By: Andrew Siderowf, MD
University of Pennsylvania Parkinson's Disease and Movement Disorders Center
The term “impulse control disorders” (ICDs) describes a group of behaviors that may affect Parkinson’s patients, particularly those patients receiving dopaminergic treatment. The main ICDs are: excessive or pathological gambling, binge eating, compulsive shopping and compulsive sexual behavior. Patients may have more subtle ICDs including project-orientedness, which is compulsively working on projects (like home improvements) without necessarily finishing them, or compulsive internet searching. These behaviors, which are sometimes called “hobbyism”, are less socially inappropriate, and may be mistaken for healthy industriousness by clinicians that are not familiar with ICDs.
Other behaviors that are related to ICDs include purposelessly taking apart gadgets like clocks or electronics, called “punding”, and aimlessly walking or driving around for long periods of time. This latter behavior is sometimes termed “walkabout”.
ICDs were initially described in PD patients in 2003, but probably were under-recognized for a number of years prior to that time. Treatment with dopaminergic medications is the main risk factor for ICDs. In particular, treatment with dopamine agonists is a major risk factor for ICDs. Approximately 15% of patients treated with a dopamine agonist could have an ICD problem, compared to about 5% who are not receiving a dopamine agonist. All medications in this class – pergolide (now off market due to cardiac side effects), pramipexole and ropinirole – are about equally associated with ICDs. Recently diagnosed PD patients who are not on any medication have a risk for ICDs that appears to be similar to the general population. Patients receiving other treatments for PD including levodopa or deep brain stimulation have a somewhat increased risk, but not to the same extent as patients treated with dopamine agonists.
It is important to note that dopamine agonist medications can still be used safely in PD patients and have been demonstrated to be effective in reducing motor symptoms like tremor, rigidity and bradykinesia. ICD behaviors resolve almost immediately once the relevant medication has been discontinued.
Other risk factors for ICDs include younger age, smoking and a family history of gambling problems. Neuropsychological factors associated with ICDs include greater depression and axiety, obsessive-compulsive symptoms, higher novelty seeking and impulsivity. More severe motor impairment has also been linked to greater risk for ICDs. In spite of these associations, one of the hallmarks of ICDs is that they often occur in people who have shown no inclination to impulsive or socially inappropriate behavior in the past, and reflect an unmistakable change from a patient’s normal personality.
ICDs can have substantial financial and social consequences. Many patients act on their impulses in secret because they are aware that the behaviors are socially inappropriate. Patients are also unlikely to connect behaviors to their medical treatment unless they have been made aware of the association. For these two reasons, patients are unlikely to spontaneously report their ICD behaviors to their doctor. It is essential that clinicians are pro-active in educating PD patients about ICDs, particularly those who are about to begin treatment with dopamine agonist medications. It is also essential to probe specifically for the presence of ICDs at follow-up clinic visits. Patients should also report any unusual behaviors or urges to their physicians, because they could be linked to treatment. By taking these relatively simple steps, the vast majority of potentially damaging ICDs can be avoided.
Andrew Siderowf, MD, is the Medical Director of the NPF Center of Excellence at the University of Pennsylvania Parkinson's Disease and Movement Disorders Center.