ABSTRACT
Previous studies on inhibitory mechanisms assessed by negative priming (NP) paradigms in patients suffering from Parkinson's disease (PD) have yielded highly ambiguous results. The present study examined two possible reasons for this heterogeneity: general slowing and anti-Parkinsonian medication. Their effects on identity and location NP and positive priming (PP) were investigated. Twenty medicated PD patients and 20 PD patients after drug withdrawal were compared to 20 sex- and age-matched healthy controls. The influence of PD patients' general slowing on priming effects was statistically controlled. Location NP was found not to be affected by PD, whereas identity NP was reduced in medicated PD patients compared to non-medicated PD patients and healthy controls. At first, identity and location PP appeared to be enhanced in both PD groups. After controlling for general slowing, however, differences between PD patients and healthy controls disappeared. These findings endorse the notion that uncontrolled effects of both, PD-related general slowing and anti-Parkinsonian medication may have contributed to previously conflicting results on priming effects in PD patients.
Subject(s)
Antiparkinson Agents/therapeutic use , Identification, Psychological , Inhibition, Psychological , Parkinson Disease/drug therapy , Parkinson Disease/physiopathology , Reaction Time/physiology , Analysis of Variance , Antiparkinson Agents/pharmacology , Attention/drug effects , Attention/physiology , Female , Humans , Neuropsychological Tests , Paired-Associate Learning/drug effects , Paired-Associate Learning/physiology , Pattern Recognition, Visual/drug effects , Pattern Recognition, Visual/physiology , Photic Stimulation/methods , Reaction Time/drug effectsABSTRACT
Mechanisms of selective attention are frequently reported to be impaired in Parkinson's disease (PD). Fundamental to selective attention is attending to relevant information and, concurrently, ignoring irrelevant information. Both processes can be assessed by positive priming (PP) and negative priming (NP) tasks, respectively. Unlike previous studies, in the present experiment, two separate identity- and location-based priming tasks were applied to 48 PD patients and 48 sex- and age-matched healthy controls. Results indicated that identity and location PP were reliably enhanced in PD patients compared to controls. Both groups showed significant location NP of almost identical magnitude but no identity NP. However, there was evidence for a positive functional relationship between severity of bradykinesia and identity NP. Furthermore, with increasing depression scores, location NP was enhanced in PD patients but not in controls. These findings suggest that disturbed selective attention associated with PD is due to changed mechanisms mediating attention to relevant information rather than due to mechanisms involved in inhibition of irrelevant information.
