A Novel Way of Measuring Dual-Task Interference: The Reliability and Construct Validity of the Dual-Task Effect Battery in Neurodegenerative Disease.

The Parkinson's and Alzheimer's data came from routine physical therapy records at one outpatient facility, so they may represent a selected clinical population. The healthy group was younger, and the groups differed in sex composition and racial composition. The study used one dual-task paradigm, walking with serial subtraction, so results may not apply to other daily dual-task demands. The instructions encouraged neutral prioritization, but they may still have changed how participants allocated attention. The task prioritization category was unreliable in the Parkinson's and Alzheimer's groups, and the attention allocation index was unreliable in the healthy group. The Parkinson's group had cognition largely within normal limits, so results may not apply to Parkinson's disease dementia. Falls were collected retrospectively, so the fall associations should be interpreted cautiously. Because the study was retrospective, some variables that could relate to the battery were not available. Diagnoses were made clinically, and disease stage may differ between individuals. The battery was tested for measurement properties, not for effects of treatment or rehabilitation.

The authors declared no conflict of interest. The paper's publication types list NIH extramural research support.

Do not read this as evidence that dual-task training improves walking or thinking. The study tested measurement properties, not a treatment effect. Do not use the battery to distinguish Parkinson's disease from Alzheimer's disease, because the two groups did not differ from each other.