Biomedical subjects

A Décary

Publications and source records attributed to A Décary.

9 recordsLinked to original sources

PubMed2004

Association between waking EEG slowing and REM sleep behavior disorder in PD without dementia.

OBJECTIVE: To compare nondemented patients with Parkinson's disease (PD) with and without REM sleep behavior disorder (RBD) to healthy controls on quantitative EEG characteristics for both wakefulness and REM sleep. METHODS: Fifteen patients with PD (7 patients with polysomnographic-confirmed RBD [PD-RBD] and 8 patients without RBD [PD-NRBD]) and 15 healthy control subjects were studied. Each subject underwent a quantitative EEG analysis of both wakefulness and REM sleep. RESULTS: During wakefulness, patients with PD-RBD showed a higher theta power in frontal, parietal, temporal, and occipital regions in comparison to patients with PD-NRBD and control subjects. Moreover, a slowing of the dominant occipital frequency was observed only in patients with PD-RBD (p < 0.02). Patients with PD-NRBD did not present any slowing of the EEG. No between-group difference in quantitative REM sleep EEG was observed. CONCLUSIONS: This study demonstrates that the EEG slowing reported during wakefulness in nondemented patients with PD is strongly related to the presence of RBD.

Aged↗

PubMed2001

Daytime sleepiness and EEG spectral analysis in apneic patients before and after treatment with continuous positive airway pressure.

BACKGROUND: Obstructive sleep apnea syndrome (OSAS) is characterized by recurrent apneas during sleep, resulting in repetitive hypoxemic episodes and interruptions of the normal sleep pattern. A previous study showed EEG slowing (ie, a higher ratio of delta + theta frequencies to alpha + beta frequencies on EEG) during rapid eye movement (REM) sleep and wakefulness in untreated OSAS patients. STUDY AND OBJECTIVES: To determine whether EEG slowing is reversible with continuous positive air pressure (CPAP) treatment and to verify whether the persistence of excessive daytime sleepiness (EDS) is correlated with residual slowing of the EEG. PATIENTS: Ten healthy subjects (9 men and 1 woman) and 14 patients with moderate-to-severe OSAS (13 men and 1 woman) were studied before and after 6 months of treatment with CPAP. RESULTS: Untreated OSAS patients showed EEG slowing in frontal and central cortical regions during both wakefulness and during REM sleep compared to healthy control subjects. This EEG slowing was found to be independent of time spent with arterial oxygen saturation < 90%, severity of OSAS, or mean sleep latency as determined by the multiple sleep latency test. CPAP treatment was found to correct the EEG slowing for both REM sleep and wakefulness. Daytime sleepiness also greatly improved with treatment, but some degree of somnolence remained. CONCLUSION: CPAP treatment was found to correct the EEG slowing that was observed in untreated OSAS patients. Persistent EDS may be related to persistent obesity after CPAP treatment.

Adult↗

PubMed2001

Slow-wave activity in sleep apnea patients before and after continuous positive airway pressure treatment: contribution to daytime sleepiness.

STUDY OBJECTIVES: To estimate the course of slow-wave activity (SWA), its amount during the night, and its correlation with daytime sleepiness in sleep apnea syndrome (SAS) patients. This study also verified whether continuous positive airway pressure (CPAP) treatment also restores a normal pattern of SWA in severe SAS patients. PARTICIPANTS: Ten patients with a diagnosis of severe SAS who showed a good clinical response to CPAP after approximately 9 months of treatment were included in this study. These patients were matched for sex and age with 10 control subjects. DESIGN: All subjects underwent 1 night of polysomnography (PSG), followed by the multiple sleep latency test (MSLT) the next day. For the SAS patients only, the same procedure was repeated after 9 +/- 0.7 months of CPAP treatment. In addition to traditional scoring of sleep stages, apneas, hypopneas, and microarousals, the SWA, defined as the power in the 0.75- to 4.5-Hz frequency band, was evaluated. RESULTS: A positive correlation between SWA of the first cycle and the MSLT (r = 0.56; p = 0.045) was found before treatment. Moreover, SAS patients significantly increased their mean SWA after CPAP treatment in the first (p = 0.024) and second (p = 0.002) sleep cycles and restored a more physiologic decay of SWA across the night. CONCLUSIONS: These results suggest that daytime sleepiness in SAS patients may be the result of a lack of SWA during the first part of the night, and show that CPAP restores a more physiologic pattern of SWA across the night.

Adult↗

PubMed2000

Cognitive deficits associated with sleep apnea syndrome: a proposed neuropsychological test battery.

Numerous studies have assessed a wide range of cognitive deficits associated with obstructive sleep apnea syndrome (OSAS). The comparison of these various results, however, is hampered by the fact that different studies employ different neuropsychological tests, even when assessing the same function. The aim of this paper is to present a standardized neuropsychological test battery for the evaluation of OSAS patients. Following a description of the general characteristics of OSAS, we review the main cognitive functions reported as being impaired in OSAS patients. These include general intellectual functioning, attentional functioning, memory and learning abilities, executive functions, and motor performance. Based on this review, we propose a test battery designed to cover these cognitive processes while taking into account the time constraints present in most research and clinical centers. In addition to providing a comprehensive neuropsychological evaluation of OSAS patients, the proposed test battery should facilitate the comparison of results from different laboratories.

Adolescent↗

PubMed1998

Sleep disturbances and eeg slowing in alzheimer's disease.

Changes in sleep structure, and especially REM sleep, and in EEG activation were studied in relation to the cholinergic deficit found in Alzheimer's Disease (AD). With respect to sleep architecture, only REM sleep percent was reduced in AD patients compared to controls as a result of a decrease in mean REM episode duration. Different results were obtained in patients with progressive supranuclear palsy (PSP). These results are discussed with respect to the role of brainstem and forebrain cholinergic populations in REM sleep generation in humans. More importantly, it was shown by means of spectral analyses that EEG slowing is much more prominent in REM sleep than in wakefulness in AD. Furthermore, there is a distinct topographical pattern of REM sleep EEG slowing in AD patients which is in agreement with findings from neuroradiological and neuropathological studies. Using the ratio of slow over fast frequencies from the temporal regions, a correct classification of 90.4% of subjects was obtained for the REM sleep EEG. This discrimination rate is the best marker of AD so far using a single measure. Quantitative REM sleep EEG was also used to evaluate patients' biological response to cholinergic treatments. Finally, we present here preliminary data on the progression of EEG slowing in wakefulness and in REM sleep. After six months on a placebo, there was only a decrease in alpha activity in wakefulness over all regions studied. No changes were observed for REM sleep.

Aged↗

PubMed1997

Sleep and quantitative EEG in patients with progressive supranuclear palsy.

Sleep architecture and quantitative EEG from wakefulness and REM sleep were studied in six patients (mean age, 70.5 years) with progressive supranuclear palsy (PSP) and compared with that of six control subjects (mean age, 69.8 years). Particular attention was given to quantifying REM sleep variables because of the known PSP-associated degeneration of the pedunculopontine tegmentum (PPT)--a critical structure in REM sleep generation. Patients with PSP had a shorter total sleep time, a lower sleep efficiency, a drastic reduction in sleep spindles, an atonic slow-wave sleep, and a lower percentage of REM sleep. The lower percentage of REM sleep was the result of both a reduction in the number of REM periods and a reduction in mean period of duration. REM density was also reduced while REM efficiency, atonia, and phasic EMG were similar to control values. REM sleep findings are consistent with the known role of the PPT in REM sleep induction. A slowing of the awake EEG was found for the six frontal leads and for C4, P4, and T4 in PSP patients. The frontal EEG slowing found in wakefulness is in accord with imaging and neuropsychological studies showing impairment of the frontal lobes in these patients. REM sleep EEG was not significantly slower in any regions. Because all previous studies on PSP have relied on visual inspection of the EEG tracings, the present finding of EEG slowing in the frontal lobes (rather than in the temporal regions or diffusely) suggests that our quantitative EEG approach may be more useful in determining specific regions of impaired cortical activity.

Aged↗

PubMed1995

Response selection deficits in frontal excisions.

We compared the performance of patients with frontal excisions, patients with temporal excisions and controls in tasks involving speeded choice responses in which a number of variables were manipulated including: perceptual difficulty, stimulus and response set-size, associative complexity, and spatial stimulus-response compatibility. Response times were sensitive to all manipulations but did not show any group differences. The error rates of the three groups were equally affected by perceptual difficulty and response set-size but frontals were preferentially affected by spatial S-R compatibility, associative complexity, and the number of stimuli per response. The results are consistent with a basic deficit in response selection processes which could underly many problems produced by frontal lesions.

Adult↗

PubMed1993

Target detection deficits in frontal lobectomy.

We examined the hypothesis of dorsomedial frontal lobe involvement in target detection through the effects of distractor interference and multiple target interference on unilateral lobectomy patients. Seven patients who underwent a unilateral frontal lobectomy for epilepsy involving dorsomedial cortex and variable amounts of lateral cortex were compared to 10 patients with a unilateral temporal lobectomy and to 10 normal adults on a visual character cancellation task. The task involved detecting occurrences of target characters embedded in rows of characters under three conditions: detection of one target character in the absence of distractors, detection of one target character among distractors, and detection of three targets among distractors. Visual detection performance was compared to that in the Stroop reading interference task. Frontals were predictably slower than the other groups in the baseline conditions of the character cancellation task and the Stroop task. After partialing out baseline detection performance in the character cancellation task, frontals showed an almost normal detection in the presence of distractors but were distinctly slower and made more errors than the other groups in multiple target detection. Frontals were also slower on the Stroop even after partialing out baseline naming performance. Temporals were normal on all tasks. Results suggest that frontal damage can affect selectivity in target detection as well as the Stroop and that this deficit is independent of the general psychomotor slowing observed in these patients.

Adolescent↗

PubMed1993

Tardive dyskinesia and associated cognitive disorders: a convergent neuropsychological and neurophysiological approach.

This study sought to assess whether tardive dyskinesia (TD) related differentially to two types of cognitive functioning in schizophrenia. Thirteen schizophrenics with severe formal thought disorders (+FTD) were matched for age, sex, education, chronicity, dosage, hospital care, with 13 schizophrenics selected for absence of or minimal formal thought disorders (-FTD). TD and neuroleptic dosage were analyzed in relation to cognitive and motor tests of the Luria-Nebraska (L-N) battery and to attentional evoked potentials (EPs). EPs were recorded at electrodes Fz, Cz, and Pz, in a dichotic signal detection task (oddball paradigm), during attention and inattention conditions. Group differences on attentional EPs replicated published results with flatter and smaller positive waves in +FTD patients and larger late negative waves (FzN4-N7) in -FTD patients. Controlling for dosage, the following were the best groups discriminators. +FTD schizophrenics presented more severe dyskinesia in the orofacial area and poorer verbal scores on L-N. Severe TD correlated with smaller N1 amplitudes. +FTDs also presented distinct attentional EP deficits with abnormally small P3a, a correlate of deficient categorization and orienting. Neuroleptic dosage was not directly correlated to any single motor or cognitive measure, nor to TD indices. The hypothesis of a differential association of TD with distinct attentional/cognitive disorders was generally supported.

Acoustic Stimulation↗