Dual-Task Paradigms

Dual-task paradigms, in which an individual performs tasks separately and then concurrently, often demonstrate that people with neurodegenerative disorders experience more dual-task interference, defined as worse performance in the dual-task condition compared to the single-task condition.
Dual-task paradigms usually involve a motor task and a cognitive task, although other combinations exist. Motor tasks often assess an aspect of walking, such as gait speed, stride length or stride variability, or arm swing parameters such as amplitude, variability or asymmetry. Cognitive tests vary greatly, and include serial subtraction, memory tests (digit strings/word strings/short stories), semantic fluency, or phonemic fluency.

Dual-task performance as a predictor of walking activity post-stroke

Researchers assessed whether dual-task gait speed accounts for variance in daily ambulatory activity above what can be predicted with habitual (single task) gait speed in community-dwelling stroke survivors. They found single-task gait speed explained 15.3% of variance in daily ambulatory activity, and adding dual-task gait speed to the regression model increased the variance explained by an additional 20.6%.
Feld JA, Zukowski LA, Howard AG, Giuliani CA, Altmann LJP, Najafi B, Plummer P. Relationship Between Dual-Task Gait Speed and Walking Activity Poststroke. Stroke. 2018 May;49(5):1296-1298. PMCID:6034633

Dual-task performance as a pre-diagnostic marker in neuro-degenerative disease

Review of dual-task research in Alzheimer’s and Parkinson’s diseases
Researchers examined a range of studies that employed dual-task protocols in patients with Alzheimer’s or Parkinson’s disease. They also included studies with populations diagnosed with prodromal signs of these diseases. They noted an important methodological issue in trying to compare studies: a) a wide-range of cognitive tasks, e.g. working memory, episodic memory, serial subtraction and b) a variety of protocols for gait assessment, e.g. assigned pace, walking forward or backward, specified distances vs timed walks.
An emerging finding was that dual-task-related changes in stride time variability could be a motor signature of mild cognitive impairment (MCI), and thus be potentially used as a marker of cognitive decline before and during dementia, including Alzheimer’s. They stressed that their review included cross-sectional studies only, and that longitudinal studies could better delineate the continuum of gait profile changes in pre-clinical, prodromal and clinical stages of disease.
Belghali M, Chastan N, Cignetti F, Davenne D, Decker LM. Loss of gait control assessed by cognitive-motor dual-tasks: pros and cons in detecting people at risk of developing Alzheimer’s and Parkinson’s diseases. Geroscience. 2017;39(3):305-329. PMCID:5505895

Dual-task performance in cognitively normal older adults with and without an APOE ɛ4 allele
Researchers found APOE ε4 carriers tended to exhibit greater dual-task interference compared to low risk participants. Effect sizes for a group difference were larger when the cognitive task was executive function. Researchers concluded dual-task paradigms may reveal subtle changes in brain function in asymptomatic individuals at heightened risk of AD.
Whitson HE, Potter GG, Feld JA, Plassman BL, Reynolds K, Sloane R, Welsh-Bohmer KA. Dual-Task Gait and Alzheimer’s Disease Genetic Risk in Cognitively Normal Adults: A Pilot Study. J Alzheimers Dis. 2018;64(4):1137-1148. PMCID:6500574

Dual-task performance and correlations with biomarkers of neuro-degenerative disease

Researchers examined the relationship between performance in a Timed Up-and-Go dual-task (TUGdt) with Naming Animals and Months Backward as cognitive tasks and Alzheimer’s disease cerebrospinal fluid (CSF) biomarkers amyloid-β 42 (Aβ42), total tau (t-tau), and phosphorylated tau (p-tau). They found the number of correct words during TUGdt Naming Animals protocol correlated negatively to CSF t-tau and p-tau.
Åhman HB, Giedraitis V, Cedervall Y, Lennhed B, Berglund L, McKee K, Kilander L, Rosendahl E, Ingelsson M, Åberg AC. Dual-Task Performance and Neurodegeneration: Correlations Between Timed Up-and-Go Dual-Task Test Outcomes and Alzheimer’s Disease Cerebrospinal Fluid Biomarkers. J Alzheimers Dis. 2019;71(s1):S75-S83. PMCID:6839487

Intervention programs in neurological disease and changes in dual-task performance

Physical exercise in stroke patients
Researchers conducted a systematic search of the literature for trials/studies involving individuals with stroke and the effects of exercise and/or gait training interventions on dual-task gait speed. They found dual-task training tended to have a larger effect on dual-task gait speed than interventions without dual-task training.
Plummer P, Iyigün G. Effects of Physical Exercise Interventions on Dual-Task Gait Speed Following Stroke: A Systematic Review and Meta-Analysis. Arch Phys Med Rehabil. 2018 Dec;99(12):2548-2560. PMID:29738743 DOI link

Cognitive stimulation and physical exercise in older adults with mild dementia
Researchers examined the effect of a combined cognitive stimulation/physical exercise program on gait performance under single- and dual-task conditions in older adults with mild dementia. Gait measures included the Timed Up-and-Go and the 6-meter walk; cognitive measures included Animal Category and Serial Counting tasks. The combined program led to significant improvements in both cognitive performance and gait speed in the dual-task paradigm. No significant improvement in single-task gait speed was observed over time.
Tay L, Lim WS, Chan M, Ali N, Chong MS. A Combined Cognitive Stimulation and Physical Exercise Programme (MINDVital) in Early Dementia: Differential Effects on Single- and Dual-Task Gait Performance. Gerontology. 2016;62(6):604-610. PMID:15794703 DOI link

VR and traditional physical and cognitive training in older adults with MCI
Researchers examined the effects of VR-based physical and cognitive training or traditional physical and cognitive training on measures of executive function (Stroop Color and Word Test [SCWT] and trail making test), gait performance (gait speed, stride length, and cadence), and dual-task costs (DTCs). Dual-task functions included walking and serial subtraction (cognitive dual task) and walking and carrying a tray (motor dual task). Both groups showed significant improvements in the SCWT and single-task and motor dual-task gait performance measures. Only the VR group showed improvements in cognitive dual-task gait performance and the DTC of cadence.
Liao YY, Chen IH, Lin YJ, Chen Y, Hsu WC. Effects of Virtual Reality-Based Physical and Cognitive Training on Executive Function and Dual-Task Gait Performance in Older Adults With Mild Cognitive Impairment: A Randomized Control Trial. Front Aging Neurosci. 2019 Jul 16;11:162. PMCID:6646677

A pilot study of dual-task gait training in individuals with Parkinson’s disease (PD)
A pilot study examined the effects of cognitive and motor dual task gait training on dual task gait performance in PD. Individuals were assigned to cognitive dual task gait training (CDTT), motor dual task gait training (MDTT), or general gait training (control) group randomly. Researchers found cognitive dual-task gait training decreased double support time during cognitive dual-task walking, and motor dual-task gait training reduced gait variability during motor dual-task walking. In addition, the cognitive dual-task gait training improved the speed, stride length, and double support time under motor dual-task walking and single walking.
Yang YR, Cheng SJ, Lee YJ, Liu YC, Wang RY. Cognitive and motor dual task gait training exerted specific training effects on dual task gait performance in individuals with Parkinson’s disease: A randomized controlled pilot study. PLoS One. 2019 Jun 20;14(6):e0218180. PMCID:6586283