: 0-100 higher scores indicate more problems Bodily discomfort score: 0-100 higher scores indicate more problems Summary index: 0-100 higher scores indicate more problems

    Time frame: 6-8 weeks (pretest- posttest 1) 16 weeks (posttest 1 - posttest 2)

  5. Urgency, Premeditation, Perseverance and Sensation Seeking Questionnaire UPPS (Impulsivity and risk taking)

    Impulsivity and risk taking measured by Urgency, Premeditation, Perseverance and Sensation Seeking Questionnaire (UPPS) Urgency score: 0-100 higher score indicate more urgency Premeditation score:0-100 higher score indicate less premeditation Perseverance score: 0-100 higher score indicate less perseverance Sensation seeking score: 0-100 higher score indicate more sensation seeking.

    Time frame: 6-8 weeks (pretest- posttest 1) 16 weeks (posttest 1 - posttest 2)

  6. Balloon Analogue Risk Taking Task BART (Impulsivity and risk taking)

    Impulsivity and risk taking measured by the Balloon Analogue Risk Taking Task (BART). Number of explosions: 0-30

    Time frame: 6-8 weeks (pretest- posttest 1) 16 weeks (posttest 1 - posttest 2)

  7. Checklist Individual Strength Questionnaire CIS (Fatigue)

    Fatigue measured by Checklist Individual Strength Questionnaire (CIS) after 30 sessions of working memory training. total score: 20-140

    Time frame: 6-8 weeks (pretest- posttest 1) 16 weeks (posttest 1 - posttest 2)

  8. Adherence (Task engagement)

    Task engagement is measured by self assessed motivation to training and ability to stay focused during training measured before and after each training session.

    Time frame: 6-8 weeks (during training)

  9. Compliance (Finishing training within time frame)

    Compliance is measured by number of participants finishing the training within time frame, 6-8 weeks.

    Time frame: 6-8 weeks (during training)

  10. Age

    Demographic characteristic: age at baseline

    Time frame: before training (pretest)

  11. sex

    Demographic characteristic: sex

    Time frame: before training (pretest)

  12. Educational level

    Demographic characteristic: educational level

    Time frame: before training (pretest)

  13. Disease duration

    Demographic characteristic: disease duration

    Time frame: before training (pretest)

  14. Disease stage

    Disease characteristic: disease stage (Hoehn and Yahr stage) Range 0-4

    Time frame: before training (pretest)

  15. Levodopa Equivalent Dose (Medication for Parkinson's Disease)

    Medication use measured by Levodopa Equivalent Dose

    Time frame: 6-8 weeks (pretest- posttest 1) 16 weeks (posttest 1 - posttest 2)

  16. Unified Parkinson's Disease Rating Scale (Motor symptoms)

    Motor symptoms assessed by the Unified Parkinson's Disease Rating Scale part 3 Total score:0-108 (higher scores indicate more motor symptoms)

    Time frame: before training (pretest)

  17. Mini Mental State Examination (Global cognitive function)

    Global cognitive function measured by Mini Mental State Examination (MMSE) Total score: 24-30 (patients with lower scores is not included), lower scores indicate worse performance.

    Time frame: before training (pretest)

  18. Side (left or right) most affected of Parkinson's Disease symptoms

    Disease characteristic: Most affected and starting side (Parkinsons symptoms)

    Time frame: before training (pretest)

  19. Swedish vocabulary test SRB (Verbal ability)

    Verbal ability measured by Swedish vocabulary test (SRB). total score: 0-30 higher scores indicate better performance

    Time frame: before training (pretest)

  20. Incidence of Treatment-Emergent Adverse Events (Safety and tolerability)

    All adverse events connected to training reported from participants and/or family members throughout the training period and after training are registered.

    Time frame: 6-8 weeks (during training and at post test)

07

Study locations

1 of 1 sites recruiting
  • Umeå University department of psychology
    Umeå, Västerbotten County 90187, Sweden
    Recruiting
08

References and documents

Publications

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  • Unsworth N, Engle RW. The nature of individual differences in working memory capacity: active maintenance in primary memory and controlled search from secondary memory. Psychol Rev. 2007 Jan;114(1):104-32. doi: 10.1037/0033-295X.114.1.104. PubMed 17227183 ↗
  • Gabrieli JDE, Singh J, Stebbins GT, & Goetz CG. Reduced working memory span in Parkinson's disease: Evidence for the role of frontostriatal system in working and strategic memory. Neuropsychology, 10(3): 322-332,1996.
  • McCabe DP, Roediger HL, McDaniel MA, Balota DA, Hambrick DZ. The relationship between working memory capacity and executive functioning: evidence for a common executive attention construct. Neuropsychology. 2010 Mar;24(2):222-243. doi: 10.1037/a0017619. PubMed 20230116 ↗
  • Chein JM, Morrison AB. Expanding the mind's workspace: training and transfer effects with a complex working memory span task. Psychon Bull Rev. 2010 Apr;17(2):193-9. doi: 10.3758/PBR.17.2.193. PubMed 20382919 ↗
  • Dahlin E, Neely AS, Larsson A, Backman L, Nyberg L. Transfer of learning after updating training mediated by the striatum. Science. 2008 Jun 13;320(5882):1510-2. doi: 10.1126/science.1155466. PubMed 18556560 ↗
  • Backman L, Nyberg L, Soveri A, Johansson J, Andersson M, Dahlin E, Neely AS, Virta J, Laine M, Rinne JO. Effects of working-memory training on striatal dopamine release. Science. 2011 Aug 5;333(6043):718. doi: 10.1126/science.1204978. PubMed 21817043 ↗
  • Dahlin E, Nyberg L, Backman L, Neely AS. Plasticity of executive functioning in young and older adults: immediate training gains, transfer, and long-term maintenance. Psychol Aging. 2008 Dec;23(4):720-30. doi: 10.1037/a0014296. PubMed 19140643 ↗
  • Backman L, Waris O, Johansson J, Andersson M, Rinne JO, Alakurtti K, Soveri A, Laine M, Nyberg L. Increased dopamine release after working-memory updating training: Neurochemical correlates of transfer. Sci Rep. 2017 Aug 2;7(1):7160. doi: 10.1038/s41598-017-07577-y. PubMed 28769095 ↗
  • El Haffaf LM, Domellof ME, Ronat L, Monchi O, Walton L, Backstrom D, Boraxbekk CJ, Forsgren L, Nyberg L, Neely AS, Johansson J. Latent-profile analysis of sleep disturbances, cognitive performance and neuropsychiatric symptoms reveals subtypes of Parkinson's disease. Front Neurol. 2026 Mar 4;17:1765246. doi: 10.3389/fneur.2026.1765246. eCollection 2026. PubMed 41859407 ↗
  • Walton L, Neely AS, Backstrom D, Eriksson Domellof M. The experience of process-based cognitive training in people with Parkinson's disease: a route to transfer to everyday life. Neuropsychol Rehabil. 2026 Feb 10:1-20. doi: 10.1080/09602011.2026.2613961. Online ahead of print. PubMed 41667390 ↗
  • Domellof ME, Walton L, Boraxbekk CJ, Backstrom D, Josefsson M, Forsgren L, Stigsdotter Neely A. Evaluating a frontostriatal working-memory updating-training paradigm in Parkinson's disease: the iPARK trial, a double-blinded randomized controlled trial. BMC Neurol. 2020 Sep 7;20(1):337. doi: 10.1186/s12883-020-01893-z. PubMed 32894075 ↗
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Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on Jun 22, 2021, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
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Registry details

Key details

Study ID
NCT03680170
Lead sponsor
Umeå University
Collaborators
Karlstad University
Responsible party
Anna Stigsdotter Neely (Professor, Umeå University) — Principal investigator
First posted
Sep 21, 2018
Start date
Feb 1, 2017
Primary completion
Feb 1, 2023 (estimated)
Completion
Feb 1, 2023 (estimated)
Last update
Jun 22, 2021

Study contacts

Anna S Neely, prof
Contact
anna.neely@kau.se
+46547001545
Magdalena E Domellöf, Phd
Contact
magdalena.domellof@umu.se
+4690786 70 22
Anna S Neely, Prof
principal investigator · Karlstad University

Oversight

Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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