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Patients often are in substantial debt before the problem is recognised
Parkinson's disease is common. It is estimated to affect around one in 200 people in the developed world (between six and 11 people per general practice in the United Kingdom).1 For many patients, care is shared between general practitioners, geriatricians, general physicians, and neurologists, often alongside specialist nurses. Motor symptoms and signs of Parkinson's disease are well recognised, yet the behavioural problems are less well known, particularly the recently described problems of pathological gambling and other addictive behaviours.2 3 4 5 6 7Pathological gambling is an impulse control disorder characterised by excessive gambling.8 The prevalence of pathological gambling in Parkinson's disease is about 3.4%, rising to 7.2% in patients taking dopamine agonists.6 In contrast, the lifetime prevalence of pathological gambling in the general population in the UK is 1%.9 It can be associated with the presence of other compulsive disorders such as the compulsive use of dopaminergic drugs,4 compulsive shopping, and hypersexuality.6 People who develop Parkinson's disease at a younger age are reported to have a higher risk of pathological gambling.5
Although the pathophysiology of pathological gambling in Parkinson's disease is not well understood, it may relate to aberrant dopaminergic stimulation.2 It is not clear which dopamine agonist precipitates the disorder, as all such agonists have been implicated.2 3 5 Patients taking both a dopamine agonist and levodopa are at increased risk,2 although those who take either a single dopamine agonist or levodopa can be affected.7
About 5.8 million people in the UK—one in 10 internet users—log on to internet gambling sites each month.10 This is expected to rise as more households connect to the internet11 and as the use of broadband increases. Many internet gambling companies actively lure gamblers with pop-ups to place free bets. This marketing technique is pervasive and can make it hard for vulnerable people to wean themselves off gambling.3
We have noted that our patients are often secretive about their gambling and may end up thousands of pounds in debt before the problem is realised. Patients and families often do not suspect drug treatment as the cause of pathological gambling and therefore do not mention it to the doctor. Better awareness of the problem among patients and carers, coupled with routine direct questioning by clinical staff about changes in behaviour and development of new compulsions and gambling, will help to identify the problem early.
Once recognised several strategies may help. Reducing or stopping dopamine agonists may be considered, as anecdotal evidence suggests this helps improve or stop the pathological gambling behaviour.2 3 If this results in deterioration of the motor state, then combinations of other drugs for treating Parkinson's disease may be tried, including levodopa, apomorphine, catechol-O-methyltransferase inhibitors (such as entacapone), and monoamine-oxidase-B inhibitors (such as selegiline). Cognitive behaviour therapy and serotonin selective reuptake inhibitors have been tried with variable success.12 Nalmefene (Revex), an opioid antagonist, was recently reported in a randomised controlled trial to be effective in pathological gambling.13 However, the lack of good quality clinical trials in pathological gambling that assess the long term impact of interventions means that patients need to be closely monitored for signs of relapse, by sensitive but direct questioning to patients and their families. Advice given by clinicians to the patient and family on practical ways to avoid the temptation to gamble (such as installing firewalls against internet pop-ups for internet gamblers,3 or tearing out the newspaper racing pages), together with support from family, friends, and carers to control finances may help resolve the problem.
Details of the UK's proposed regulations on the internet gambling industry are due to be announced shortly.11 The current debate on regulating gambling is relevant to this group of patients. This provides an ideal opportunity to deal with the problem through appropriate legislation to protect a small, though highly vulnerable, group in our society.
Competing interests: MJS has received financial support from GlaxoSmith Kline the manufacturers of ropinirole to attend several conferences; MJS acts as an adviser and is involved in clinical research trials for Schwarz Pharma, the manufacturer of rotigotine.
Provenance and peer review: Non-commissioned; externally peer reviewed.