Impulsive and compulsive behaviour is related to dopamine levels in the brain. Dopamine is the chemical messenger in the brain that is primarily affected in Parkinson’s. As well as helping to control movement, balance and walking, dopamine also plays a big role in the part of the brain that controls reward and motivation. This is important, as people affected by impulsive and compulsive behaviour are driven or motivated to do something that gives them an instant reward. Some research suggests it is the anticipation of reward that is the driving factor, rather than the reward itself. For example the act of gambling and a potential win is more exciting than the win itself, which is why the behaviour is repeated.

Certain medications are thought to be linked to compulsive and impulsive behaviour, in particular dopamine agonists and, in some cases, levodopa. It is estimated that 17% of people taking dopamine agonists experience some degree of compulsive or impulsive behaviour whilst approximately 7% of people taking levodopa and other types of medication are affected¹. The mechanism between medication and changes in behaviour is not yet clear and is likely to vary as individuals each respond differently to a particular medication. However, stimulation of D³ receptor sites, as witnessed in other psychiatric disorders, might be one explanation as its involvement in mediating the incentive motivational effects of other drugs is recognised.

A 2009 study² found that over 18% of participants taking dopamine agonists developed compulsive gambling or hypersexuality. Those who were not taking these medications or who had only low doses of agonists, or took carbidopa/levodopa alone, did not develop this behaviour. To confirm the link between dopamine agonists and compulsive behaviour, the study also found that once dopamine agonists were either stopped or doses reduced, the gambling and hypersexuality also reduced.

It is important to emphasise that not everyone will experience unwanted behaviour. This is still relatively uncommon in Parkinson’s and you should continue taking your medication as prescribed. As always, it is important to monitor any change in behaviour when medication is altered or prescribed, so that adjustments can be made if necessary.

In some cases, changes in behaviour can be positive too, such as a renewed interest in a hobby or sex. In addition, some behaviour can be managed, for example limiting the amount of money available for someone to gamble with. Nevertheless any change should be reported to your nurse or doctor.

Factors that are thought to make a person more likely to develop compulsive or impulsive behaviour include: young onset of Parkinson’s, a history of depression, a family history of drug or alcohol abuse, being male, single or living alone.

References:

1. ‘Impulse Control Disorders in Parkinson Disease: A Cross-Sectional Study of 3090 Patients’ Weintraub, D, Koester, J and Potenza, M et al (2010), Arch Neurol; 67(5):589–595 - view abstract
2. Frequency of New-Onset Pathologic Compulsive Gambling or Hypersexuality After Drug Treatment of Idiopathic Parkinson Disease - Michael Bostwick, Kathleen A. Hecksel, Susanna R. Stevens, James H. Bower and J. Eric Ahlskog. Mayo Clinic Proceedings April 2009 vol. 84 no. 4:310-31 - view abstract. 

The most common types of behaviour in Parkinson’s are:

• pathological or addictive gambling – an inability to resist the temptation to gamble, even though the person realises the destructive impact this may have on finances and family. It is estimated that only around 8% of people with Parkinson’s show this type of behaviour, but as gambling has become much more widely available, for example via the Internet, it is thought that many more people are affected.
• hypersexuality – a preoccupation with sexual thoughts and feelings, sometimes accompanied by inappropriate sexual behaviour and increased demands for sexual activity. Sexual impulses may become intense and spontaneous which can harm relationships and can cause considerable distress. Sometimes this is accompanied by hallucinations or delusions, perhaps wrongly thinking that a partner is having an affair, for example. It is thought that around 8% of people with Parkinson’s experience hypersexual behaviour.
• compulsive or binge eating – a person may eat large quantities of food in a short period as they are unable to control their appetite. Sometimes the person will eat alone as they are embarrassed by their behaviour and may feel guilty at consuming such large amounts of food. Unsurprisingly this can lead to weight gain.
• compulsive shopping - a compulsive shopper will be unable to resist the impulse to shop and buy, even though purchases are usually unnecessary and often unaffordable. This can strain finances and relationships in the same way that gambling can. Internet shopping makes this easier.
• punding – this term refers to the carrying out of repetitive, aimless actions, often neglecting personal hygiene, sleep and daily routines in pursuit of relatively unimportant tasks. Behaviour becomes stereotyped, with an intense and repetitive preoccupation with actions such as examining, sorting and arranging items or equipment, or perhaps being obsessed with grooming or engaging in meaningless monologues. This can lead to social and relationship difficulties and sometimes sleep deprivation, all resulting in reduced quality of life.
• addiction to Parkinson’s medications - some people experience an addiction to excessive amounts of Parkinson’s medications, also known as dopamine dysregulation syndrome, even though this can produce unwanted side effects such as severe dyskinesia (involuntary movement) or other movement difficulties. Once addicted, a person may feel withdrawal symptoms if the medication becomes unavailable and may become aggressive or try to hoard a medication.
  Some people who are switched to levodopa-based treatment after experiencing impulsive and compulsive behaviour on other medication may develop dopamine dysregulation syndrome. So it is important for treatment to be monitored.

The following terms are sometimes used to differentiate between the types of behaviour related to dopamine replacement medications:

• dopamine deficiency syndrome, in which immediate reward seeking behaviour emerges
• dopamine dependency syndrome, characterised by addictive behaviour
• dopamine dysregulation syndrome, characterised by both addictive behaviour and stereotyped behaviour (often known as punding)
• impulse control disorders, including compulsive gambling, eating, shopping and hypersexuality.

Because of the sensitive or private nature of some behaviour it is not easy for family or friends to discuss this with the individual. The person may feel embarrassed or uncomfortable discussing the problem so they may need reassurance that their behaviour does not reflect badly on them and that they can talk in confidence with a healthcare professional. 

The person may be unaware of their personality changes so it is very important that family and friends who observe unusual behavioural traits discuss this as soon as possible with their doctor or an appropriate healthcare professional. Although it can be difficult to tackle such sensitive issues, prompt action can usually find effective treatment. 

A trial and error approach may be needed as the higher doses of Parkinson’s medication required to control motor symptoms may be the cause of the compulsive behaviour. But reducing medication can mean motor symptoms are less well controlled.

Treatment may involve reducing the daily dose of Parkinson’s medication, or withdrawing dopamine agonists in favour of levodopa or another type of medication. Any changes should be made gradually to minimise the risk of side effects or withdrawal symptoms such as anxiety or depression. Continuous dopaminergic stimulation (CDS), using levodopa/carbidopa or apomorphine for example, has been found to be effective for a number of people.

Depression or other mental problems may increase the likelihood of unwanted behaviour emerging so it is also important to get a mental health assessment from a qualified professional. If appropriate, counselling may help or antidepressant medications may be prescribed, particularly if any hallucinations or paranoia are also present. A course of psychotherapy may also be successful in some instances.

Amantadine has also been assessed as a potential treatment for ICDs. Further research is needed to define more precisely how amantadine may influence the development and treatment of ICDs in Parkinson's.

Family and friends may often notice unusual behaviour that the individual is unaware of or tries to keep secret, unaware in many cases of the impact such behaviour can have on those around them. Some of the signs to look out for include:

• repetitive behaviour, constantly organising objects or collecting items
• putting on weight, eating large quantities of food in private or constant snacking
• shopping much more than usual and spending more on shopping
• being protective about finances
• being secretive
• changes in sexual behaviour
• more aggressive behaviour
• spending much more time on the Internet, including late at night
• taking more Parkinson’s medication than they should.

Family and friends can also help by controlling the opportunities for compulsive behaviour, perhaps by creating opportunities for other activities to divert attention, by blocking Internet gambling sites or by taking away credit and bank cards so cash flow is restricted.

Because compulsive behaviours often cause problems in family life and social adjustment, family therapy may be advised.

Content last reviewed: September 2018

We would like to thank Jane Mills (CNS in Parkinson’s at Princess Royal University Hospital. Kings Healthcare, Farnborough, UK) for her help in reviewing this information. 

Our thanks to Parkinson's UK for permission to use the following source(s) in compiling this information:

• Impulsive & compulsive behaviour in Parkinson’s.

• VIDEO: Angelo Antonini, EAN 2020 – Impulse control disorders in Parkinson's disease
• Impulsive and compulsive behaviour - a film by Parkinson's UK for people affected by Parkinson's

• An informative video produced by Norges Parkinsonforbund (The Norwegian Parkinson’s Disease Association) outlining the key facts and symptoms of Impulse Control Disorders

• Wait and you shall see: sexual delay discounting in hypersexual Parkinson’s disease

Articles from Parkinson's Life online magazine

• Are impulse control disorders the last Parkinson’s ‘taboo’?
• Norwegian Parkinson’s Association tackles impulse control disorders in new film