Exogenous Effects of Standard Medical Care (Dopamine) on Motor Learning of an Upper Limb Task in Parkinson Disease

Not Applicable

Completed

Brief Summary: The study determines whether standard medical care (dopamine) affects learning and retention of an upper limb feeding task in people with Parkinson's disease (PD) and whether training on the feeding task generalises to performance on an untrained upper limb buttoning task. Half the participants will train on the feeding task after they have taken their first dose of dopamine for the day (i.e. "on" medication state), while the other half will train on the same feeding task before taking their first daily dose of dopamine (i.e. "off" medication state).

Detailed Description: Parkinson disease (PD) is an age related neurodegenerative disorder with symptomatic declines in motor function due to a loss of dopaminergic neurons within the basal ganglia.

Ironically, treatment with exogenous dopamine-replacement medication (e.g. levodopa) may have positive effects on existing motor skills such as handwriting or walking, but may have detrimental effects on the learning of motor skills necessary for effective rehabilitation.

Although dopamine medications are routinely prescribed to replace lost dopamine in the sensorimotor areas of the striatum, they may actually be "overdosing" the associative striatum, a candidate neuroanatomical correlate for motor learning. To date, however, this 'overdose' hypothesis has not been widely tested, given that few studies of motor learning in PD have reported or controlled for whether individuals were tested "on" or "off" their dopamine replacement medication.

Recruitment & Eligibility

Inclusion Criteria

Idiopathic Parkinson's disease confirmed by neurologist
Hoehn and Yahr stages 1 to 3
On a stable dose of antiparkinsonian medication for the past month and will continue on this regime for at least another subsequent month
Walks unaided

Exclusion Criteria

Arm && Interventions

Group	Intervention	Description
Training "off" medication	Upper limb feeding training	Participants will train on the upper limb feeding task before taking their first daily dose of standard dopamine medication for Parkinson's disease, i.e. while "off" dopamine replacement medication
Training "on" medication	Upper limb feeding training	Participants will train on the upper limb feeding task after taking their first daily dose of standard dopamine medication for Parkinson's disease, i.e. while "on" dopamine replacement medication

Primary Outcome Measures

Name	Time	Method
Task performance (response time) at initial retention, adjusted for baseline (first trial of acquisition on Day 3)	Day 8 (i.e. 48 hours after the last block of training)

Secondary Outcome Measures

Name	Time	Method
Delayed decrement (difference in response time between delayed retention and the last trial of acquisition) in task performance, adjusted for baseline (first trial of acquisition)	Day 5, Day 15 (i.e. 9 hours after the last block of training)
Immediate decrement (difference in response time between initial retention and the last trial of acquisition) in task performance, adjusted for baseline (first trial of acquisition)	Day 5, Day 8 (i.e. 48 hours after the last block of training)
Buttoning task score	Day 15 (i.e. 9 days after the last block of training)	Time taken to complete the Buttoning task at delayed retention, adjusted for baseline (Buttoning task score at baseline, i.e. 3 days prior to the first block of training)
Rate of improvement	Day 1 through Day 3	Rate of improvement (c) modelled on the exponential decay function: y = a + be(exp\[-x/c\]), where a is the final trial time value that the exponential decay function approaches (ie, asymptote), b is the scale of the learning from the first trial time to the value a, x is the trial number, 1/c is the number of trials needed to obtain asymptote (ie, 1 - e-1).
Nine hole peg test score	Day 15 (i.e. 9 days after the last block of training)	Time taken to complete the Nine Hole Peg Test at delayed retention, adjusted for baseline (Nine Hole Peg Test score at baseline, i.e. 3 days prior to the first block of training)