Dopaminergic Enhancement of Learning and Memory in Aphasia

Our prior work shows that d-amphetamine and the dopamine precursor levodopa markedly improve word learning success in healthy subjects. In this randomized, placebo-controlled, double-blind clinical trial, we probe whether daily administration of levodopa, coupled with several hours of language training every day, will significantly improve naming abilities in patients with aphasia as compared to placebo administration. We furthermore examine with magnetic resonance imaging which brain regions need to be functionally intact for a dopaminergic improvement of language therapy.

Inclusion criteria

for patients with aphasia:

• Unilateral cerebrovascular accident (stroke) in the territory of the arteria media
• Time post onset: > 6 months
• Aphasia with anomia
• Age between 18-75 years
• Premorbid right-handedness
• Primary language: German

Exclusion criteria

for patients and healthy controls:

• Known allergy to levodopa or tartrazine
• History of medication/drug abuse
• Acute nicotine withdrawal or > 15 cigarettes per day
• > 6 cups/glasses of coffee, caffeine drinks or energy drinks per day
• > 50 grams of alcohol per day
• Severe hypertonia (systole >180 mm Hg)
• Severe arteriosclerosis
• Diabetes, asthma, or glaucoma
• Severe hearing disability
• Evidence for severe hippocampal damage
• Premorbid depression or psychosis
• Medication with dopamine agonists or antagonists
• Parkinsonian symptoms
• Changes in anticonvulsive medication during the week prior to study enrollment