Displaced center of pressure on the treated side in individuals with essential tremor after radiofrequency ablation: a longitudinal case-control study.

Background: Essential tremor (ET) is a common involuntary movement disorder (IMD). Radiofrequency ablation (RFA) targeting the ventral intermediate nucleus (Vim) of the thalamus is a stereotactic neurosurgery performed in individuals with ET when pharmacotherapy is no longer effective. Though the reasons remain largely unclear, certain adverse events are known to appear post-RFA. These may be due to functional changes in the Vim, related to RFA-induced tremor reduction, or an adverse reaction to compensatory movement patterns used to perform movements in the presence of tremor symptoms. Objective: This study aimed to understand the characteristics of post-RFA symptoms in individuals with ET. Methods: In a longitudinal case-control study, we compared post-RFA symptoms between individuals with ET who underwent Vim-targeted RFA and those with IMD who underwent non-Vim-targeted RFA. Symptoms were compared preoperatively and 1-week and 1-month postoperatively. Quantitative assessments included center-of-pressure (COP) parameters, grip strength, Mini-Mental State Examination, two verbal fluency tests, and three types of physical performance assessments (upper extremity ability, balance ability, and gait ability). Results: Individuals with ET after RFA showed horizontal displacements of the COP to the treated side (the dominant side of the RFA target's hemisphere) at 1-week postoperatively compared to the preoperative period. The horizontal COP displacement was associated with balance dysfunction related to postural stability post-RFA. Other COP parameters did not significantly differ between the ET and IMD groups. Conclusion: COP displacement to the treated side may be due to a time lag in adjusting postural holding strategies to the long-standing lateral difference in tremor symptoms associated with tremor improvement after RFA.

Mirror writing and cortical hypometabolism in Parkinson's disease.

Mirror writing (MW) is the production of individual letters, words, or word strings in the reverse direction. Parkinson's disease (PD) is a progressive neurodegenerative disorder, and high MW rates have been reported in patients with PD. Thus, the present study sought to identify the factors that cause MW in patients with PD. We examined the frequency of MW in patients with PD and investigated the area of the brain where such frequency inversely correlates with reduced regional cerebral metabolic rates of glucose (rCMRglc). We also examined whether this area satisfied the motor and visual monitoring hypotheses of MW that have been presented in previous studies. Thirty-six subjects with idiopathic PD and 23 healthy controls were included in the study. We asked the participants to write down words, numerals, and sentences from left to right using their dominant and non-dominant hands. Patients with PD underwent an 18F-fluorodeoxyglucose positron emission tomography scan to measure the rCMRglc. Neither the patients with PD nor the healthy subjects exhibited MW in the use of the right hand. In the use of the left hand, MW occurred in 15 of the 36 patients with PD, but in none of the healthy controls. The right intraparietal sulcus was identified as the area where rCMRglc was inversely correlated with the number of left-right reversed characters. Previous functional imaging studies have suggested that the right superior parietal cortex and intraparietal sulcus play an important role in recognizing left-right reversed letters. Therefore, dysfunction in the intraparietal sulcus may hinder the recognition of left-right reversed characters, resulting in MW. Consequently, our findings in patients with PD are consistent with the visual-monitoring hypothesis of MW.

Different Impacts of COVID-19 on Quality of Therapy, Psychological Condition, and Work Life Among Occupational Therapists in Physical and Mental Health Fields.

Background: The negative impacts of the coronavirus disease 2019 (COVID-19) pandemic have worsened the quality of therapy, psychological condition, and work life of second-line healthcare workers and occupational therapists (OTs). However, no study has investigated whether the impact of COVID-19 varies among OTs working in different fields. This study aimed to investigate the differences on the impact of COVID-19 between OTs in the physical and mental health fields. Methods: A cross-sectional online survey was conducted in Japan between January 20 and January 25, 2021. A total of 4,418 registered OTs who were members of the Japanese Association of Occupational Therapists volunteered for this study. After screening using the exclusion criteria, 1,383 participants were classified into two groups based on their field (mental health and physical health), and their quality of therapy, psychological condition, and work life were analyzed. Results: OTs in the mental health field showed a greater decrease in therapy quality and increase in workload and a lower rate of decrease in working hours than those in the physical health field. In the multinomial logistic regression analysis, decreased and increased therapy quality and decreased therapy quality were significantly associated with depression in the physical health field, and decreased therapy quality was associated with insomnia in the mental health field. Furthermore, insomnia and anxiety were commonly associated with increased workload and working hours, respectively, in both fields, whereas anxiety and depression were associated with increased workload only in the physical health field. Conclusions: These results demonstrate that COVID-19 differently impacted quality of treatment, workload, work time, and psychological condition in the physical and mental health fields; moreover, the relationships among these are different in these two fields. These results highlight the importance of investigating the field-specific negative impacts of COVID-19 on OTs and may provide helpful information for devising tailored and effective prevention and intervention strategies to address these challenges.

Quality of therapy and mental health among occupational therapists during the COVID-19 pandemic.

Introduction: The coronavirus disease of 2019 (COVID-19) has had a severe psychological impact on occupational therapists. Clarifying the mental health status of occupational therapists and its relationship with therapy quality is essential for maintaining the quality of care and patients' quality of life. Therefore, the present study aimed to investigate whether and how mental health problems are related to the quality of occupational therapy. Methods: A nationwide cross-sectional online survey was conducted during Japan's second national state of emergency (January 2021). A total of 4,418 registered occupational therapists who were members of the Japanese Association of Occupational Therapists participated in this study. After screening for the exclusion criteria, data from 1,966 participants were analyzed. Results: Path analysis showed that insufficient information provision by the workplace and increased workload were associated with depression, anxiety, and insomnia. Specifically, depression was associated with decreased therapy quality. Furthermore, one's therapy quality showed a strong positive correlation with colleagues' therapy quality. Discussion: These results demonstrated a direct link between therapists' mental health conditions and therapy quality and suggested that decreased therapy quality might occur at the institutional rather than individual level. A reassessment of the support system and prompt detection and support for professionals with psychological symptoms may be the key to enhancing therapy quality and patients' quality of life. The present results contribute to the understanding of these relationships, considering the current pandemic context for occupational therapists.

Psychological Impact of COVID-19 on Occupational Therapists: An Online Survey in Japan.

IMPORTANCE: Coronavirus disease 2019 (COVID-19) has had a severe psychological impact on frontline and second-line medical workers. However, few empirical reports have been published on its impact on occupational therapists. Clarifying the mental health status of occupational therapists is important to maintain care quality and prevent psychological problems in this population. OBJECTIVE: To investigate the psychological impact of COVID-19 on Japanese occupational therapists in prefectures with and without severe pandemic-related restrictions and elucidate factors associated with psychological problems such as anxiety, depression, and insomnia. DESIGN: A cross-sectional online survey using region-stratified two-stage cluster sampling conducted May 28-31, 2020. PARTICIPANTS: The sample included 371 participants (63.1% women) in the prefectures under specific cautions (i.e., where residents were strictly advised to refrain from outings) and 1,312 in the prefectures without such cautions (61.9% women). RESULTS: The increase in workload due to the pandemic was significantly related to an increase in anxiety, depression, and insomnia, and an attempt to avoid talking face to face with others was significantly related to an increase in anxiety regardless of area. In prefectures under specific cautions as of May 25, 2020, the provision of sufficient information on COVID-19 by the workplace significantly reduced the risk of insomnia. In other prefectures, the provision of sufficient information significantly reduced the risk of depression. CONCLUSIONS AND RELEVANCE: These results demonstrate the severe negative psychological impact of the increase in workload resulting from COVID-19 and suggest the importance of psychological support for occupational therapists, such as the provision of sufficient information by the workplace. What This Article Adds: This study highlights the importance of providing psychological support for occupational therapists worldwide.

Impaired perception of illusory contours and cortical hypometabolism in patients with Parkinson's disease.

Neuroimaging evidence suggests that areas of the higher-order visual cortex, including the lateral occipital complex (LOC), are engaged in the perception of illusory contours; however, these findings remain unsubstantiated by human lesion data. Therefore, we assessed the presentation time necessary to perceive two types of illusory contours formed by Kanizsa figures or aligned line ends in patients with Parkinson's disease (PD). Additionally, we used 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) to measure regional cerebral glucose metabolism in PD patients. Although there were no significant differences in the stimulus durations required for perception of illusory contours formed by aligned line ends between PD patients and controls, PD patients required significantly longer stimulus durations for the perception of Kanizsa illusory figures. Difficulty in perceiving Kanizsa illusory figures was correlated with hypometabolism in the higher-order visual cortical areas, including the posterior inferior temporal gyrus. These findings indicate an association between dysfunction in the posterior inferior temporal gyrus, a region corresponding to a portion of the LOC, and impaired perception of Kanizsa illusory figures in PD patients.

A Cross-sectional Study of Attention Bias for Facial Expression Stimulation in Patients with Stroke at the Convalescence Stage.

BACKGROUND: Post-stroke depression increases the likelihood of adverse physical symptoms. Attentional bias (AB) for negative stimuli is important in depression onset, maintenance, and remission. Stroke is more likely in older adults, who can have reduced cognitive function. Individuals with mild cognitive impairment (MCI) can have delayed reaction times (RTs). We hypothesized that RT to select neutral facial expression is affected by depressive symptoms and cognitive function in patients with stroke. METHODS: This study analyzed 61 patients with stroke. Beck Depression Inventory-Second Edition (BDI-II) and Profile of Mood States (short version) scores were determined. Task stimuli comprised eight pairs of facial expressions containing affective (angry) and neutral faces. AB was measured as the RT to select the neutral face in two simultaneously presented images using attention bias modification (ABM) software. Patients were grouped according to depressive symptoms using BDI-II scores. Between-subject factors of depressive symptoms and cognitive function were determined by ANCOVA. RESULTS: No significant interaction was found between depressive symptoms and cognitive function on RT. There was a main effect of cognitive function, but not depressive symptoms. In patients with hemiparesis and depressive symptoms, RT was significantly shorter in patients without MCI compared with patients with MCI. CONCLUSIONS: People with stroke and elevated depression symptoms with hemiparesis but without MCI quickly selected neutral facial expressions from neutral and aversive expressions, and thus do not need ABM to escape aversive stimuli. ABM in response to aversive stimuli may be useful in evaluating negative emotions in individuals with post-stroke depression without MCI.

Reproducibility and reliability of performance indicators to evaluate the therapeutic effectiveness of biofeedback therapy after elbow surgery: An observational case series.

Electromyographic biofeedback (EMG-BF) therapy provides information on the state of contraction of the targeted muscles and relaxation of their antagonists, which can facilitate early active range of motion (RoM) after elbow surgery. Our aim in this study was to calculate the minimum detectable change (MDC) during EMG-BF therapy, initiated in the early postoperative period after elbow surgery.This study is an observational case series. EMG-BF of muscle contraction and relaxation was provided during active elbow flexion and extension exercises. Patients completed 3 sets of 10 trials each of flexion and extension over 4 weeks. The total range of flexion-extension motion and scores on the Japanese Society for Surgery of the Hand version of the disability of the arm, shoulder, and hand questionnaire and the Japanese version of the Patient-Rated Elbow Evaluation were obtained at baseline and weekly during the 4-week intervention period. A prediction formula was developed from the time-series data obtained during the intervention period, using the least-squares method. The estimated value was calculated by removing the slope from the prediction formula and adding the initial scores to residuals between the measured scores and predicted scores individually. Systematic error, MDC at the 95th percentile cutoff (MDC95), repeatability of the measures, and the change from the baseline to each time-point of intervention were assessed.The MDC95 was obtained for all 3 outcome measures and the range of values was as follows: RoM, 8.3° to 22.5°; Japanese version of the Patient-Rated Elbow Evaluation score, 17.6 to 30.6 points; and disability of the arm, shoulder, and hand questionnaire subscale: disability and symptoms score, 14.2 to 22.9 points.The efficacy of EMG-BF after elbow surgery was reflected in earlier initiation of elbow RoM after surgery and improvement in patient-reported upper limb function scores. The calculated MDC95 cut-offs could be used as reference values to assess the therapeutic effects of EMG-BF in individuals.

Defining visual illusions in Parkinson's disease: Kinetopsia and object misidentification illusions.

OBJECTIVE: To identify the phenomenological features and neural correlates of visual illusions in Parkinson's disease (PD). METHODS: Ninety-three patients with PD were assessed via questionnaires regarding visual illusions and behavioral symptoms, and neuropsychological tests, motor assessments and 18-F fluorodeoxyglucose-positron emission tomography (FDG-PET) were performed. The relationship between visual illusions or hallucinations and regional cerebral glucose metabolism was investigated using partial least squares (PLS) correlation and conventional mass-univariate analyses. RESULTS: Kinetopsia, in which stationary objects are perceived as being in motion, and object misidentification illusions, in which objects are misperceived as different objects, were the most common types of visual illusions. Kinetopsia and object misidentification illusions were identified in 24 patients (25.8%) and 17 patients (18.3%), respectively. Eleven patients with kinetopsia and 9 patients with object misidentification illusions had visual hallucinations. Kinetopsia and visual hallucinations were associated with hypometabolism in the temporo-parietal cortices, whereas object misidentification illusions were associated with hypometabolism in the early visual cortex, as well as the temporo-parietal cortices. CONCLUSIONS: Our findings suggest that kinetopsia and object misidentification illusions are the most common types of visual illusions in PD. Despite the phenomenological diversity of visual illusions and hallucinations in PD, all of these symptoms are associated with dysfunction of the temporo-parietal cortices, which support visual spatial processing, rather than dysfunction of the ventral temporo-occipital cortices, which supports visual object recognition.

Anxiety, fatigue, and attentional bias toward threat in patients with hematopoietic tumors.

Cancer patients with hematopoietic tumors exhibit particularly high rates of anxiety disorders and depression, and often develop negative affect. In addition, psychological problems experienced by cancer patients impair their quality of life. When cancer patients feel anxious, they tend to direct their attention toward stimuli associated with threat in the surrounding environment. If attentional bias occurs in patients with hematopoietic tumors, who are at particular risk of developing negative affect, resolution of the bias could be useful in alleviating their anxiety. The current study examined the association between attentional bias and negative affect in patients with hematopoietic tumors and tested the hypothesis that negative affect would be more severe in those who exhibited greater attentional bias. Twenty-seven patients with hematopoietic tumors participated in the study. Reaction time (RT) was measured as the time between the presentation of the threatening and neutral images, and the subject's button press to indicate choice (neutral expressions). Eight combinations of "threatening" expressions with high emotional valence and "neutral" expressions with low emotional valence were presented. The images used to measure attentional bias were taken from the Japanese Female Facial Expression Database and had been rated as expressive of anger, sadness, or neutrality, with predetermined emotional valence. Psychological testing was performed with the Profile of Mood States (POMS). To examine the association between attentional bias and negative affect, we calculated Spearman's rank correlation coefficients for RTs and POMS. Subjects' mean RT was 882.9 (SD = 100.9) ms, and 19 of the 27 subjects exhibited slower RTs relative to healthy individuals. RT was significantly positively correlated with Tension-Anxiety (r = .679, p < .01) and Fatigue (r = .585, p < .01) subscale scores. The results of the study suggested that attentional bias toward threatening expressions could be positively correlated with the mental intensity of anxiety and fatigue in patients with hematopoietic tumors.

Neural substrates of cognitive subtypes in Parkinson's disease: a 3-year longitudinal study.

BACKGROUND: The neuropsychological features and neuropathological progression patterns associated with rapidly evolving cognitive decline or dementia in Parkinson's disease (PD) remain to be elucidated. METHODS: Fifty-three PD patients without dementia were recruited to participate in a 3-year longitudinal cohort study. The patients were grouped according to the Clinical Dementia Rating (CDR). Group-wise comparisons were made with regard to demographic characteristics, motor symptoms, neuropsychological performances and 18F-fluorodeoxyglucose positron emission tomography. RESULTS: Patients who had memory-plus cognitive impairment (patients whose CDR was 0 at baseline and 0.5 in memory and other domains at follow-up, and those whose baseline CDR was 0.5 in memory and other domains) exhibited higher age at onset, visuoperceptual impairment, non-tremor-dominant motor disturbance, rapid symptomatic progression and posterior neocortical hypometabolism. In patients who were cognitively unimpaired and those who had memory-dominant cognitive impairment (patients whose CDR was 0 at baseline and 0.5 only in memory domain at follow-up, and those whose baseline CDR was 0.5 only in memory domain), the posterior neocortex was relatively unaffected until a later stage of the disease. CONCLUSIONS: These results suggest that visuoperceptual impairment and the early involvement of the posterior neocortex may be risk factors for rapid symptomatic progression and dementia in PD.

Hypometabolism in the supplementary and anterior cingulate cortices is related to dysphagia in Parkinson's disease: a cross-sectional and 3-year longitudinal cohort study.

OBJECTIVE: Dysphagia is one of the cardinal symptoms of Parkinson's disease (PD). It is closely related to the quality of life and longevity of PD patients. The aim of the study is to clarify the pathophysiological mechanisms responsible for dysphagia in PD. DESIGN: A cross-sectional and longitudinal comparative study. SETTING: Tohoku University Hospital. PARTICIPANTS: Eight patients with dysphagia, 15 patients without dysphagia and 10 normal control subjects. MAIN OUTCOME MEASURES: The time needed for swallowing initiation and changes in brain glucose metabolism at baseline and after a 3-year follow-up period. RESULTS: The time needed for swallowing initiation was significantly longer in the patients with dysphagia compared with the patients without dysphagia at baseline and after the 3-year follow-up period (p<0.05). The patients with dysphagia exhibited hypometabolism in the supplementary motor area (SMA) and the anterior cingulate cortex (ACC) compared with the 10 normal control subjects at baseline (uncorrected p<0.001). After the 3-year follow-up period, the number of brain areas showing hypometabolism increased, involving not only the SMA and the ACC but also the bilateral medial frontal lobes, middle cingulate cortex, thalamus and right superior, middle, inferior and orbital frontal gyri (uncorrected p<0.001). In contrast, the patients without dysphagia showed virtually no regional hypometabolism at baseline (uncorrected p<0.001) and only a small degree of hypometabolism in the SMA and ACC after the 3-year follow-up period (uncorrected p<0.001). CONCLUSIONS: These results suggest that dysphagia in PD patients is mainly related to a difficulty in swallowing initiation that is based on a combination of poor movement planning due to SMA dysfunction and impaired cognitive processing due to ACC dysfunction.

Attentional set-shifting deficit in Parkinson's disease is associated with prefrontal dysfunction: an FDG-PET study.

The attentional set-shifting deficit that has been observed in Parkinson's disease (PD) has long been considered neuropsychological evidence of the involvement of meso-prefrontal and prefrontal-striatal circuits in cognitive flexibility. However, recent studies have suggested that non-dopaminergic, posterior cortical pathologies may also contribute to this deficit. Although several neuroimaging studies have addressed this issue, the results of these studies were confounded by the use of tasks that required other cognitive processes in addition to set-shifting, such as rule learning and working memory. In this study, we attempted to identify the neural correlates of the attentional set-shifting deficit in PD using a compound letter task and 18F-fluoro-deoxy-glucose (FDG) positron emission tomography during rest. Shift cost, which is a measure of attentional set-shifting ability, was significantly correlated with hypometabolism in the right dorsolateral prefrontal cortex, including the putative human frontal eye field. Our results provide direct evidence that dysfunction in the dorsolateral prefrontal cortex makes a primary contribution to the attentional set-shifting deficit that has been observed in PD patients.

Illusory misidentifications and cortical hypometabolism in Parkinson's disease.

Idiopathic Parkinson's disease (PD) is associated with documented impairments in various visual functions. However, there have been only a limited number of studies that have reported on the brain regions responsible for impairment of visual recognition in PD. In our study, we evaluated the performance of PD patients and 24 healthy controls on the Poppelreuter-type overlapping figure identification test to investigate the impairment of visual recognition. We also measured the PD patients' resting cerebral glucose metabolism using (18) F-fluorodeoxyglucose positron emission tomography and investigated the relationship between the impairment of visual recognition and cortical hypometabolism. The PD patients had substantial and frequent illusory responses in the overlapping figure identification test, and their illusory misidentifications were correlated with hypometabolism in the visual cortices, including the right inferior temporal gyrus and the bilateral temporo-parieto-occipital junction. These findings suggest that PD patients have impaired visual recognition characterized by illusory misidentifications of visual stimuli, which could be attributed to dysfunction of the visual cortices.

Neural substrates for writing impairments in Japanese patients with mild Alzheimer's disease: a SPECT study.

Language is fairly well preserved in most patients with mild Alzheimer's disease, but writing ability seems to be impaired even in the early stages of the disease. To investigate the neural bases of writing impairments in Alzheimer's disease (AD), we examined the correlation between writing ability and regional cerebral blood flow (rCBF) in 52 Japanese patients with mild AD compared to 22 controls, using single photon emission computed tomography (SPECT). We found that, compared with control subjects, Kana writing to dictation and copying Kanji words were preserved in AD patients, but writing to dictating Kanji words was impaired. We classified the errors in the Kanji dictation task into four types to investigate the correlation between rCBF and the error type, as follows: non-response errors, phonologically plausible errors, non-phonologically plausible errors, and peripheral errors. Non-response errors, which indicated difficulty with retrieving Kanji graphic images, were the most frequent. When controlled for confounding factors, the number of non-response errors negatively correlated with rCBF in the left inferior parietal lobule, the posterior middle and inferior temporal gyri, and the posterior middle frontal gyrus. Thus, the impaired recall of Kanji in early Alzheimer's disease is related to dysfunctional cortical activity, which appears to be predominant in the left frontal, parietal, and temporal regions.

[Pathophysiological process underlying Parkinson's disease: motor & non-motor symptoms].

It is proposed that alpha-synucleinopathy initially affects the medulla oblongata and then progresses to more rostral brain areas ("Braak hypothesis"). According to this hypothesis, substantia nigra is affected in the later stages of PD. Another region affected in the earlier stages was reported to be olfactory bulb, although the following processes were not described in detail. On the other hand, several lines of evidence suggest that non-motor symptoms including constipation, depression, REM-sleep behavior disorder (RBD) and hyposmia may be prodromal symptoms in PD. The pathological staging postulated by the Braak hypothesis is in good agreement with the fact that these non-motor symptoms precede motor symptoms in PD, because affected brain areas in the early stages, such as dorsal vagal nucleus, locus ceruleus and olfactory bulb, are related to these non-motor features. Recently, it was reported that although half of brains corresponded to the Braak hypothesis, there were a high proportion of cases which did not fit the Braak's staging system and majority of the latter demonstrated amygdale-predominant alpha-synucleinopathy. It was also demonstrated that the Lewy pathology in olfactory bulb was closely related to the presence of alpha-synuclein pathology in amygdala. The amygdala is one of the main systems in odor perception and in PD, cortical neurons in corticomedial complex of amygdale, which have major olfactory connections, are selectively affected even in the early stages of the disease. We recently obtained the data suggesting that metabolic changes in the amygdala were associated with low scores in odor identification test. These data suggest that not only the olfactory bulb, but also the amygdala is also responsible for hyposmia in PD and that there may be another pathological process, which starts from the olfactory bulb and involves the amygdala.

Do parkinsonian patients have trouble telling lies? The neurobiological basis of deceptive behaviour.

Parkinson's disease is a common neurodegenerative disorder with both motor symptoms and cognitive deficits such as executive dysfunction. Over the past 100 years, a growing body of literature has suggested that patients with Parkinson's disease have characteristic personality traits such as industriousness, seriousness and inflexibility. They have also been described as 'honest', indicating that they have a tendency not to deceive others. However, these personality traits may actually be associated with dysfunction of specific brain regions affected by the disease. In the present study, we show that patients with Parkinson's disease are indeed 'honest', and that this personality trait might be derived from dysfunction of the prefrontal cortex. Using a novel cognitive task, we confirmed that patients with Parkinson's disease (n = 32) had difficulty making deceptive responses relative to healthy controls (n = 20). Also, using resting-state (18)F-fluorodeoxyglucose PET, we showed that this difficulty was significantly correlated with prefrontal hypometabolism. Our results are the first to demonstrate that the ostensible honesty found in patients with Parkinson's disease has a neurobiological basis, and they provide direct neuropsychological evidence of the brain mechanisms crucial for human deceptive behaviour.

Distinct patterns of regional cerebral glucose metabolism in Parkinson's disease with and without mild cognitive impairment.

There is no consensus with regard to the clinical and neuroimaging characteristics of prodromal dementia in Parkinson's disease (PD). To delineate functional neuroimaging features of PD with mild cognitive impairment (PDMCI) and with no cognitive impairment (PDNC), we compared regional cerebral glucose metabolism (CMRglc) amongst 13 patients with PDMCI, 27 with PDNC, and 13 healthy controls. The PDNC patients had limited areas of hypometabolism in the frontal and occipital cortices. In the PDMCI patients, there were extensive areas of hypometabolism in the posterior cortical regions, including the temporo-parieto-occipital junction, medial parietal, and inferior temporal cortices. The present results suggest that posterior cortical dysfunction is the primary neuroimaging feature of PD patients at risk for dementia.

[Impairment in visual cognition in patients with Parkinson disease].

Neural pathway for visual information processing involves retina, lateral geniculate body, primary visual cortex, and higher visual cortical areas, all of which have been reported to be disordered either functionally or pathologically in Parkinson disease (PD). As elementary visual disorders, there have been studies that reported reduced contrast sensitivity for middle to high spatial frequencies and impaired blue color perception. Most of those studies suggested retina as the damaged cite that is responsible for the impairments, whereas some studies pointed to the possible cortical involvement. Impairments of higher visual functions also have been reported. In the dorsal stream, impairments of object localization, depth perception, and mental rotation have been reported. In the ventral stream, object perception and visual integration of objects have been found to be impaired. A meta-analysis study, however, concluded that although there may be impairments in higher order functions like attention and problem solving capacity there is no firm evidence for the impairments of higher visual functions. Neuroimaging studies have found a relationship between reduced metabolism centered in the parietal lobe and impaired performance in higher visual functions. Impaired identification of overlapping figures has been reported in dementia with Lewy bodies a disease that is akin to PD. Capacity to discriminate textured areas has been found to be damaged in PD. We conducted a FDG-PET study to explore the relationship between brain metabolism and perception of overlapping figures, perception of shapes defined by texture differences and perception of subjective contours in PD. It revealed that there is a correlation between reduced activation in lateral occipital complex and impaired performance for these tasks, suggesting some compromised ventral rout functions.