Pharmaceuticals
Dopamine Stimulants: Cognitive Enhancing Agents
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Persons who suffer brain injury often experience cognitive deficits in the areas of arousal, attention, language, memory, and reasoning. Studies have found deficient levels of brain chemicals called neurotransmitters that can affect cognitive function. The most commonly affected cognitive neurotransmitters appear to be dopamine, norepinephrine, and acetylcholine. Dopamine and norepinephrine affect arousal and attention, while dopamine is thought to also play a role in language function. Acetycholine is a neuro?transmitter involved in memory function.
Pharmacologic agents may boost levels of deficient transmitters or mimic transmitters where these natural chemicals are lacking. The two main classes of stimulant medications are classic stimulants and dopaminergic stimulants. The dopaminergic agents include l-dopa (Sinemet), Amantadine (Symmetrel), Bromocriptine (Parlodel), and others. L-dopa is taken up by the brain and converted directly into the natural transmitter, dopamine. Thus, if a dopamine deficiency exists, it is possible to correct this with l-dopa. Amantadine has a mixed mechanism working to stimulate the release of dopamine already in the brain and to mimic dopamine at its receptors. Bromocriptine can be used to mimic dopamine in areas where brain damage is so severe that dopamine cannot be normally produced. Additionally, classic stimulants, such as Ritalin (Methylphenidate), Dextroamphetamine (Adderall), or Modafinil (Provigil), can help to boost levels of dopamine and norepinephrine in the brain and can work together with l-dopa to increase brain dopamine levels.
Dopaminergic agents have been shown in small studies in select subjects to improve alertness or “arousal,” attention, concentration, language skills, memory, and hemi-neglect. (hemi-neglect, commonly referred to as “attention to one side of the environment” is a condition where persons neglect half of what they see in their environment. They may read only half a page of a newspaper, eat only on one side of their plate, or only shave on one side. Dopamine often helps correct this problem.) It presently is impossible to predict if cognition in any single individual will improve with these agents. Therefore, it may be reasonable after brain injury to consider trials of one or more of these stimulant agents.
The most common side effects of dopaminergic agents are nausea and vomiting. Rarely, these medications may produce abnormal involuntary movements, confusion, or psychosis. If these agents are used, patients should be closely monitored for side effects. Likewise, patients should be closely monitored for any significant improvements in cognitive function.
Alan M. Harben, MD, PhD is a Fellow of the American Academy of Physical Medicine and Rehabilitation and has completed doctoral training in the field of Biomechanics. He is Medical Director of the Restore Neurobehavioral Center located in Roswell, Georgia, a rehabilitation program for persons with behavioral disorders due to acquired brain injury. He also serves as the medical consultant for The Bridge, an adolescent psychiatric program located in Atlanta, Georgia. He is a past Chair of the Brain Injury Resource Foundation. His private practice in Roswell, Georgia specializes in neurological and musculoskeletal rehabilitation.