Some studies revealed attentional impairments in both early and advanced PD (e.g. Brown & Marsden, 1988; Yamada
et al., 1990; Hodgson et al., 1999; Muslimovic et al., 2005; Allcock et al., 2009; Zhou et al., 2012), whereas others did not do so (e.g. Rafal et al., 1984; Lee et al., 1999; Kingstone et al., 2002; Cristinzio et al., 2012). Dopaminergic signals in the striatum and its interaction with the prefrontal cortex would be especially critical in the regulation and integration of higher-level processes, such as attention and cognitive control (Cools, 2011). The first aim of the present study was to examine how dopamine participates in the regulation of attentional PLX3397 order boost by the investigation of patients with PD before and after the administration of dopaminergic medications. We hypothesized that patients with PD receiving dopamine agonists would improve scene recognition performance when scenes are presented with rewarded target letters. Second, we studied the relationship between attentional boost and traditional components of attention (alerting, orienting, executive). Third, we explored the relationship between changes in clinical symptom and psychological trait (motor symptoms, depression, impulsivity) and attentional boost before and after dopamine agonist therapy. Finally, Ku-0059436 we assessed
a separate group of patients with PD receiving L-DOPA medication to test the reproducibility of the results and to examine whether the observed effects are specific for dopamine agonists or not. In the first sample, we recruited 26 newly diagnosed, drug-naive patients with PD and 25 control individuals (acquaintances of hospital staff and non-biological family members of patients matched for age, gender, education and IQ; Table 1). After baseline testing in an unmedicated state, patients received dopamine
agonist therapy and were followed-up for 12 weeks [pramipexole: n = 10, mean dose at follow-up: 4.5 mg/day, range 3.0–6.5 mg/day; ropinirole: n = 10, mean dose at follow-up: 6.0 mg/day, range: 2.5–7.5 mg/day; rotigotine: n = 6; 6 mg/24 h; levodopa equivalent dose (LED): 250 mg/day; Tomlinson et al., 2010]. After selleck screening library the 12-week follow-up period, participants were re-evaluated. In the second sample, we included 15 patients with recent-onset PD receiving L-DOPA monotherapy and 15 matched healthy controls (Table 2). We assessed the second sample only once. The diagnosis of PD was based on the UK Parkinson’s Disease Society Brain Bank Clinical Diagnostic Criteria (Hughes et al., 1992). All participants gave written informed consent prior to their participation. All procedures were approved by the Human Investigation Review Board (protocol number: 2697/2011) in accordance with the declaration of Helsinki (1964). 1.0 : 4 1.5 : 13 2 : 9 1.0 : 1 1.