Exercise and Cognitive Training in Parkinson's Disease

This study compares the effects treadmill exercise, computerized cognitive training, or the combination of the two on executive function, dual-task performance, and performance on several Instrumental Activities of Daily Living (IADLs).

Parkinson's Disease (PD) is recognized as both a motor and nonmotor disorder. Gait and mobility impairments are often associated with a decline of cognitive function, particularly executive function (EF), among other non-motor signs. EF is a broad category of cognitive functions that is generally defined as those processes necessary for purposeful, goal-directed behavior and supervision of ongoing cognitive processes. Deficits in EF are frequently seen early in PD4 and progress with time, often resulting in disruption of daily activities. People with PD are often impaired in real life situations in which more than one activity needs to be performed at a time. Dual tasking (DT) is defined as the performance of two different tasks simultaneously, commonly a gait plus a cognitive task. This study investigates the interaction of motor (gait) and non-motor (cognitive) impairments in PD. Studies of DT suggest that reciprocal interactions exist between gait and mental functions that are fundamental to the performance of daily activities. Therefore, the model of DT encompasses 2 major areas of PD-related impairment in a single outcome measure that is highly correlated with daily function. Performance on DT generally results in degradation of gait and/or cognitive performance. The investigators' pilot study in 125 people with PD has shown significant DT interference producing a 22% decline in gait velocity. This demonstrates deterioration of gait performance when subjects allocate attention to the cognitive task. Importantly, deficits on DT correlates with in problems in daily function, especially instrumental activities of daily living (IADLs), and is associated with increased risk of falling and driving impairment. Similarly, the investigators' pilot data in patients with moderate stage PD shows that deficits in DT performance are associated with poor IADL performance. Although cognitive deficits contribute to disability in PD, there are no treatments that effectively address this problem, and no studies have systematically investigated the potential benefits of rehabilitation strategies to improve cognitive function and related disability in this population. Emerging evidence suggests the potential of physical exercise and cognitive training to improve cognitive function in healthy elderly and individuals with chronic neurologic conditions. A Cochrane meta-analysis on the cognitive effects of aerobic exercise in older adults has shown that improvement of peak VO2 levels by a mean of 14% (range 5-20%) was associated with improvement in cognitive function, particularly EF domains including speed of motor processing and attention. These are the same EF domains in which deficits commonly occur in PD. Pilot data from the investigators' Baltimore VA study show that the investigators can reproduce similar gains in cardiopulmonary fitness in PD, as reported in the Cochrane review, with a 3-month aerobic exercise program. The investigators' group has also reported improvement of selected EF domains (attention and speed of processing) following 2 months of aerobic exercise in stroke patients12. Cognitive training is another potential rehabilitation modality to improve cognitive function. Recent studies in numerous neurological conditions and healthy older adults show that cognitive training improves cognition, with EF most likely to respond among all cognitive domains. In this project, the investigators are comparing the effectiveness of a treadmill aerobic exercise program (TAEX) versus a cognitive training program (TCOG) versus the combination of TAEX + TCOG for improving EF, DT performance and IADLs in the investigators' sample of Veterans and others with PD. The investigators' fundamental hypothesis is that 3 months of combined TAEX+TCOG will be most effective in improving EF, DT performance, and IADLs, compared to either regimen alone.

Dual task tested functional and cognitive performance while walking and talking simultaneously. Walking spatial and temporal parameters were measured using the Gaitrite 24 foot gaitmat with existing hardware and software for analysis. Cycle time refers to the amount of time taken for a participant to complete a single stride. Lower scores indicate better outcomes. The range of scores for Cycle Time is: Pre (0.73-2.47), Post (0.72-1.45).

Dual task tested functional and cognitive performance while walking and talking simultaneously. Walking spatial and temporal parameters were measured using the Gaitrite 24 foot gaitmat with existing hardware and software for analysis. Velocity was calculated by dividing the distance by the time it takes to travel that same distance, with consideration for direction. Higher values represent better outcomes. The range of scores for this study was: Pre (36.4 - 269.4), Post (76.3 - 267.6).

2-Choice Reaction Time measures patients' ability to shift mental set. One of two stimuli are presented on the screen ("+ "or "*"). Subjects press a specified response button on the keyboard corresponding to the presented stimulus. Units are "Throughput", which reflects efficiency of performance by being based on both accuracy and speed. Throughput represents correct responses/ minute.

The Stroop is a measure of selective attention and cognitive flexibility in which the subject must inhibit a preponderant response. Subjects are asked to complete three parts under timed conditions: (1) reading words describing colors written in black-and-white, (2) naming those colors when printed as X's, (3) naming the ink color when words describing the colors are mismatched with the colors (suppressing verbal content). Stroop interference scores from condition 3 are t-scores and higher scores equate with better outcomes.

The Timed IADL involves the timing of performance of 5 tasks that mimic everyday instrumental activities of daily living: 1) finding a telephone number in the telephone directory, 2) counting out correct change from a group of coins, 3) finding then reading the ingredients on a food can label, 4) finding two food items in an array of food items (shopping), 5) finding then reading the directions on a medicine container. For each task there is a 2 minute time limit, with the exception of the telephone number task which has a limit of 3 mins. If the task is not completed within the time limit it is terminated. Error codes are assigned for each task. For the tasks completed with minor errors, a time penalty of 1 SD of those who completed the task is added to the completion time. Higher single item scores mean worse performance.The times for each of the tasks are transformed into Z scores which are then summed to form a composite score. Range for shopping item (0.61- 69.9 sec)

The Timed IADL for Shopping involved finding two food items in an array of food items. The task was timed in seconds and if completed with minor errors, a time penalty was added to the completion time. Higher scores/times meant worse performance. The range for shopping task completion was 0.61 to 69.9 seconds.

Inclusion Criteria: Parkinson's disease stage 1-3 Hoehn and Yahr Balance problems Exclusion Criteria: unstable medical illness unstable psychiatric illness exercising too much on own doing computerized memory training on own