Parkinson's disease is often complicated by psychiatric symptoms. Psychiatrists are caught in a dilemma between such symptoms and physical treatment since Parkinson's disease sometimes shows treatment resistance based on pharmacological treatment-induced dopamine dysfunction. Here, we report on a 64-year-old woman with a 15-year history of Parkinson's disease with stage IV severity based on the Hoehn and Yahr scale. She was admitted to our hospital with a diagnosis of major depressive disorder with psychotic features. Unfortunately, her treatment course for depression was complicated by neuroleptic malignant syndrome. Because we were concerned about the persistence of her depressive symptoms, the risk of psychotropic drugs causing adverse effects, and progressive disuse syndrome, we administered modified electroconvulsive therapy. Her symptoms of neuroleptic malignant syndrome and depression sufficiently improved after five sessions of modified electroconvulsive therapy. Additionally, the primary motor symptoms of her Parkinson's disease also markedly improved. The improvement of neuroleptic malignant syndrome and her motor symptoms based on dopamine dysfunction can be explained by electroconvulsive therapy's effectiveness in activating dopamine neurotransmission. Besides, the marked improvement of her depressive episode with psychotic features was presumed to involve dopamine receptor activation and regulation. Because advanced Parkinson's disease can sometimes be refractory to treatment based on pharmacological treatment-induced dopamine dysfunction, psychiatrists often have difficulty treating psychiatric symptoms; electroconvulsive therapy may stabilize the dopaminergic system in such cases, presenting a possible non-pharmacologic treatment option for Parkinson's disease.

Background: Cognitive decline after oral administration of sedatives, such as benzodiazepines, is a serious side effect. Suvorexant, an orexin receptor antagonist, has a favorable tolerability and a limited side-effect profile. Aim: The purpose of this study was to estimate the cognitive decline 1 day after oral medication with lormetazepam, a benzodiazepine, and suvorexant by comparing mismatch negativity (MMN) and P300 reflecting auditory discrimination function. Methods: Sixty healthy subjects (42 males) were randomly assigned to three groups receiving suvorexant 20 mg, lormetazepam 2 mg, or placebo in this double-blind, randomized control study. Event-related potential recordings during an auditory oddball task and a digit symbol substitution test (DSST) were performed 1 day after oral administration. Results: MMN, on the day after oral administration, was significantly attenuated in the lormetazepam group compared with the other two groups, but there was no difference between the suvorexant and placebo groups. No significant difference was found in P300 amplitudes and DSST scores among the three groups. Conclusion: These findings suggest that suvorexant, unlike benzodiazepine, is not associated with cognitive deficits, as revealed by MMN but not P300. This study shows a neurophysiological difference in the effects of suvorexant and benzodiazepine on cognitive function.

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Speech-sound stimuli have a complex structure, and it is unclear how the brain processes them. An event-related potential (ERP), known as mismatch negativity (MMN), is elicited when an individual's brain detects a rare sound. In this study, MMNs were measured in response to an omitted segment of a complex sound consisting of a Japanese vowel. The results indicated that the latency from onset in the right hemisphere was significantly shorter than that in the frontal midline and left hemispheres during left ear stimulation. Additionally, the results of latency from omission showed that the latency of stimuli omitted in the latter part of the temporal window of integration (TWI) was longer than that of stimuli omitted in the first part of the TWI. The mean peak amplitude was found to be higher in the right hemisphere than in the frontal midline and left hemispheres in response to left ear stimulation. In conclusion, the results of this study suggest that would be incorrect to believe that the stimuli have strictly the characteristics of speech-sound. However. the results of the interaction effect in the latencies from omission were insignificant. These results suggest that the detection time for deviance may not be related to the stimulus ear. However, the type of deviant stimuli on latencies was found to be significant. This is because the detection of the deviants was delayed when a deviation occurred in the latter part of the TWI, regardless of the stimulation of the ear.

The human brain can automatically detect sound changes. Previous studies have reported that rare sounds presented within a sequence of repetitive sounds elicit the mismatch negativity (MMN) in the absence of attention in the latency range of 100–250 ms. On the other hand, a previous study discovered that occasional changes in sound location enhance the middle latency response (MLR) elicited in the latency range of 10–50 ms. Several studies have reported an increase in the amplitude of the MLR within the frame of oddball paradigms such as frequency and location changes. However, few studies have been conducted on paradigms employing a duration change. The purpose of the present study was to examine whether the peak amplitudes of the MLR components are enhanced by a change in duration. Twenty healthy Japanese men (age: 23.9 ± 2.9 years) participated in the present study. We used an oddball paradigm that contained standard stimuli with a duration of 10 ms and deviant stimuli with a duration of 5 ms. The peak amplitudes of the MLR for the deviant stimuli were then compared with those for the standard stimuli. No changes were observed in the peak amplitude of the MLR resulting from a duration change, whereas a definite MMN was elicited. The amplitude of the MLR was increased within the frame of oddball paradigms such as frequency and location changes. By contrast, the amplitude of the MLR was not changed within the duration change oddball paradigm that elicited the MMN.