Impulse Control Disorder secondary to Dopaminergic therapies in Parkinson’s – Evaluating Risk

Summary

Impulse control disorder (ICDs) can result in serious consequences for patients, their carers and families. They are characterized by a failure to resist a temptation, urge or impulse that may cause harm to oneself or others. They occur secondary to dopaminergic therapies in Parkinson’s, especially Dopamine agonists (DA). There is a dose and duration of treatment association. They may be accompanied by a degree of compulsion to act which increases risk. Risk factors associated their development have been identified including younger age at onset, being male, living alone, genetic and family history and preceding history of impulse control traits. A variety of screening tools exist but do not replace the detailed clinical interview. They may lead to criminal acts and consequent judicial proceedings, and whilst sentences may be commuted due to impaired capacity, the impact is frequently devastating. Class action law suits have been sought against the drug companies and prescribers have a clear medico-ethical responsibility for monitoring the drugs they prescribe. Management is often difficult and limited, necessitating slow withdrawal of the agent, and risk needs to be evaluated and managed throughout this period. An outline structure for evaluating risk is delineated focusing on areas of pre-disposing factors; detailed history of ICDs; degree of control and elucidation of risks.

Relationship between dopaminergic therapies in Parkinson’s and ICD

Impulse control disorders are characterized by a failure to resist a temptation, urge or impulse that may cause harm to oneself or others¹. Patients pursue certain ‘reward-based’ activities with lack of considered decision evaluation and without thought to the personal and interpersonal consequences that might arise. In psychiatric terms, to be a disorder, these impulse driven behaviours must affect one area of functioning, this includes not just activities of daily living but also inter-personal and social functioning.

The nature of these disorders is varied and includes pathological gambling, hypersexuality, uncontrolled shopping, eating, internet use and various arts and crafts activities. The risks associated with impulse control disorders is activity dependent but at the least, they can cause significant functional impairment and strained interpersonal relationships, and at worst, can result in criminal prosecution with lasting harm to self and others².

Studies to date have suggested that ICDs are more common in treated PD patients than in the general population or healthy controls³⁴, one study suggested otherwise⁵. It is important to note that there are no accepted diagnostic criteria for certain ICDs including hypersexuality which may contribute to variance seen in studies².

In a recent prospective study of DA-treated patients, 39% without an ICD at baseline prior to treatment initiation developed one within 4 years, with a median duration of onset of 23 months⁶.

In the DOMINION study, DA treatment was associated with a 2 to 3.5 fold increased odds of having an ICD. ICD prevalence was 17.1% in patients treated with a DA and 6.9% in patients not taking a DA⁷. There does not seem to be any appreciable difference in prevalence between the second generation nonergot Das, however shorter acting Das and Rotigotine were subsequently found to have higher incidence

The DA selectivity for D2-like receptors (D2 and D3 receptors) which are colocalized in the mesocorticolimbic pathway is important in appreciating the mechanism of increased risk for development of ICDs.²

Use of levodopa, especially at higher doses⁷ and Amantadine⁸ have also been associated with the development of ICDs although of lower prevalence than with DA. An association with MAOI-B inhibitor use has also been reported⁹where they were used alongside DA.

DBS was originally thought to decrease the incidence and this appears to correlate with decreased DA use following DBS interventions.¹⁰ Recent studies suggest an increase in impulsive decision making when DBS stimulators are turned on and premature responding¹¹. However, there is evidence of improved inhibitory control later in the reaction process implying the STN plays a role in dynamic aspects of impulse and inhibitory control in goal direction¹².

Dopaminergic function, notably in the mesocorticolimbic system, plays a critical role in the mediation of reward and reinforcement behaviours. Brain regions most commonly implicated in ICDs include: 1) the caudal orbitofrontal cortex and possible ventromedial prefrontal cortex (PFC) which are involved in planning and judgement; 2) the ventral striatum (VS; particularly the nucleus accumbens [NAc], crucial for the reward system; 3) the amygdala, involved in conditioned responses and emotional processing and 4) medial dorsal and anterior nucleus of the thalamus¹³,².

Alterations in this circuitry contribute to the development of ICDs, projections in the ventral components of the striatum (including the NAc) more implicated in urges and impulsivity and those engaging the dorsal striatum more implicated in motor habits and compulsivity. Mesolimbic and mesocortical pathways are responsible for reward learning and executive decision making, respectively, with dysregulation of the mesolimbic system underlying the clinical manifestation of impulsive and compulsive behaviours.¹⁴,¹⁵,¹⁶

Dorsal striatal changes appear to account for the translation from impulsive to compulsive addiction. ¹⁷

Impulse control and compulsion to act

Impulse control disorders are traditionally recognised as reward driven behaviours, seeking pleasurable activities without consideration of consequences to self or others. They are regarded as essentially egosyntonic, which is to say, representing the desires of the individual, the behaviours, feelings and thoughts are congruent with the ‘self’.

Compulsive disorders are traditionally characterised as egodystonic, that is to say at variance with self. They are not recognised as being concordant with the person’s ‘self’ but rather acts which are undertaken to relieve anxiety, tension or distress and are not characterised by a sense of reward, but rather relief.

Whilst historically regarded as being polar opposites, there is increasing recognition of these disorders as part of a continuum or spectrum.¹⁸, ¹⁹, ²⁰ The studies from psychiatric impulse control disorders such as pathological gambling and addiction, have found that whilst there may be initial ‘reward’ driven behaviour this often becomes, over time, compulsive. Behaviours are driven despite a desire not to continue and a diminishing experience of reward. The behaviours are difficult to resist and associated more with release of tension (relief) rather than true ‘reward’.²¹

Likewise, in compulsive behaviours, these behaviours may themselves be associated with intrinsic pleasure over time rather than simply relief of distress/tension.

Within the literature around ICDs in PD there is frequent use of both terminologies. This does seem to be more than just a simple ‘fudging’ of semantics. The compulsive disorders such as punding and dopamine dysregulation syndrome are often grouped as related disorders. Compulsivity is often referred to in describing the nature of the ICDs seen in PD. There appears to be recognition amongst clinicians of compulsion to act as well as a lack of inhibition to act in ICDs in this context.²²

To what extent this can be measured across a group of patients appears to vary according to rating scales used with some showing increased sensitivity for establishing the presence of compulsive elements within patients who have ICDs. (see below)

It may be the English dictionary definition which lends itself to an appreciation of the use of the word compulsion in describing ICDs, “an irresistible urge to behave in a certain way” “the action or state of forcing or being forced to do something”. The irresistibility of the urge and the feeling of being driven to act are recognisable components for many with ICDs.²³

A thought or feeling can be at the same time both egosyntonic and egodystonic. This dissonance or ambivalence is a normal part of ourselves. Societal rules and conditioning, fear of consequences and evaluative planning functions will usually cause us to pursue one course of action over another. However, where there is a fundamental dysfunction in the neurobiological regulatory mechanisms as elucidated above, then action can result which is both harmful to self as to others as regulation breaks down.

The extent to which a person may be able to moderate their ICD behaviour can be influenced by both the degree of dysfunction in brain circuitry but also in the combination of difficulty in controlling impulses and drivers which are more compulsive in nature.²⁴,²⁵

Understanding and accepting this interplay may be essential in analysing and managing risks.

It is unclear how far the dysexecutive impairments in PD may influence both planning in ICD and control or inhibition of responses. Studies show that PD patients have reduced response dis-inhibition and delayed response inhibition.

Executive dysfunction can be present from the early stages of Parkinson’s disease (PD). It is characterized by deficits in internal control of attention, set shifting, planning, inhibitory control, dual task performance, and on a range of decision-making and social cognition tasks ²⁶, ²⁷

Risk Factors

Two studies have compared the occurrence of ICDs in patients newly diagnosed with PD (pre-medication) and healthy controls and found no significant difference in rates between the two groups. The primary findings are that PD itself does not confer an increased risk of developing ICDs²⁸, ²⁹.

The causal link has been established as the use of dopamine replacement therapy, most specifically dopamine agonists and is supported by the emergence of ICDs in other patient groups exposed to DA treatment (restless leg syndrome, fibromyalgia and pituitary adenomas, and case reports with aripiprazole a partial dopamine agonist). ²

No difference has been found between the dopamine agonists as a class in incidence, however longer acting and transdermal formulations seem to have reduced incidence³⁰ and there is a dose-effect relationship; both increasing duration and dose are associated with ICDs. ³¹

Levodopa use at high dose is also associated with the development of ICDs.

The odds of having an individual ICD were 2 to 3.3 times higher in patients treated with DA than those not treated with them.

Clinical correlates of risk for the development of ICDs in response to DRT from various studies and case reports ⁷, ¹⁴, ²,³², ³³, include;-

• Younger age at onset of PD
• Longer duration of PD
• History of ICD symptomatology prior to PD
• Premorbid personal history of alcohol misuse disorder
• Family history of alcohol misuse disorder
• Family history of bipolar affective disorder
• Family history of gambling problems
• Current cigarette smoking
• Male gender
• Being unmarried

There are emerging lines of work pointing to unique pathological changes that impact value based decision making in PD patients. PD patients commonly display a range of impairment in executive abilities including action control, response inhibition and delayed discounting³⁴. These deficits localise to impaired frontal-striatal tracts likely secondary to neurochemical dysfunction within the SN and striatum³⁵.

In a study comparing PD patients with and without ICDs and non-PD populations with compulsive gambling, illicit drug use or no disorder, PD patients in general made more impulsive and irrational choices in a test of reflection impulsivity ³⁶, yet conventional interpretations of impulsivity show ICD patients have proficient motor control. This suggests that the cognitive and pathophysiological changes in ICD patients occur in reward based decisions making not motor control and medication induced changes to these networks underpin the cognitive changes associated with ICD³⁵.

De novo PD patients demonstrate intact punishment learning and impaired reward learning compared with healthy controls, whereas acute DA treatment reverses this pattern, leading to improved reward learning and decreased punishment learning ³⁷

In a study using intertemporal choice task (delayed discounting) PD patients without an ICD showed an increase in impulsive decision making, regardless of medication status, compared with healthy controls ³⁸

Recent studies using genotypes from 13 candidate variants significantly increased ICD predictability compared to clinical variables alone (AUC = 76% vs AUC 65%). The clinical genetic prediction model reached highest accuracy in patients initiating DA therapy (AUC = 87% 95%CI [80 – 93%]). Opioid (OPRK1), serotonin (HTR2A), and dopamine (DDC) genotypes were the strongest genetic predictive factors. These results suggest potential for development of genetic screening tests in guiding dopaminergic therapy for the future.³⁹

Screening tools

A recently commissioned review of clinical screening instruments and rating scales by the International Parkinson’s and movement disorder society assessed numerous available rating scales including their clinimetric properties for impulse control disorders and compulsive behaviours (together called ICBs).⁴⁰

A scale was designated ‘recommended’ if it had been used in PD studies, been used beyond the group that developed it and had adequate clinimetric data published for PD. The clinimetric properties were assessed against a ‘gold standard’ semi-structured interview.

Numerous diagnostic screening tools and rating scales were identified for a range of ICBs including compulsive medication use (CMU), punding/hobbyism, walkabout, pathological gambling, hypersexuality, compulsive or binge-eating disorder (CE), compulsive buying (CB), reckless driving, compulsive exercise, pyromania, trichotillomania, hoarding, kleptomania, intermittent explosive disorder and internet addiction.

For screening across the range of ICBs (except compulsive medication use), the Questionnaire for Impulsive-compulsive disorders in Parkinson’s disease (QUIP) and QUIP-rating scale (QUIP-RS) are recommended, and for severity rating across the range of ICBs the QUIP-RS and the Ardouin Scale of behaviour in PD are recommended. The Scale for Outcomes in Parkinson’s disease-psychiatric complications is recommended for rating of hypersexuality and the compulsive behaviours gambling/shopping.

The QUIP is divided into 3 sections: 1) 5 questions (including an introductory question describing the problem behaviours) for the 4 most common ICDs reported in PD, 2) 3 distinct introductory questions and 2 additional questions for hobbyism, punding and walkabout; and 3) 5 questions including a short introductory question for CMU

The QUIP-RS is a brief 28-item patient-reported or clinician-rated scale derived from QUIP for measure of severity of ICDs. Each item is rated on a 5-point Likert scale assessing frequency of symptoms with a range of scores form 0 (never) to 4 (very often). The questions relate to the 4 most common ICDs (PG, CE, CB, and HS), hobbyism and punding combined as a single diagnosis and CMU during the last 4 weeks.

The Ardouin Scale of behaviour in PD (ASBPD) is a semi-structured interview that assesses neuropsychiatric modifications routinely encountered in PD. The scale is rated by a psychiatrist or psychologist familiar with PD and raters must be trained. The timeframe assessed is a month preceding the interview.

Items are rated on a 5 point scale from 0 (absence) to 4 (severe)accounting for the severity and frequency of the disorder and its psychosocial effect. Individual items are grouped into 3 subscales. The hypodopaminergic behaviour (depressed mood, anxiety, irritability and aggressiveness, hyperemotionality and apathy. The subscale evaluates non motor on (euphoria) and off (dysphoria) fluctuations. The hyperdopaminergic behaviours subscale measures the presence and severity of behavioural disorders typically induced by dopaminergic medication. These include hypomanic mood, psychotic signs, nocturnal hyperactivity, diurnal somnolence, increased eating behaviour, creativity, hobbyism, punding, risk-taking behaviour, compulsive shopping, pathological gambling, hypersexuality, dopaminergic addiction, and overall excess motivation.

The Scale for Outcomes in Parkinson’s Disease –psychiatric complications (SCOPA-PC) is a screening and severity scale that consists of a 7 item clinician-rated, semi-structured questionnaire administered to the patient and caregiver for the preceding month. It assesses a broad range of psychiatric symptoms, including 2 items that relate to compulsive behaviours (1 item for hypersexuality and 1 combined item for compulsive shopping and pathological gambling). The scores range from 0 (no symptoms) to 3 (severe symptoms).

Categorical rating tools can help clinicians screen for ICBs, identify ICBs early in their course, aid treatment and management decisions and monitor pharmacological management. It is desirable to screen for multiple ICBs in a patient displaying one abnormal behaviour as the presence of multiple ICBs in a given individual is associated with more severe depression, poorer quality of life and treatment resistance.

The QUIP and QUIP-RS include questions specific to the ‘urge’ of performing a particular behaviour, mediated by the ventral striatal systems, this does not necessarily involve the execution of that behaviour (i.e. with increased involvement of dorsal striatal systems). Nearly 40% of patients without an ICD diagnosis scored positively on the QUIP implying a sub-syndromal symptoms experience not translated into action.

An on-going issue is the discrepancy between patient and informant reporting of symptoms which is high⁴¹. The most likely explanation being a complex relationship between insight and ‘addiction’ behaviours, as well as embarrassment. Interestingly a recent study⁴² found that ICD severity in PD patients was correlated with alexithymia, specifically difficulty describing feelings as opposed to externally orientated thinking and may contribute to under-reporting.

The screening tools whilst helpful do not replace a comprehensive clinical interview in identifying and appraising harmful behaviours.

Criminality and the law in ICD

The issue of whether ICDs arising from dopaminergic treatment and resulting in criminal acts fulfil the M’Naghten’s ‘rules’ is a contentious one⁴³.

M’Naghten’s case (1843), 10 Cl. & Fin. 200, 8 E.R. 718 (H.L.) To “establish a defence on the ground of insanity,” Chief Justice Tindal wrote “it must be clearly proved that at the time of the committing of the act, the party accused was labouring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act he was doing; or, if he did know it, that he did not know he was doing what was wrong”

The question of whether this should morally or instrumentally be extended to other situations where the defendant understands the wrongfulness of their actions but are incapable of resisting an impulse to commit them

This has been known as the “irresistible impulse” defence or as the “control” or “volitional” test for insanity, recognised in some jurisdictions but not others.

Defendants are rarely assessed as being “Not criminally Responsible” on the basis of volitional incapacity alone, and there is no evidence of this being utilised as a broad brush accepted defence with general impulse control disorders like kleptomania.

Many courts have stressed that ‘irresistible impulse’ cannot apply when there is evidence of planning or deliberation⁴³. These speaks to our assessment in medical terms of ‘capacity’ and the issue of whether at that moment in time, the person was able to weigh their decision in the balance.

In terms of the neuropsychological profile, it may also be considered whether that weighing in the balance was tipped by over-valuation of reward versus consequence decision making. The degree of compulsion to act must also be accounted for if present.

In many jurisdictions, evidence of impulse control disorder is proffered to support claims of diminished responsibility or in mitigation of punishment. The suggestion is a total exemption from responsibility should require a total incapacity to control conduct in the circumstances and that this is a difficult threshold to prove⁴³.

A 2018 study on “Capacity, control and responsibility in Parkinson’s disease patients with impulse control disorders: views of neurological and psychiatric experts”⁴⁴ explored the views of 11 neurologists, psychiatrists and geriatricians. Their findings revealed a degree of divergence in opinion of the issues. However, their conclusions were that they a) attributed ICDs to a variety of causes (see above risk factors for developing ICDs); b) considered ICD patients’ decision –making capacities and behavioural control to be partially but not totally compromised; c) were divided or ambivalent about ICD patients’ responsibility; and d) noted the difficulties inherent in assessing complex constructs such as “control” and “responsibility”.

In a number of commonwealth cases, it appears offending ICD patients have been considered to be suffering from “irresistible impulses” such that their decision making capacity and behavioural control and responsibility were totally compromised. This contrasts with the courts general scepticism in relation to drug induced compulsion in cases of addiction related offences and seems minded by the fact that in substance misuse, the defendant has a choice, whereas in PD the patient requires medication for treatment of their underlying condition and choice is restricted.

Whilst there is a debate on the ‘morality’ of the law and scientific basis for an offence the most useful guidance was provided by Vincent, N.A. (2011b) Legal responsibility adjudication and the normative authority of the mind sciences. Philosophical Explorations, 14, 315-331

“Although science lacks normative authority in this domain, its findings can have normative significance. This does not mean that courts should replace judges and juries with scientists, that science and scientists can henceforth dictate what norms we ought to endorse, to enforce and to reject, or that the moralising language of the law should be replaced with the morally neutral and maybe even medical lingo of psychology and neuroscience. But it does mean that scientific findings which shed light on the human condition should be taken seriously, and that received wisdom about normative issues should remain open to scrutiny, to reassessment, to criticism and even to reform in the light of relevant and accurate empirical findings”

There have been some notable cases in relations to debt encountered as part of pathological gambling. However perhaps most controversial is the issue of hypersexuality resulting in criminal acts. It can be argued that whilst impulse control disorders impair ability to control impulses, to weigh the decision to act in the moment against the many consequences and ramifications, they do not create those impulses.⁴⁵ The issue of paedophilic acts in this context is perhaps most disturbing for clinicians, society and the law. There is however a principle that a ‘thought’ is not a criminal offence, action is. In psychoanalytic views, we all have capacity for darker thoughts stemming from our “id” and the development of our superego or conscience is responsible for ensuring we do not act on these thoughts. The threat of punishment and consequence form part of our societal normalisation for accepted behaviours and rejection of unacceptable ones. A thought can be both egosyntonic and egodystonic at the same time, both exciting and repelling. If the dopamine driven reward system is in drive mode, it results in a disturbance of this balance, such that a person who has never acted on their ‘dark’ thoughts fails to resist the impulse to do so. This must be clearly differentiated from the above point of evidence of planning or deliberation which would negate this argument.

Medico-ethical considerations

GMC guidance on prescribing responsibility⁴⁶

“You should reach agreement with the patient on the treatment proposed, explaining:

a the likely benefits, risks and burdens, including serious and common side effects

b what to do in the event of a side effect or recurrence of the condition

e arrangements for monitoring, follow-up and review, including further consultation, blood tests or other investigations, processes for adjusting the type or dose of medicine, and for issuing repeat prescriptions.

Whether you prescribe with repeats or on a one-off basis, you must make sure that suitable arrangements are in place for monitoring, follow-up and review, taking account of the patients’ needs and any risks arising from the medicines

Reviewing medicines will be particularly important where:

a patients may be at risk, for example, patients who are frail or have multiple illnesses.

b medicines have potentially serious or common side effects……….”

NICE guidance⁴⁷

1.3.8 When starting treatment for people with Parkinson’s disease, give people and their family members and carers (as appropriate) oral and written information about the following risks, and record that the discussion has taken place:

• Impulse control disorders with all dopaminergic therapy (and the increased risk with dopamine agonists).

1.4 Managing and monitoring impulse control disorders as an adverse effect of dopaminergic therapy

Predictors for the development of impulse control disorders

1.4.1 Recognise that impulse control disorders can develop in a person with Parkinson’s disease who is on any dopaminergic therapy at any stage in the disease course. [2017]

1.4.2 Recognise that the following are associated with an increased risk of developing impulse control disorders:

• Dopamine agonist therapy.
• A history of previous impulsive behaviours.
• A history of alcohol consumption and/or smoking. [2017]

Information and support

1.4.3 When starting dopamine agonist therapy, give people and their family members and carers (as appropriate) oral and written information about the following, and record that the discussion has taken place:

• The increased risk of developing impulse control disorders when taking dopamine agonist therapy, and that these may be concealed by the person affected.
• The different types of impulse control disorders (for example, compulsive gambling, hypersexuality, binge eating and obsessive shopping).
• Who to contact if impulse control disorders develop.
• The possibility that if problematic impulse control disorders develop, dopamine agonist therapy will be reviewed and may be reduced or stopped. [2017]

1.4.4 Discuss potential impulse control disorders at review appointments, particularly when modifying therapy, and record that the discussion has taken place. [2017]

1.4.5 Be aware that impulse control disorders can also develop while taking dopaminergic therapies other than dopamine agonists. [2017]

There have been a considerable number of lawsuits, including class action suits, filed against the manufacturing drug companies of Dopamine Agonists in relation to ICDs resulting in serious financial and personal consequences. These have been significantly successful, particularly prior to the warning labels which are now issued with these medications.

An advocacy group is currently suing the FDA of failure to issue black box warnings to this class of medications.

The Parkinson’s UK forum²³ is replete with personal examples of the catastrophic consequences of ICDs and indeed the strength of feeling that people are not sufficiently warned or informed, that when they experience these symptoms they lack insight and may not make the link with medication. Sadly, if their carers, friends and family are not informed they are also unable to support them in understanding their behaviours and attributing to the treatment. Interestingly they also discuss the feeling in the early stages of symptoms of pleasure and the reluctance to acknowledge that there is a problem as they feel they are self-motivated and ‘enjoying’ their ‘ICD’. Financial loss and family collapse are commonly described, as well as judicial sentences and bankruptcy

The sense that not enough is done by prescribers and professionals to educate and inform, as well as monitor and support, comes across strongly.

There is then a clear ethical, professional and moral imperative for prescribers of dopaminergic treatments and dopamine agonists especially, to not only clearly inform patients about the risk of developing an ICD and educate them about the nature of these disorders, but to risk assess prior to treatment initiation based on known risk factors and to provide monitoring which is both frequent enough and in depth enough to detect ICDs before they become injurious.

Services available for PD patients are varied. Not all areas are able to draw on a comprehensive service and opportunities for follow up and monitoring may be limited. Not all health professionals involved in a patients’ care are sufficiently aware or skilled in detecting ICDs.

Evaluating Risks

Monitoring of dopaminergic medications (most especially DA) for ICDs medico-legally and ethically involves the prescriber having the structure to do so (or access to a structure which can do so).

The starting point for managing risks is a comprehensive risk analysis. The outline suggested below includes an analysis of pre-disposing factors and ideally this will have been done prior to starting dopamine agonist medication in particular and should predisposing factors be identified then dopamine agonists should be avoided if possible, if not, a robust mechanism for identifying ICDs early should be in place.

The nature of the ICD would be clearly elaborated and detailed (a separate analysis for each ICD where there is more than one). In the case of hypersexuality in particular, exploring the thoughts (fantasies, thoughts which excite but may be rejected etc..) will be essential to identify possible risks. Detail is the key here and it may be an uncomfortable area of discussion for both patient and practitioner.

Exploring means is also crucial in this section, where might there be opportunities, what access to the ‘desired’ object might the person have, what risks might they take in seeking access (debt, risky sexual liaisons etc.). Impulses may be associated with certain triggers eg. Passing a lotto sign, seeing a fire, and any triggers need to be carefully explored in terms of a discussion on how risk is subsequently managed. The degree to which the impulse is pursued will inform a rating of the severity of the risk posed.

As elaborated above, the degree of control may be variable. The impulse itself may feel ‘irresistible’, but if accompanied by a degree of compulsion to act then it is even more likely to occur. It may go on to become compulsive in nature as seen with addictions outside of this patient group.

If the reward is high, then reward learning takes place making repetition of the acts more likely. If the reward sensation is more muted by later awareness of consequences, then it is likely to be more amenable to behavioural management.

This analysis then leads on to elaboration of the actual risks, who may be harmed, in what way and under what circumstances. All the risks elaborated may have potentially devastating consequences personally for the patient and his/her family.

The table is not intended as a tick box exercise but rather a structure for thinking about risk with MDT members, patients and families.

Risk Analysis – Complete – Individual and collateral histories

Management

Whilst the primary management is reduction in dose and potential cessation of dopaminergic treatment, this is not always possible. Some patients may be unable to stop due to worsening motor symptoms and some patients are unable to reduce or discontinue due to Dopamine Agonist Withdrawal syndrome (DAWS – prevalence 15.5% to 19%)⁴⁸. This is a severe, stereotyped drug withdrawal syndrome specific to DA, and cannot be alleviated by levodopa or other PD medications. Symptoms include anxiety, panic attacks, dysphoria, fatigue, dysautonomia, sleep disturbance, generalised pain and medication cravings. These may be protracted and prevent reduction or cessation of DA treatment and the development of chronic ICDs (15%)².

Advice is to taper the withdrawal very slowly to try and avoid the development of DAWS over several months. This necessarily implies the management of the risks associated with the ICDs over that period⁴⁹.

There are limited pharmacological options with case reports demonstrating conflicting evidence and limited efficacy in many cases.

Atypical antipsychotics general worsen motor function and the choice is limited to quetiapine or clozapine which have been used to treat punding, PG and HS. Quetiapine is usually used first line due to the challenges of haematological monitoring with clozapine, however motor worsening can happen in 32% of patients⁴⁹, ⁵⁰. There are 2 case reports of Quetiapine triggering punding.

Amantadine has been used to treat punding and PG with some reported success⁵¹, ⁵², however Amantadine itself has been independently associated with the presence of ICDs (PG, HS, CE and CS) independent of DA or levodopa use. Robust evidence on efficacy is lacking.

There are conflicting reports of benefit from either SSRIs or TCA antidepressants. Conclusive evidence for efficacy is lacking.

Valproate has been reported to improved ICDs but can worsen motor symptoms and cause cognitive deterioration. Zonisamide was found to aid PG, HS, CE and CS in one uncontrolled study without deterioration on UPDRS⁵³. However, evidence again remains inconclusive

Opioid receptor antagonists affecting mu and kappa receptors such as Naltrexone and Nalmefene have shown benefit in some studies in treating compulsive gambling, sexual behaviour, buying and alcoholism in non PD patients⁵⁴, ⁵⁵. A small randomised placebo controlled trial in PD ICDs did not show benefit on the primary endpoint (clinicians rating of symptoms) but did show a statistically significant benefit for naltrexone on a self-report scale for measuring ICD intensity⁵⁶.

Whilst there had been some mixed outcomes with regard to DBS and ICDs previously, the current research suggests DBS may be helpful in ameliorating hyperdopaminergic behaviours,³² in the main part due to reduction in dopaminergic medication. A recent cognitive neuroscience study demonstrated that DBS patients without an ICD were more impulsive in their decision making when their stimulators were turned on. A recent phenomenological study found some patients experiencing self-estrangement due to loss of control and distorted perception of (heightened) capabilities⁵⁷.

CBT has been found to be helpful in some cases compared with waitlist control, however the evidence is limited⁵⁸.

Non-pharmacological interventions⁴⁹ limiting access to money, access to internet (blocking sites), tailoring social interactions, essentially limiting access to opportunities to engage in ICDs can be utilised but require the patient to consent to these limitations on their activities and require either a support network (family/friends) or an MDT of involved professionals, this may include involving local psychiatry teams (CMHT, IHBTT), primary care and social work teams

Non-agreement by the patient may then lead to discussions around capacity and best interest decisions may ensue. Clinicians may feel uncomfortable about capacity decisions in this group of patients for the same complex reasons which are elaborated above when considering the legal aspects of ICDS. However, if there is evidence of harm or potential harm, which can be extremely serious for these patients, then this issue must be approached with an appropriate MDT, patient and family members or friends providing social support. If the patient does not have a social support system in place, an independent mental capacity advocate can be requested.

On-going psychological support will be necessary in assisting the patient to develop increased awareness of behaviours and their consequences, increasing insight, identification of any triggers and the development of strategies to utilise when ‘irresistible urges’ occur. Where there is risk of forensic harm, support and advice could be sought from forensic psychiatry services in developing an appropriate risk management plan.

Clearly to access this kind of support, PD services would be advised to work with these services in developing knowledge of ICDs and identifying what kind of support might be available in managing risks prior to the individual patient need occurring.

Conclusion

Impulse Control Disorders secondary to dopaminergic therapies can have serious consequences. Whilst screening tools are helpful in identifying and assessing certain ICDs, they do not replace the clinical interview and are the starting point rather than the end point in evaluating and managing risk. There is an issue regarding self-reporting. Insight by the patient or reluctance to share the nature or degree of the ICD may lead to low identification of ICDs. Collateral information from carers or other involved professionals is essential in a comprehensive evaluation of risk. Whilst a structured risk assessment is likely to be less targeted to the specific risks dependant on the nature of the ICD, a framework for evaluating and thinking about risk with patient, carers and other professionals involved could enhance practice and more accurately meet the guidance established for monitoring and managing risk outlined in GMC and NICE guidance. It is also more likely to prevent the harmful consequences which can arise as a result of this treatment complication. The framework outlined here takes into account the pre-disposing factors in the development of OCDs; the degree of control and compulsion to act; a detailed analysis of the iCD itself; and a summary of the risks which heed to be managed.

References

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