Impulse Control Disorders

Impulse control disorders (ICDs) are behavioral disturbances in which a person fails to resist the drive to behave in ways that result in distress or impaired social and occupational functioning. In Parkinson’s disease (PD), ICDs are closely related to use of dopaminergic medications, and most commonly include pathological gambling, excessive spending, hypersexuality and over-eating. Individuals can have more than one ICD concurrently.

The prevalence of ICDs in PD is not precisely known. One recent study conducted at Johns Hopkins Hospital found that ICDs were present in 9% of patients in a research study involving PD patients younger than 65. Studies looking at rates of specific ICDs in clinic populations found that pathological gambling and hypersexuality, individually, affected 2-5% of patients.

There are a number of similarities among the different types of ICDs. First, it is important to note that gambling, sex and shopping, the most frequently reported ICDs, are all within the normal repertoire of human behaviors. It is the unusual extent and frequency of ICD behaviors that make them maladaptive and detrimental. Often, the ICD behaviors are continued despite the knowledge that performing them will lead to bad outcomes and adverse consequences. This point helps differentiate ICDs as a disorder of behavior as opposed to a disorder of cognition. With a disorder of cognition, a person may be unable to tell right from wrong. By contrast, in a behavioral disorder, the person can distinguish right from wrong but is unable to conform his or her actions to those standards. In the example of pathological gambling, the individual knows that spending their retirement savings on gambling is wrong, but is unable to resist the urge to do so.

Pathological Gambling

Psychiatrists define pathological gambling as persistent and recurrent maladaptive gambling behavior that the patient has made repeated unsuccessful efforts to control. Affected patients may lie to family members or others to conceal the extent of involvement with gambling.

Hypersexuality and PD

Hypersexual behaviors vary from person to person, but represent a deviation from the individual’s usual sexual activity in frequency, intensity or context. Hypersexuality can start as intrusive thoughts or urges and trend into inappropriate remarks or acts. Some patients may begin to use pornography, patronize prostitutes, or develop paraphilias. Paraphilias involve recurrent, intense sexually arousing fantasies, urges or behaviors, including activities such as sado-masochism, exhibitionism or frotteurism (the practice of achieving sexual stimulation or orgasm by touching and rubbing against a person without the person’s consent and usually in a public place). The altered sexual activity can occur within an established context (e.g., increased demand for sex with one’s spouse, perhaps involving new types of sexual behaviors) or it may devolve into indiscriminate sexual activity in random contexts.

Excessive shopping and other impulse control disorders (i.e. skin picking) have also been described in patients with Parkinson’s Disease and share common features of being behaviors that are distressing and difficult to resist. Examples of excessive shopping might include the purchase of 15 art-deco lamps for a modest two-bedroom house or clothes that one never wears or shopping for mundane items with abnormal frequency (much beyond what is needed). One patient frequently purchased items at a local warehouse store, e.g., 25 fire extinguishers, and would later justify such purchases by saying they were going to be used as employee gifts.

Are impulsive behaviors a side effect of Parkinson’s medication?

Impulsive behaviors that occur in patients with PD can be difficult to distinguish from other psychiatric disturbances that can also occur in PD. Manic or hypomanic disturbances are characterized by persistently elevated, grandiose or irritable mood states and can involve impulsive over-activity, including inappropriate spending, sexual activity, or gambling. However, with ICDs, the overactive behavior is highly focused and driven. In general, ICDs in PD patients tend to be distinct from manic or hypomanic states. ICDs are also not part of an obsessive-compulsive disorder, in which repetitive unwanted thoughts (obsessions) compel a person to perform ritualistic behaviors (compulsions) to reduce anxiety. Instead, impulsive behaviors are often motivated by pleasure, gratification or some other reward.

In humans, the brain regions involved in reward are largely controlled by dopamine, the same neurotransmitter involved in the movement centers of the brain.  ICDs in PD appear in large part to be induced by dopaminergic medications, via disturbance of the reward system. Medical literature supports a strong association between impulse control disorders and anti-parkinsonian medication, especially the dopamine agonists. In fact, ICDs have been shown to develop in patients receiving dopamine agonists for non-PD causes such as restless leg syndrome, fibromyalgia and pituitary adenomas. Genetic differences in dopamine receptors and metabolism most likely play a role in determining which patients are at greatest risk of ICDs.

Variables associated with ICDs include, younger age, male sex and personal or family history of alcoholism or gambling. Symptoms of depression, irritability, and appetite disturbances may also be associated with the presence of these behaviors. All patients however should be screened for ICD symptoms. It is also important for care partners to communicate these symptoms to the physician if the patient does not want to reveal that these behaviors are problematic. Like many unwanted side effects of medications, ICDs often start when dopaminergic medications are increased or when a second dopaminergic drug is added. Because of that, it is important for the physician to continue to ask for a patient and/or care partner report about ICDs at follow-up visits, especially after dose changes. The recognition by clinicians and patients that there is a relationship between PD, anti-parkinsonian medications, and ICDs will help improve detection of these behaviors, which are often hidden out of shame.

The treatment of ICDs in PD is to lower dopaminergic medications. Often this is challenging because the medications are needed to treat the movement disorder aspect of PD. Stopping PD medications altogether in order to treat an ICD is usually not practical. However, stopping or reducing the dose of the suspected agent often helps.

Particularly when lowering or stopping a dopamine agonist, care has to be taken not to precipitate a withdrawal syndrome. Lowering a dopamine agonist slowly is therefore essential. Symptoms of withdrawal could include irritability, depression and even suicidality. Patients and care partners should therefore be warned about the possibility of withdrawal when the dose of a dopamine agonist is lowered.

When a dopamine agonist is suspected of contributing to an ICD, the patient can be switched to levodopa. If the agonist was added to levodopa to improve movement, options include using a higher dose of levodopa or using other medicines, such as entacapone, to prolong the effectiveness of the levodopa dose. Many patients report rapid cessation of ICD symptoms and behaviors after they stop dopamine agonists. However, if motor symptoms are not adequately controlled, patients may be tempted to resume the dopamine agonist, without informing others, and the behaviors can return. In some cases, it is unclear whether the offending agent, most often a dopamine agonist, is mostly giving patients an enhanced sense of well-being (the reward) or if the agonist actually provides a greater sense of control over motor symptoms. When stopping the offending PD medication is not effective or not an option, we have frequently added low dose quetiapine, an antipsychotic, and this often has a clear effect on helping the patient resist impulses. Unfortunately, not every patient can tolerate quetiapine, which can cause sedation and other side effects.

Regardless of the pharmacologic intervention used to treat ICDs, behavioral measures are also an important part of management. Behavioral measures are especially important because they can prevent some of the consequences of such behaviors. Behavioral interventions include taking away credit and bank cards, and limiting account access in the case of gambling. Restricting use of the Internet and video player can help in some cases for hypersexuality. For some ICDs 12-step gambling groups can also be helpful.

Once an impulsive behavior is recognized, the most important and first step a patient or caregiver should take is to inform the patient’s physician. Stopping or changing medication doses without guidance can produce unwanted side effects in other aspects of functioning. It is also important to confirm that the impulsive behaviors are not occurring in the context of an affective disorder (i.e. bipolar disorder) which if left untreated could lead to further impairment of functioning.

by Greg Pontone, MD (revised by APDA Nov 2018)


Dr. Pontone is a psychiatrist at Johns Hopkins University School of Medicine where he is a clinical research fellow in Geriatric Psychiatry and Movement Disorders. Dr. Pontone’s research focuses on the neuropsychiatric aspects of Parkinson’s Disease and other movement disorders.

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