Exercise and Cognitive Training in Parkinson's Disease

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.

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