Josie-Anne Bertrand

Rapid Eye Movement Sleep Behavior Disorder and Risk of Dementia in Parkinson's Disease: A Prospective Study

One of the most devastating nonmotor manifestations of PD is dementia. There are few established predictors of dementia in PD. In numerous cross‐sectional studies, patients with rapid eye movement (REM) sleep behavior disorder (RBD) have increased cognitive impairment on neuropsychological testing, but no prospective studies have assessed whether RBD can predict Parkinsons dementia. PD patients who were free of dementia were enrolled in a prospective follow‐up of a previously published cross‐sectional study. All patients had a polysomnogram at baseline. Over a mean 4‐year follow‐up, the incidence of dementia was assessed in those with or without RBD at baseline using regression analysis, adjusting for age, sex, disease duration, and follow‐up duration. Of 61 eligible patients, 45 (74%) were assessed and 42 were included in a full analysis. Twenty‐seven patients had baseline RBD, and 15 did not. Four years after the initial evaluation, 48% with RBD developed dementia, compared to 0% of those without (P‐adjusted = 0.014). All 13 patients who developed dementia had mild cognitive impairment on baseline examination. Baseline REM sleep atonia loss predicted development of dementia (% tonic REM = 73.2 ± 26.7 with dementia, 40.8 ± 34.5 without; P = 0.029). RBD at baseline also predicted the new development of hallucinations and cognitive fluctuations. In this prospective study, RBD was associated with increased risk of dementia. This indicates that RBD may be a marker of a relatively diffuse, complex subtype of PD.

Mild Cognitive Impairment in Moderate to Severe COPD: A Preliminary Study

BACKGROUND Cognitive impairment is a frequent feature of COPD. However, the proportion of patients with COPD with mild cognitive impairment (MCI) is still unknown, and no screening test has been validated to date for detecting MCI in this population. The goal of this study was to determine the frequency and subtypes of MCI in patients with COPD and to assess the validity of two cognitive screening tests, the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA), in detecting MCI in patients with COPD. METHODS Forty-five patients with moderate to severe COPD and 50 healthy control subjects underwent a comprehensive neuropsychologic assessment using standard MCI criteria. Receiver operating characteristic curves were obtained to assess the validity of the MMSE and the MoCA to detect MCI in patients with COPD. RESULTS MCI was found in 36% of patients with COPD compared with 12% of healthy subjects. Patients with COPD with MCI had mainly the nonamnestic MCI single domain subtype with predominant attention and executive dysfunctions. The optimal MoCA screening cutoff was 26 (≤ 25 indicates impairment, with 81% sensitivity, 72% specificity, and 76% correctly diagnosed). No MMSE cutoff had acceptable validity. CONCLUSIONS In this preliminary study, a substantial proportion of patients with COPD were found to have MCI, a known risk factor for dementia. Longitudinal follow-up on these patients is needed to determine the risk of developing more severe cognitive and functional impairments. Moreover, the MoCA is superior to the MMSE in detecting MCI in patients with COPD.

Color Discrimination Deficits in Parkinson's Disease are Related to Cognitive Impairment and White-Matter Alterations

Color discrimination deficit is a common nonmotor manifestation of Parkinsons disease (PD). However, the pathophysiology of this dysfunction remains poorly understood. Although retinal structure changes found in PD have been suggested to cause color discrimination deficits, the impact of cognitive impairment and cortical alterations remains to be determined. We investigated the contribution of cognitive impairment to color discrimination deficits in PD and correlated them with cortical anomalies. Sixty‐six PD patients without dementia and 20 healthy controls performed the Farnsworth–Munsell 100 hue test and underwent a comprehensive neuropsychological assessment for mild cognitive impairment diagnosis. In a subgroup of 26 PD patients, we also used high‐definition neuroanatomical magnetic resonance imaging for cortical thickness and diffusion tensor analysis. PD patients with mild cognitive impairment performed poorly on the Farnsworth–Munsell 100 hue test compared with PD patients without mild cognitive impairment and controls. In PD patients, performance on the Farnsworth–Munsell 100 hue test was correlated with measures of visuospatial abilities and executive functions. Neuroimaging analysis revealed higher mean and radial diffusivity values in right posterior white‐matter structures that correlated with poor performance on the Farnsworth–Munsell 100 hue test. No cortical thickness correlation reached significance. This study showed that cognitive impairment makes a major contribution to the color discrimination deficits reported in PD. Thus, performance on the Farnsworth–Munsell 100 hue test may reflect cognitive impairment more than color discrimination deficits in PD. Poor performance on the Farnsworth–Munsell 100 hue test was also associated with white‐matter alterations in right posterior brain regions.

An intracranial event-related potential study on transformational apparent motion. Does its neural processing differ from real motion?

How the brain processes visual stimuli has been extensively studied using scalp surface electrodes and magnetic resonance imaging. Using these and other methods, complex gratings have been shown to activate the ventral visual stream, whereas moving stimuli preferentially activate the dorsal stream. In the current study, a first experiment assessed brain activations evoked by complex gratings using intracranial electroencephalography in 10 epileptic patients implanted with subdural electrodes. These stimuli of intermediate levels of complexity were presented in such a way that transformational apparent motion (TAM) was perceived. Responses from both the ventral and the dorsal pathways were obtained. The response characteristics of visual area 4 and the fusiform cortex were of similar amplitudes, suggesting that both ventral areas are recruited for the processing of complex gratings. On the other hand, TAM-induced responses of dorsal pathway areas were relatively noisier and of lower amplitudes, suggesting that TAM does not activate motion-specific structures to the same extent as does real motion. To test this hypothesis, we examined the activity evoked by TAM in comparison to the one produced by real motion in a patient implanted with the same subdural electrodes. Findings demonstrated that neural response to real motion was much stronger than that evoked by TAM, in both the primary visual cortex (V1) and other motion-sensitive areas within the dorsal pathway. These results support the conclusion that apparent motion, even if perceptually similar to real motion, is not processed in a similar manner.

Induced gamma-band response to fragmented images: An intracranial EEG study

Induced gamma-band response (iGBR) has been linked to coherent perception of images and is thought to represent the synchronisation of neuronal populations mediating binding of elements composing the image and the comparisons with memory for proper recognition. This study uses fragmented images with intracranial electroencephalography to investigate the precise spatio-temporal dynamic of iGBR elicited by the recognition of objects presented for the first time and 24h later. Results show an increased iGBR at recognition in regions involved in bottom-up processes such as the cuneus and the lateral occipital complex. Top-down facilitation involved the lingual gyrus, the precuneus and the superior parietal lobule when images were presented for the first time. Twenty-four hours later, top-down facilitation was mediated by frontal areas involved in retrieval from episodic memory. This study showed that the classically reported iGBR is related to object recognition and that top-down processes vary according to task demand.

Recognizing an object from the sum of its parts: An intracranial study on alpha rhythms

Little is known about the relation of alpha rhythms and object recognition. Alpha has been generally proposed to be associated with attention and memory and to be particularly important for the mediation of long-distance communication between neuronal populations. However, how these apply to object recognition is still unclear. This study aimed at describing the spatiotemporal dynamics of alpha rhythms while recognizing fragmented images of objects presented for the first time and presented again 24 hr later. Intracranial electroencephalography was performed in six epileptic patients undergoing presurgical evaluation. Time–frequency analysis revealed a strong alpha activity, mainly of the evoked type, propagating from posterior cerebral areas to anterior regions, which was similar whether the objects were recognized or not. Phase coherence analysis, however, showed clear phase synchronization specific for the moment of recognition. Twenty-four hr later, frontal regions displayed stronger alpha activity and more distributed phase synchronization than when images were presented for the first time. In conclusion, alpha amplitude seems to be related to nonspecific mechanism. Phase coherence analysis suggests a communicational role of alpha activity in object recognition, which may be important for the comparison between bottom–up representations and memory templates.

Mild cognitive impairment in chronic obstructive pulmonary disease

Sylvia Villeneuve, V eronique P epin, Shady Rahayel, Myriam Delorimier, Josie-Anne Bertrand, Catherine Desjardins, JeanFrançois Gagnon, Research Centre, Institut Universitaire de g eriatrie de Montr eal; Research Centre, Hôpital du Sacr e-Coeur de Montr eal; D epartement de psychologie, Universit e de Montr eal, Montreal, Quebec, Canada; 2 Research Centre, Hôpital du Sacr e-Coeur de Montr eal; Department of Exercise Science, Concordia University, Montreal, Quebec, Canada; Research Centre, Hôpital du Sacr e-Coeur de Montr eal; D epartement de psychologie, Universit e de Montr eal, Montreal, Quebec, Canada; 4 Research Centre, Hôpital du Sacr e-Coeur de Montr eal, Montreal, Quebec, Canada; Research Centre, Hôpital du Sacr e-Coeur de Montr eal; D epartement de psychologie, Universit e du Qu ebec a Montr eal, Montreal, Quebec, Canada.