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Specific limb: A brief look at ‘restless legs syndrome’

Those that know me well often comment that I have a general inability to sit still and that I am a ‘fidget’. (This is not necessarily a bad thing and in fact there are some positives to fidgeting that I outlined in a previous blog on bad behaviours that are sometimes good for you). There is certainly some truth to the observation that I fidget but sometimes the fidgeting is out of my control. Every few weeks my right lower leg appears to take on a life of its own and I will get strange (uncomfortable) sensations (such as tingling, itching, and aching, and occasionally cramp-like feelings) that force me to move my right leg and foot around. It only happens when I am in a resting and relaxing state and usually lasts about 30 minutes (but can occasionally last much longer). On occasions it disrupts my work and sleep but I find that just getting up and moving around is sometimes enough to alleviate the uncomfortable feelings.

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A few years ago I Googled my ‘symptoms’ and was surprised to find that I am not the only person who appears to experience such effects and that there is a whole medical literature on what has been termed ‘restless legs syndrome’ although in my case it would be in a singular rather than plural form). I’ve had the condition for about 15 years now and it may be related to some of the medication I take for an unrelated chronic degenerative health condition that I have. According to the Wikipedia entry on restless legs syndrome (RLS):

“The first known medical description of RLS was by Sir Thomas Willis in 1672. Willis emphasized the sleep disruption and limb movements experienced by people with RLS…The term ‘fidgets in the legs’ has also been used as early as the early nineteenth century. Subsequently, other descriptions of RLS were published, including those by Francois Boissier de Sauvages (1763), Magnus Huss (1849), Theodur Wittmaack (1861), George Miller Beard (1880), Georges Gilles de la Tourette (1898), Hermann Oppenheim (1923) and Frederick Gerard Allison (1943). However, it was not until almost three centuries after Willis, in 1945, that Karl-Axel Ekbom (1907–1977) provided a detailed and comprehensive report of this condition in his doctoral thesis, Restless legs: clinical study of hitherto overlooked disease. Ekbom coined the term “restless legs” and continued work on this disorder throughout his career. He described the essential diagnostic symptoms, differential diagnosis from other conditions, prevalence, relation to anemia, and common occurrence during pregnancy. Ekbom’s work was largely ignored until it was rediscovered by Arthur S. Walters and Wayne A. Hening in the 1980s. Subsequent landmark publications include 1995 and 2003 papers, which revised and updated the diagnostic criteria”.

As well as being referred to as RLS, it is sometimes referred to as Willis-Ekbom Disease or Willis-Ekbom Syndrome. Since being ‘rediscovered’ in the 1980s, there have been a lot of scientific papers published on the phenomenon although many of these are medical case studies (I don’t think my own experiences are extreme enough or strong enough to appear in any medical textbook. The Wikipedia entry on RLS provides a good summary of what is known medically and empirically:

“Restless legs syndrome (RLS) is a disorder that causes a strong urge to move one’s legs. There is often an unpleasant feeling in the legs that improves somewhat with moving them. Occasionally the arms may also be affected. The feelings generally happen when at rest and therefore can make it hard to sleep. Due to the disturbance in sleep, people with RLS may have daytime sleepiness, low energy, irritability, and a depressed mood. Additionally, many have limb twitching during sleep. Risk factors for RLS include low iron levels, kidney failure, Parkinson’s disease, diabetes, rheumatoid arthritis, and pregnancy. A number of medications may also trigger the disorder including antidepressants, antipsychotics, antihistamines, and calcium channel blockers. There are two main types. One is early onset RLS which starts before age 45 [years], runs in families and worsens over time. The other is late onset RLS which begins after age 45 [years], starts suddenly, and does not worsen. Diagnosis is generally based on a person’s symptoms after ruling out other potential causes… Females are more commonly affected than males and it becomes more common with age…Some doctors express the view that the incidence of restless leg syndrome is exaggerated by manufacturers of drugs used to treat it. Others believe it is an under-recognized and undertreated disorder…An association has been observed between attention deficit hyperactivity disorder (ADHD) and RLS or periodic limb movement disorder. Both conditions appear to have links to dysfunctions related to the neurotransmitter dopamine, and common medications for both conditions among other systems, affect dopamine levels in the brain”.

According to a review by Dr. Richard Allen and Dr. Christopher Earley in the Journal of Clinical Neurophysiology, RLS affects 2.5-15% of the US population. In another review on sleep disorder in the journal American Family Physician, Dr. Kannan Ramar and Dr. Eric Olson reported that RLS is typically characterized by four essential features: These are:

“(1) the intense urge to move the legs, usually accompanied or caused by uncomfortable sensations (e.g., “creepy crawly,” aching) in the legs; (2) symptoms that begin or worsen during periods of rest or inactivity; (3) symptoms that are partially or totally relieved by movements such as walking or stretching; and (4) symptoms that are worse or only occur in the evening or at night”.

Various online articles and papers report a variety of potential treatments based on the notion that RLS might be caused by a dopamine imbalance in the body. Some medics advise a regular sleep routine (such as that advised for those with insomnia), and cutting out the drinking of alcohol and the smoking of cigarettes. Pharmacological treatments include the use of drugs that are also used in the treatment of Parkinson’s disease such as L-DOPA and pramipexole, and the use of magnesium sulphate therapy (as reported in a 2006 paper in the Journal of Clinical Sleep Medicine – magnesium is known to be a natural muscle relaxant). In a 2011 issue of the journal Sleep Medicine, In an online article about RLS, Dr Michael Platt, author of the 2014 book Adrenalin Dominance, claims that RLS sufferers can be treated using a progesterone cream:

“Excess adrenalin during the night can cause restless leg syndrome. People often have associated symptoms also resulting from elevated adrenalin, such as teeth grinding, the need to urinate, and tossing and turning, and they often awaken in the morning with low back pain. Characteristically, RLS patients have an excess of adrenaline, may toss and turn all night, be quick to anger, might be workaholics, will usually have fibromyalgia (aches and pains – low back, side of the hips, and grind their teeth), they might drink too much, and will be hypoglycemic (sleepy between 3-4 p.m. or when in a car), and so on. There is an associated over-production of insulin and an under-production of progesterone…[By using a progesterone cream] I have had 100% success with eliminating RLS by getting hormones into balance, often within the first week. Patients feel more relaxed, they can sleep at night, rage disappears, and they can focus more easily”.

Dr. Luis Marin and his colleagues reported a different treatment for RLS altogether. They reported the case of a 41-year-old male RLS sufferer who after being on medication for RLS discovered his own solution – having sex. Following sex, the man reported that all RLS symptoms would disappear. Marin and colleagues speculated that the release of dopamine following orgasm might alleviate RLS symptoms. This appears to be a reasonable speculation given the findings of research published in the Journal of Neuroscience by Dr. Gert Holstege and his colleagues who examined brain activation at the point of ejaculation. In their paper they reported the similarity between ejaculation and using heroin in terms of brain activation:

“We used positron emission tomography to measure increases in regional cerebral blood flow during ejaculation compared with sexual stimulation in heterosexual male volunteers. Manual penile stimulation was performed by the volunteer’s female partner. Primary activation was found in the mesodiencephalic transition zone, including the ventral tegmental area, which is involved in a wide variety of rewarding behaviors. Parallels are drawn between ejaculation and heroin rush”.

It could well be that the increase in dopamine following ejaculation acts in a similar way to the medications that are given to RLS sufferers. Of all the treatments for RLS that I have read about, I think I know which one I would prefer!

Dr. Mark Griffiths, Professor of Behavioural Addiction, International Gaming Research Unit, Nottingham Trent University, Nottingham, UK

Further reading

Allen, R.P., & Earley, C.J. (2001). Restless legs syndrome: A review of clinical and pathophysiologic features. Journal of Clinical Neurophysiology, 18(2), 128-147.

Bartell S1, Zallek S. Intravenous magnesium sulfate may relieve restless legs syndrome in pregnancy. Journal of Clinical Sleep Medicine, 15, 187-188.

Chaudhuri, K.R., Appiah-Kubi, L.S., & Trenkwalder, C. (2001). Restless legs syndrome. Journal of Neurology, Neurosurgery & Psychiatry, 71(2), 143-146.

Ekbom, K., & Ulfberg, J. (2009). Restless legs syndrome. Journal of Internal Medicine, 266(5), 419-431.

Holstege, G., Georgiadis, J. R., Paans, A. M., Meiners, L. C., van der Graaf, F. H., & Reinders, A. S. (2003). Brain activation during human male ejaculation. Journal of Neuroscience, 23(27), 9185-9193

Leschziner, G., & Gringras, P. (2012). Restless legs syndrome. British Medical Journal, 344, e3056.

Marin, L.F., Felicio, A.C., & Prado, G.F. (2011). Sexual intercourse and masturbation: Potential relief factors for restless legs syndrome? Sleep Medicine, 12(4), 422.

Ondo, W. G. (2009). Restless legs syndrome. Neurologic Clinics, 27(3), 779-799.

Ramar, K; Olson, EJ (Aug 15, 2013). Management of common sleep disorders. American Family Physician, 88, 231–238.

Satija, P., & Ondo, W. G. (2008). Restless legs syndrome. CNS Drugs, 22(6), 497-518.

Horticulture clash: Can gardening be addictive?

Back in November 2000, I appeared in numerous tabloid newspapers around the world in a story about ‘gardening addiction’ (such as one in the Daily Mail – ‘Professor says gardening is addictive’). It all began after I was interviewed by a journalist from the New Scientist magazine (Andy Coghlan). Coghlan wanted my reaction to a study published in the journal Biological Psychology led by my friend and colleague, Dr. Gerhard Meyer (with who I later co-edited the book Problem Gambling in Europe in 2009). Meyer and his colleagues had carried out a study on blackjack players and showed that they increased their heart rates while gambling (something that I also found in an earlier study I published on arousal in slot machine gamblers in a 1993 issue of the journal Addictive Behaviors). Meyer’s study also found that blackjack gamblers playing for money also had increased levels of salivary cortisol compared to blackjack gamblers playing for points.

I was asked by Coghlan whether I thought gambling could be a genuine addiction, even though it didn’t involve the ingestion of a psychoactive substance. I systematically went through my addiction components model (salience, mood modification, tolerance, withdrawal symptoms, conflict, and relapse) and spent about 15 minutes talking about my research on various behavioural addictions. When the New Scientist article was published, the only quote attributed to me was the following:

“Some people say you can’t have addiction unless you take a substance, but I would argue that gambling taken to excess is an addiction. If you accept that, you then accept that sex, computer games, even gardening, can be addictive. It opens up the floodgates to everything else”.

I had quite deliberately used the example of gardening to make the point that addiction should be assessed by standard addiction criteria and that if any behaviour fulfils all the criteria for addiction it should be classed as such irrespective of what the behaviour is. I also said in my interview with the New Scientist that I had never come across a case of gardening addiction but that it was theoretically possible. The New Scientist story was re-written by many different news outlets around the world. My comments were included in all of these stories. Some of these stories were reported with the focus being on the gambling study (such as the one reported by the BBC which you can read here). Others such as the Daily Mail and the New York Post (NYP) made my comments as the focus of the story. Here is what the NYP reported under the headline ‘Garden-variety junkies hooked on hobby’:

“Before you stop to smell the roses, you might want to think twice. People who enjoy gardening are as physically addicted as junkies and alcoholics, researchers claim. The findings by scientists at Bremen University in Germany are controversial because many experts refuse to believe that behavior can be addictive…The scientists also found the same is true of sex and gambling. They studied gamblers and measured the amounts of a stress hormone linked to addiction. Dr. Gerhard Meyer asked 10 gamblers in a casino to play blackjack, staking their own money. While the volunteers played, Meyer measured changes in their heart rates and levels of the stress hormone cortisol in their saliva. He then asked them to play for points rather than money, as a ‘control’ situation. Both heart rates and cortisol concentrations were markedly higher when the gamblers played for money…People who use addictive narcotics also have increased cortisol levels, which, in turn, can trigger the ‘addiction chemicals’ dopamine and seretonin in the brain. ‘Some people say you can’t have addiction unless you take a substance, but I would argue that gambling taken to excess is an addiction’, psychologist Mark Griffiths said. ‘If you accept that, you then accept that sex, computer games, even gardening, can be addictive. It opens up the floodgates to everything else’. If the new research is correct, gardening, gambling and sex, which involve pleasurable rewards for effort expended, could set up an addictive chemical pathway in the brain…Meyer says his findings might reduce the culpability of people who have committed crimes. If lawyers can attribute their clients’ crimes to physiological cravings rather than acts of free will, they may receive lighter sentences, he says”.

I spent much of the week in the media trying to get what I had actually said into context (and even appeared on Channel 4’s Big Breakfast television show defending what I had said). The Daily Mail article had sought comment from TV’s most high profile gardening expert Alan Titchmarsh who said: “[Gardening] is a very addictive pursuit. Once you’ve discovered the thrill of making things grow, you can’t stop. I get very twitchy if I can’t get outside and garden for a few days. It is an addiction – but a positive, useful addiction”. While I have no doubt Titchmarsh believed gardening to be a positive addiction (and would fulfil Dr. Bill Glasser’s criteria for positive addiction that I examined in a previous blog), it wouldn’t be an addiction using my own criteria. I wrote a letter to the New Scientist that they published on November 22 (2000) under the title ‘All kinds of addiction’. In that letter I wrote:

“My alleged comments about gardening addiction have been taken totally out of context and I would like to set the record straight, particularly as many of the national media appeared to have had a laugh at my expense following your press release on this story. My comments were made in reaction to the research by Meyer on gambling addiction, and whether I thought gambling was a true addiction because it didn’t involve a drug. I replied that any behaviour, be it gambling, sex, eating, Internet use, playing computer games or even, theoretically, gardening, that features all the core components of addiction, that is to say, mood-modifying effects, withdrawal symptoms, build-up of tolerance, total preoccupation with the activity, loss of control, neglect of everything else in their lives and relapse can be classed as an addiction. This was not reported in your article, leaving me wide open to misinterpretation. For the record, I have never said that gardening is addictive. What I have said is that any behaviour that fulfils the criteria for addiction can be operationally defined as addiction”.

On the same day (November 22), the Daily Mail also published an edited version of the letter I sent to the New Scientist buried away on page 73 (which you can read here) under the title ‘Eh, not quite’. In retrospect, I can smile about the whole incident, but I wasn’t smiling at the time. In a 2005 paper in the Journal of Substance Use, I subtly included a reference to the ‘gardening addiction’ story (or rather the lack of it) in a paper examining the nature of addiction:

It is also important to acknowledge that the meanings of ‘addiction’, as the word is understood in both daily and academic usage, are contextual, and socially constructed (Howitt, 1991; Irvine, 1995; Truan, 1993). We must ask whether the term ‘addiction’ actually identifies a distinct phenomenon – something beyond problematic behaviour – whether socially constructed or physiologically based. If so, what are the principal features of this phenomenon? If we argue that it is hypothetically possible to be addicted to anything, it is still necessary to account for the fact that many people become addicted to alcohol but very few to gardening. Implicit within our understanding of the term ‘addiction’ is some measure of the negative consequences that must be experienced in order to justify the use of this word in its academic or clinical context. It seems reasonable at this stage to suggest that a combination of the kinds of rewards (physiological and psychological) and environment (physical, social and cultural) associated with any particular behaviour will have a major effect on determining the likelihood of an excessive level of involvement in any particular activity”.

I have still to come across anyone that I would say is genuinely addicted to gardening. However, I did come across an interesting paper on unusual compulsive behaviours caused by individuals receiving medication for Parkinson’s disease. The paper was published in a 2007 issue of the journal Parkinsonism and Related Disorders by Dr. Andrew McKeon and his colleagues. They reported seven case studies of unusual compulsive behaviours after treating their patients with dopamine agonist therapy (i.e., treatment that activates dopamine receptors in the body). One of the cases involved a man who developed a gardening compulsion:

“A 53-year-old male with [Parkinson’s disease] for 13 years became intensely interested in lawn care. He would use a machine to blow leaves for 6 [hours] without rest, finding it difficult to disengage from the activity, as he found the repetitive behavior soothing. He also developed compulsive gambling”.

This case study at least suggests that someone can develop addictive and/or compulsive like behaviour towards gardening but is obviously isolated and very rare (and in this case brought on by the medication taken). I am not aware of any empirical research on gardening addiction since my comments on the topic back in 2000. However, I still stick to my assertion that if the rewards are present (i.e., psychological, social, physiological, and/or financial), it is theoretically possible for people to become addicted to almost anything – even gardening.

Dr. Mark Griffiths, Professor of Gambling Studies, International Gaming Research Unit, Nottingham Trent University, Nottingham, UK

Further reading

Glasser, W. (1976). Positive Addictions. New York, NY: Harper & Row.

Griffiths, M.D. (1996). Behavioural addictions: An issue for everybody? Journal of Workplace Learning, 8(3), 19-25.

Griffiths, M.D. (1993). Tolerance in gambling: An objective measure using the psychophysiological analysis of male fruit machine gamblers. Addictive Behaviors, 18, 365-372.

Griffiths, M.D. (2000). All kinds of addiction New Scientist, November 22, p 58.

Griffiths, M.D. (2005). A ‘components’ model of addiction within a biopsychosocial framework. Journal of Substance Use, 10, 191-197.

Hoffmann, B. (2000). Garden-variety junkies ‘hooked’ on hobby: Study. New York Post, November 10. Located at: http://nypost.com/2000/11/10/garden-variety-junkies-hooked-on-hobby-study/

Howitt, D. (1991). Concerning Psychology. Milton Keynes: Open University Press.

Irvine, J. M. (1995). Reinventing perversion: Sex addiction and cultural anxieties. Journal of the History of Sexuality, 5, 429–450.

Meyer, G., Hauffa, B. P., Schedlowski, M., Pawlak, C., Stadler, M. A., & Exton, M. S. (2000). Casino gambling increases heart rate and salivary cortisol in regular gamblers. Biological Psychiatry, 48(9), 948-953.

Meyer, G., Hayer, T. & Griffiths, M.D. (2009). Problem Gaming in Europe: Challenges, Prevention, and Interventions. New York: Springer.

McKeon, A., Josephs, K. A., Klos, K. J., Hecksel, K., Bower, J. H., Michael Bostwick, J., & Eric Ahlskog, J. (2007). Unusual compulsive behaviors primarily related to dopamine agonist therapy in Parkinson’s disease and multiple system atrophy. Parkinsonism & Related Disorders, 13(8), 516-519.

Truan, F. (1993). Addiction as a social construction: A postempirical view. Journal of Psychology, 127, 489-499.

Strange fascinations: A brief look at unusual compulsive and addictive behaviours

In previous blogs, I have examined lots of strange types of addictive and compulsive behaviours including compulsive singing, compulsive hoarding, carrot eating addiction, Argentine tango addiction, compulsive nose-picking, compulsive punning, compulsive helping, obsessive teeth whitening, compulsive list-making, chewing gum addiction, hair dryer addictionwealth addiction, and Google Glass addiction (to name just a few).

However, while doing some research for a paper I am writing on ‘fishing addiction’ (yes, honestly), I came across an interesting paper on unusual compulsive behaviours caused by individuals receiving medication for Parkinson’s disease ([PD] a degenerative disorder of the central nervous system) and multiple system atrophy ([MSA] a degenerative neurological disorder in which nerve cells inside the brain start to degenerate and with symptoms similar to Parkinson’s disease).

In the gambling studies field there are now numerous papers that have been published showing that some Parkinson’s patients develop compulsive gambling after being treated for PD. According to the Parkinsons.co.uk website, those undergoing PD treatment can have many side effects including addictive gambling, obsessive shopping, binge eating, and hypersexuality. The website also notes other types of compulsive behaviour that have been associated with PD medication including “punding or compulsive hobbyism [when someone does things such as collecting, sorting or continually handling objects]. It may also be experienced as (i) a deep fascination with taking technical equipment apart without always knowing how to put it back together again, (ii) hoarding things, (iii) pointless driving or walking, and (iv) talking in long monologues without any real content”.

The paper that caught my eye was published in a 2007 issue of the journal Parkinsonism and Related Disorders by Dr. Andrew McKeon and his colleagues. They reported seven case studies of unusual compulsive behaviours after treating their patients with dopamine agonist therapy (i.e., treatment that activates dopamine receptors in the body). The paper described some compulsive behaviours that most people would not necessarily associate with being problematic. Below is a brief description of the seven cases that I have taken verbatim from the paper.

  • Patient 1: “A 65-year-old female with PD for 9 years developed compulsive eating, and also felt compelled to repetitively weigh herself at frequent intervals during the day and at night. She found her behavior both purposeless and repetitive. Obsessive thoughts were also a feature, as the patient ‘had to’ weigh herself three times each occasion she used the weighing scales”.
  • Patient 2: “A 67-year-old female with PD for 8 years played computer games and solitaire card games for hours on end, often continuing to do so through the night. She did not enjoy the experience and found it purposeless, but did so as she felt she had ‘to be doing something’. She also developed compulsive eating and gambling”.
  • Patient 3: “A 48-year-old male with PD for 5 years, with little prior interest, developed an intense interest and fascination with fishing. His wife was concerned that he fished incessantly for days on end, and his interest did not abate despite never catching anything. This patient also developed compulsive shopping, spending large amounts of time and money in thrift stores”.
  • Patient 4: “A 53-year-old male with PD for 13 years became intensely interested in lawn care. He would use a machine to blow leaves for 6h without rest, finding it difficult to disengage from the activity, as he found the repetitive behavior soothing. He also developed compulsive gambling”.
  • Patient 5: “The wife of a 52-year-old male with an 11-year history of PD complained that her husband now spent all of his time on his hobbies, to the detriment of their marriage. The patient made small stained glass windows, day and night. In addition, he would frequently stay awake arranging rocks into piles in their yard, intending to build a wall, but never doing so. He would start multiple projects but complete nothing. He was also noted to have become hypersexual, demanding sexual intercourse from his wife several times daily”.
  • Patient 6: “This 60-year-old male, with a history of alcohol abuse and ultimately diagnosed with MSA, relentlessly watched the clock, locked and unlocked doors and continually arranged and lined up small objects on his desk. He also became hyperphagic and hypersexual, developing an intense fascination with pornographic films”.
  • Patient 7: “The wife of a 59-year-old male with PD for 1 year described how her husband dressed and undressed several times daily. On one occasion, while guests were at their house for dinner, he spent most of his time in his bedroom repeatedly changing from one pair of trousers into another. This behavior deteriorated considerably on increasing levodopa dose to 1100mg/day, and on a subsequent occasion after reducing quetiapine from 100 to 75 mg/day”.

These cases highlight that the compulsive behaviours that develop following dopamine agonist therapy often co-occur with one or more other compulsive behaviour and that much of these behaviours are repetitive and unwanted. As the authors noted:

“The temporal association between medication initiation and the onset of these behaviors led to our suspicion that medications were causative. In the aggregate, these patients illustrate that the behaviors provoked by drug therapy in parkinsonism cover a broad spectrum, ranging from purposeless and repetitive to complex, reward-oriented behaviors. Punding is the term typically applied to the former, and was seen in Patient 5 (arranging rocks into piles) and Patient 6 (lining up small objects on a desk)…Previous descriptions of pathological behaviors occur- ring with dopaminergic therapy in PD have been notable for the absence of obsessive thoughts accompanying compulsive behaviors, unlike Patient 1 who was remark- able for a counting ritual accompanying repetitive use of a weighing scale. In six of the seven cases, other reward- seeking behaviors (gambling, shopping, hypersexuality or overeating) were present and contemporaneous with these other unusual compulsive behaviors. This suggests that all of these behaviors, while phenomenologically distinct, are all part of the range of psychopathology encapsulated by obsessive-compulsive spectrum disorders”.

According to the Parkinsons.co.uk website, PD sufferers are more likely to experience impulsive and compulsive behaviour if the person is (i) diagnosed with Parkinson’s at a young age, (ii) male, (iii) single and live alone, (iv) a smoker, and (v) someone with a personal or family history of addictive behaviour. The same article also notes that if the PD sufferer has a history of ‘risk-taking’, such as gambling, drug abuse or alcoholism, [they] may be more likely to develop dopamine addiction”. This is where the PD sufferer takes more of their medication than is needed to control their Parkinson’s symptoms (and known as dopamine dysregulation syndrome). Similarly, Dr. McKeon and colleagues concluded:

“Previously described associated clinical features include a prior history of depressed mood (four patients in this series), disinhibition, irritability and appetite disturbance…A history of problems with impulse control prior to the diagnosis of PD may be a risk factor for developing compulsive behaviors with dopaminergic therapies…although this only pertained to Patient 6…The compulsions were not found to be troublesome by three patients, with complaints regarding behavioral change coming from the patient’s spouse. Our observations affirm the need to check with both patient and family at follow-up visits for the emergence of a variety of troublesome pathological behaviors that may result from dopaminergic therapy, particularly dopamine agonists”.

Dr. Mark Griffiths, Professor of Gambling Studies, International Gaming Research Unit, Nottingham Trent University, Nottingham, UK

Further reading

Dodd, M. L., Klos, K. J., Bower, J. H., Geda, Y. E., Josephs, K. A., & Ahlskog, J. E. (2005). Pathological gambling caused by drugs used to treat Parkinson disease. Archives of Neurology, 62, 1377-1381.

Griffiths, M.D. (1996). Behavioural addictions: An issue for everybody? Journal of Workplace Learning, 8(3), 19-25.

Griffiths, M.D. (2005). A ‘components’ model of addiction within a biopsychosocial framework. Journal of Substance Use, 10, 191-197.

Klos, K. J., Bower, J. H., Josephs, K. A., Matsumoto, J. Y., & Ahlskog, J. E. (2005). Pathological hypersexuality predominantly linked to adjuvant dopamine agonist therapy in Parkinson’s disease and multiple system atrophy. Parkinsonism and Related Disorders, 11, 381-386.

McKeon, A., Josephs, K. A., Klos, K. J., Hecksel, K., Bower, J. H., Michael Bostwick, J., & Eric Ahlskog, J. (2007). Unusual compulsive behaviors primarily related to dopamine agonist therapy in Parkinson’s disease and multiple system atrophy. Parkinsonism and Related Disorders, 13(8), 516-519.

Nirenberg, M. J., & Waters, C. (2006). Compulsive eating and weight gain related to dopamine agonist use. Movement Disorders, 21, 524-529.

Pontone, G., Williams, J. R., Bassett, S. S., & Marsh, L. (2006). Clinical features associated with impulse control disorders in Parkinson disease. Neurology, 67, 1258-1261.

Voon, V., Hassan, K., Zurowski, M., De Souza, M., Thomsen, T., Fox, S.,…& Miyasaki, J. (2006). Prevalence of repetitive and reward-seeking behaviors in Parkinson disease. Neurology, 67, 1254-1257.