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Objective : Auditory P300 has been reported to be abnormal in demented patients with Parkinson's disease. However, it is still controversial which factors in Parkinson's disease influence P300 parameters. Methods : Forty patients with Parkinson's disease were included. Patients were divided into two groups: patients with dementia (PDD) and without dementia (PDND). An ‘odd-ball’ paradigm was used for auditory event-related potentials. Results : P300 latency was markedly delayed in PDD patients. Age and DRS1 (attention) were the most important factors influencing P300 latency. Conclusions : Although there have been reports of P300 in the past, its abnormalities reflect the deficit of attention in Parkinson's disease.

Background Few imaging studies investigated frontal dysfunctions in Parkinson's disease. Objectives We investigated relationships between Wisconsin Card Sorting Test (WCST) and brain perfusion in patients with non-demented Parkinson's disease. Methods Patients were divided into two groups according to WCST score: (1) CA (number of category achieved)≤2 or (2) CA≥3. We performed three-dimensional stereotactic surface projection and volume of interest analysis using 123I-IMP scintigraphy. Results Hypoperfusions of the bilateral posterior cingulate, rostrodorsal prefrontal, and left frontopolar cortices were shown in CA≤2 group, with the left cingulate and right rostrodorsal prefrontal cortices showing prominent hypoperfusion. CA and PE (perseverative errors) scores significantly correlated with perfusion of the left posterior cingulate cortex. PE score also correlated with perfusion of the right rostrodorsal prefrontal cortex. Conclusion Data indicated participations of various regions in task achievement. Careful interpretation of WCST scores is required.

Background Although excessive daytime sleepiness (EDS) in Parkinson's disease (PD) has received a great deal of attention, the underlying pathological mechanism of its development and the relative contributions of brain function to this process are poorly understood. Objective To compare the fractional anisotropy (FA) values of PD patients with EDS and those without EDS, and to investigate the mechanism of EDS in this disease. Methods Eleven patients with PD with EDS, 26 patients with PD without EDS and 10 controls participated in this study. Patients with an ESS (Epworth Sleepiness Scale) score ≥10 were defined as having EDS. The FA values of 5 regions of interest (ROI) including the fornix were compared between the three groups. Results There were significant reductions in FA values of the fornix fiber in patients with EDS. ESS scores had significant correlation with FA values of the fornix. Conclusions Our study is the first to find the fornix fiber degeneration in PD patients with EDS. These results indicate that fornix dysfunction may have some correlations with EDS in PD.

Catalepsy is a generalized condition of diminished responsiveness shown by a trance-like state, posturing, or maintenance of physical positions for a prolonged period of time. It is an internal reaction to escape from stress and one of the characteristic symptoms of catatonia. Interactions among various neurotransmitters such as dopamine, serotonin, and γ-aminobutyric acid (GABA) are involved in the onset of catalepsy, but the mechanism has not yet been completely elucidated. An 87-year-old man with Parkinson's disease on l- dopa therapy showed catalepsy. Eight years after the onset, he developed episodes of akinetic mutism with catalepsy, which gradually became prolonged. He became almost unable to take oral medication, so was admitted to our department, where intravenous l -dopa injection therapy was started. At 20 min after l -dopa injection, catalepsy was evoked. Suspecting that l -dopa was involved in catalepsy, we reduced the dose. With a reduction in l -dopa, the frequency of akinetic mutism with catalepsy decreased. In addition, single-photon emission computed tomography (SPECT) with three-dimensional stereotactic surface projection (3D-SSP) demonstrated decreased cerebral blood perfusion in the prefrontal cortex and increased perfusion in the motor cortex. Some reports have shown that stress can increase dopamine release in the medial prefrontal cortex, and excessive dopamine causes dopamine receptor down-regulation. In this case, besides chronic stress, l -dopa was a factor in causing excessive dopamine in the prefrontal cortex. Moreover, increased perfusion in the motor cortex is suspected of being associated with continuous movement. Some reports have shown that various modulations originate in the prefrontal cortex and affect the motor area, and that disturbance of such modulation is involved in the onset of catalepsy. In conclusion, we speculate that stress and l -dopa caused the down-regulation of dopamine receptors in the prefrontal cortex and subsequent dysfunction of this area. As a result, modulation originating in the prefrontal cortex and affecting the motor area did not function appropriately.