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Objective-To examine the hypothesis that apathy is a core feature of Parkinson disease (PD) and that apathy can be dissociated from depression. Methods-Eighty patients with PD and 20 patients with dystonia completed depression and apathy measures including the Marin Apathy Evaluation Scale (AES), Beck Depression Inventory (BDI), and Centers for Epidemiologic Studies-Depression Scale (CES-D).Results-There was a significantly higher severity and frequency of apathy in PD (frequency = 51%, 41/80) than in dystonia (frequency = 20%, 4/20). Apathy in the absence of depression was frequent in PD and did not occur in dystonia (PD = 28.8%, dystonia = 0%). Conclusions-Patients withParkinson disease (PD) experienced significantly higher frequency and severity of apathy when compared with patients with dystonia. Apathy may be a "core" feature of PD and occurs in the absence of depression.Recent attention has focused on a "syndrome of apathy": a primary loss of motivation, loss of interest, and loss of effortful behavior. 1,2 It has been proposed that apathy can manifest in neurologic disorders as both a symptom and a syndrome. 3 Specific diagnostic criteria for a syndrome of apathy include a primary lack of motivation that manifests itself in three domains. The behavioral domain includes lack of effort, lack of productivity, and dependence on others to structure activities. The cognitive domain includes loss of interest in new experience and lack of concern about one's problems. The affective domain includes flattened affect and lack of response to positive or negative events. Emphasized is the primary lack of motivation that is not purely accounted for by intellectual impairment, emotional distress, or diminished consciousness such as drowsiness or delirium. 3 However, it remains unclear whether apathy is a distinct syndrome or merely a symptom of depression. Depressed patients often have symptoms of apathy. Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) criteria for a major depressive episode demand at least five symptoms and require either a depressed mood or a markedly diminished interest or pleasure in activities. Loss of interest is also a cognitive symptom of apathy. Thus, depression includes symptoms of apathy. However, it has been suggested that apathy can occur in the absence of depression, and depression can occur in the absence of apathy. 2 At least six studies have investigated apathy in PD. 1,2,4-7 Several used informant-based rating scales. Because motivation is an internal state that may be difficult for informants to assess accurately, especially given the difficulties patients with PD have in expressing emotions (e.g., "masked facies"). It may be more accurate to allow patients with PD to answer questions. Other studies did not use a movement disorder control group. Without such, there is no way to know if rates of apathy are uniquely higher in PD. Comparison with another subcortical disorder would be a strong test of whether apathy is a "core feature" of PD. Therefore, w...

Rationale Dopaminergic medication-related Impulse Control Disorders (ICDs) such as pathological gambling and compulsive shopping have been reported in Parkinson disease (PD). Hypothesis We hypothesized that dopamine agonists (DAs) would be associated with greater impulsive choice, or greater discounting of delayed rewards, in PD patients with ICDs (PDI). Methods Fourteen PDI patients, 14 PD controls without ICDs and 16 medication-free matched normal controls were tested on (i) the Experiential Discounting Task (EDT), a feedback-based intertemporal choice task, (ii) spatial working memory and (iii) attentional set shifting. The EDT was used to assess impulsivity choice (hyperbolic K-value), reaction time (RT) and decision conflict RT (the RT difference between high conflict and low conflict choices). PDI patients and PD controls were tested on and off DA. Results On the EDT, there was a group by medication interaction effect [F(1,26)=5.62; p=0.03] with pairwise analyses demonstrating that DA status was associated with increased impulsive choice in PDI patients (p=0.02) but not in PD controls (p=0.37). PDI patients also had faster RT compared to PD controls F(1,26)=7.51 p=0.01]. DA status was associated with shorter RT [F(3,24)=8.39, p=0.001] and decision conflict RT [F(1,26)=6.16, p=0.02] in PDI patients but not in PD controls. There were no correlations between different measures of impulsivity. PDI patients on DA had greater spatial working memory impairments compared to PD controls on DA (t=2.13, df=26, p=0.04). Conclusion Greater impulsive choice, faster RT, faster decision conflict RT and executive dysfunction may contribute to ICDs in PD.

Impulse control disorders are common in Parkinson's disease, occurring in 13.6% of patients. Using a pharmacological manipulation and a novel risk taking task while performing functional magnetic resonance imaging, we investigated the relationship between dopamine agonists and risk taking in patients with Parkinson's disease with and without impulse control disorders. During functional magnetic resonance imaging, subjects chose between two choices of equal expected value: a 'Sure' choice and a 'Gamble' choice of moderate risk. To commence each trial, in the 'Gain' condition, individuals started at $0 and in the 'Loss' condition individuals started at -$50 below the 'Sure' amount. The difference between the maximum and minimum outcomes from each gamble (i.e. range) was used as an index of risk ('Gamble Risk'). Sixteen healthy volunteers were behaviourally tested. Fourteen impulse control disorder (problem gambling or compulsive shopping) and 14 matched Parkinson's disease controls were tested ON and OFF dopamine agonists. Patients with impulse control disorder made more risky choices in the 'Gain' relative to the 'Loss' condition along with decreased orbitofrontal cortex and anterior cingulate activity, with the opposite observed in Parkinson's disease controls. In patients with impulse control disorder, dopamine agonists were associated with enhanced sensitivity to risk along with decreased ventral striatal activity again with the opposite in Parkinson's disease controls. Patients with impulse control disorder appear to have a bias towards risky choices independent of the effect of loss aversion. Dopamine agonists enhance sensitivity to risk in patients with impulse control disorder possibly by impairing risk evaluation in the striatum. Our results provide a potential explanation of why dopamine agonists may lead to an unconscious bias towards risk in susceptible individuals.

Background-The Parkinson's Progression Markers Initiative (PPMI) is an ongoing observational, longitudinal cohort study of participants with Parkinson's disease, healthy controls, and carriers of the most common Parkinson's disease-related genetic mutations, which aims to define biomarkers of Parkinson's disease diagnosis and progression. All participants are assessed annually with a battery of motor and non-motor scales, 123-I Ioflupane dopamine transporter (DAT) imaging, and biological variables. We aimed to examine whether non-manifesting carriers of LRRK2 and GBA mutations have prodromal features of Parkinson's disease that correlate with reduced DAT binding.