Biomedical subjects

Paul Linkowski

Publications and source records attributed to Paul Linkowski.

11 recordsLinked to original sources

PubMed2006

Major depression in males: effects of age, severity and adaptation on sleep variables.

Sleep abnormalities have been repeatedly demonstrated in major depression. However, the respective influences of age, severity, adaptation and gender have never been clearly disentangled. In a retrospective study, full polysomnograms of 67 male depressive patients and 67 carefully age-matched male healthy control subjects were analyzed. The usual differences associated with the sleep of depressed patients were observed. However, in contrast to most reports, REMS was also found to be reduced; although no comparisons between sexes can be made in this all-male study, one interpretation of this finding is that reduction of REMS is a marker of male depression. Age was found to influence most sleep variables, but not the order of their association with depression. Depression severity was found to be associated with Wake After Sleep Onset (WASO), REMS, and Non-REMS (NREMS). No residual adaptation effect was observed. One of the main markers of depression was in fact the absence of sleep, whether observed as long delays prior to entering sleep, or excessive intermittent awakenings. This sleep reduction affected both REMS and NREMS, in comparable percentages. This supports the hypothesis of a hyperarousal possibly linked to stress.

Adaptation, Psychological↗

PubMed2005

Decoding emotional facial expressions in depressed and anorexic patients.

BACKGROUND: Several studies suggest the existence of impairments in the decoding of emotional facial expressions in various psychopathological conditions. This study investigates the recognition of emotional facial expressions (EFE) in young depressed patients and compares it to patients with eating disorders and control subjects. METHODS: 21 hospitalized female adolescents with major depression, 36 hospitalized female adolescents with eating disorders and 32 female control subjects were investigated with a set of emotional facial stimuli [Hess, U., Blairy, S., 1995. Set of Emotional Facial Stimuli, Department of Psychology, University of Quebec at Montréal, Montréal, Canada]. RESULTS: No significant differences were found between anorexic patients and controls in EFE decoding. Significant results were observed for depressed patients: they were less accurate in EFE decoding compared to anorexic patients and controls for the emotion of anger. LIMITATIONS: Previous studies on EFE decoding in depression and eating disorders used different facial stimuli or methodology. Furthermore, our study concerns only female subjects. These limitations could explain some discrepant result. CONCLUSIONS: The present results support the existence of impairments in the decoding of facial expressions in young female patients suffering from major depression.

Adolescent↗

PubMed2005

Inverse association between Slow Wave Activity per cycle and the number of ultradian sleep cycles per night in healthy humans.

OBJECTIVE: Comparisons of sleep Slow Wave Activity (SWA) during successive sleep cycles rely on the assumption that SWA in a given cycle is independent of the number of ultradian cycles present in a night. This assumption was evaluated here. METHODS: Twenty-six healthy controls with no medical, sleep or psychiatric disorders were selected among 84 candidates and their sleep was recorded at home across 2 consecutive nights after two habituation nights. RESULTS: In comparison with nights with less cycles, nights with more cycles showed significantly more REMS but not more NREMS. No correlation was found between the number of cycles and the integrated SWA per night (epochs visually scored as NREMS). However, inverse correlations were found between the number of cycles and the SWA per cycle. This was significant on both nights in Cycle 1 and strong trends were found for the two subsequent cycles on Night 2. Comparable results were found after removal of nights containing suspected Skipped First REMS episodes. CONCLUSIONS: The SWA in a cycle was found to be inversely correlated to the number of cycles in the first 3 cycles in at least one of the two analyzed nights. SIGNIFICANCE: Differences in the number of cycles per night are a potential bias in the comparisons of SWA per cycles.

Activity Cycles↗

PubMed2005

Sleep disturbance in anxiety disorders.

Many patients suffering from the majority of anxiety disorders complain about their sleep by reporting difficulties in initiating and maintaining it. Polysomnographic studies have shown that, in comparison to normal subjects, the sleep of patients with panic disorder is characterized by longer sleep latency, increased time awake and reduced sleep efficiency. Sleep architecture is normal and there are no significant changes in REM sleep measures. Nocturnal panic attacks are non-REM-related events and occur without an obvious trigger in 18-45% of panic disorder patients. Regarding generalized anxiety disorder, the patients complain of 'trouble sleeping' in 60-70%, while polysomnography has shown increased sleep latency and decreased sleep continuity measures. The findings in REM sleep and sleep architecture generally do not show any aberration to exist. In patients with obsessive-compulsive disorder (OCD) and post-traumatic stress disorder (PTSD), results from the sleep laboratory do not seem to support the subjective complaints of poor sleep. The early reports of shortened REM latency in OCD could not be replicated by recent studies. A dysregulation of the REM sleep control system has been reported for patients with PTSD. Finally, no significant differences were found in all sleep parameters between social phobia patients and controls.

Anxiety Disorders↗

PubMed2004

Is the biological nature of depressive symptoms in borderline patients without concomitant Axis I pathology idiosyncratic? Sleep EEG comparison with recurrent brief, major depression and control subjects.

The relationship between borderline personality disorder (BPD) and the affective disorders is controversial, and we have previously compared BPD and major depression (MD) with endocrinological measures and sleep electroencephalography (S-EEG). We have also compared BPD, MD and recurrent brief depression (RBD) using endocrine tests. We have proposed that depressive symptoms in BPD might have a biological substrate that is distinct from those in depressive illness without comorbid BPD. BPD has been proposed to overlap with RBD, which has been found to share perturbed biological substrates with MD, but we have not found the same biological pattern in BPD. When endocrinological data in BPD, MD and RBD were compared, we did not find evidence of biological linkage between BPD and RBD. To clarify the biological nature of depressive symptoms in BPD, we examined S-EEG characteristics in BPD, RBD, MD and controls. Among 20 BPD patients, 12 were also diagnosed as having clinical RBD. BPD patients showed differences in sleep continuity and especially in sleep architecture compared with RBD, MD and controls. BPD with or without clinical RBD did not show significant differences in any parameter. BPD with or without clinical RBD had less slow sleep activity not only than MD but also than non-borderline RBD patients. We propose that although BPD patients can have concomitant MD, they often exhibit a specific BPD-associated affective syndrome that is different from both MD and non-borderline RBD in the quality and duration of symptoms and the biological substrate.

Adult↗

PubMed2004

Interdependency between heart rate variability and sleep EEG: linear/non-linear?

OBJECTIVE: To investigate whether the interdependency between heart rate variability (HRV) and sleep electroencephalogram (EEG) power spectra is linear or non-linear. METHODS: Heart rate and sleep EEG signals were recorded in 8 healthy young men. Spectral analysis was applied to electrocardiogram and EEG sleep recordings. Synchronization likelihood was computed over the first 3 non-rapid eye movement-rapid eye movement sleep cycles between normalized high frequency of RR intervals (RRI) and all electroencephalographic frequency bands. Comparison to surrogate data of different types was used to attest statistical significance of the coupling between RRI and EEG power bands and its linear or non-linear character. RESULTS: Synchronization likelihood values were statistically greater than univariate surrogate synchronization for all sleep bands both at the individual and the group levels. With reference to multivariate surrogates, synchronization values were statistically greater at the group level and, in a majority of cases, for individual comparison except for sigma and beta bands. CONCLUSIONS: While all electroencephalographic power bands are linked to normalized high frequency RRI band, this interdependency is non-linear for delta, theta and alpha bands. SIGNIFICANCE: Non-linear description is required to capture the full interdependent dynamics of HRV and sleep EEG power bands.

Adolescent↗

PubMed2004

Constant vs auto-continuous positive airway pressure in patients with sleep apnea hypopnea syndrome and a high variability in pressure requirement.

STUDY OBJECTIVES: Auto-continuous positive airway pressure (CPAP) has been reported to have no more efficacy than constant CPAP in unselected patients with sleep apnea hypopnea syndrome (SAHS). The aim of this study was to evaluate patients judged to be good candidates for auto-CPAP because of a high within-night variability in pressure requirement. DESIGN: Single-blind, randomized, cross-over study (2 x 8 weeks) to compare auto-CPAP with constant CPAP. PATIENTS: Outpatients with moderate-to-severe SAHS attending the chest clinic. INTERVENTIONS: Patients were equipped at home in the auto-CPAP mode (model GK418A; Malinckrodt; Nancy, France), using a 4- to 14-cm H(2)O pressure range. Those individuals having a high within-night variability in pressure requirement, assessed at the end of a 14-day run-in period, were included in the cross-over study. Auto-CPAP was compared with constant CPAP (according to a titration night in the sleep laboratory) in terms of compliance, efficacy on apneas (assessed from the pressure monitor), and sleepiness (assessed on the Epworth sleepiness scale). MEASUREMENTS AND RESULTS: Of 90 consecutive patients with SAHS, 27 patients were selected for a within-night variability in pressure requirement exceeding a given threshold. After completion of the cross-over, 24 patients were evaluable. The median percentage of nights the machine was used was 95.5% (range, 45 to 100%) on constant CPAP, and 96.5% (range, 40 to 100%) on auto-CPAP; the median apnea index recorded by the device was 0.40/h (range, 0 to 2.40/h) on constant CPAP, and 0.45/h (range, 0 to 5.80/h) on auto-CPAP (differences not significant). The mean Epworth sleepiness score was significantly (p < 0.01) lower on auto-CPAP (5.1; SD, 2.8) than on constant CPAP (6.1; SD, 2.8). CONCLUSIONS: In patients selected for a high within-night variability in pressure requirement, auto-CPAP administered via a GK418A device was equivalent to constant CPAP based on a titration night in the sleep laboratory. Subjective ratings for sleepiness were slightly lower on auto-CPAP.

Continuous Positive Airway Pressure↗

PubMed2003

First-night effect in the chronic fatigue syndrome.

Since the magnitude of the first-night effect has been shown to be a function of medical conditions and of settings in which polysomnographies are performed, it is essential to evaluate the habituation phenomenon in each case in order to determine the optimal recording methodology. A first-night effect was evidenced in certain cases of chronic fatigue syndrome, but not in others. To clarify this issue, a large group of patients with chronic fatigue syndrome who had no primary sleep disorders were selected and recorded for two consecutive nights in a hospital sleep unit. Several parameters, frequently associated with the first-night effect, were found to be influenced by the recording methodology: Total Sleep Time, Sleep Efficiency, Sleep Efficiency minus Sleep Onset, Sleep Onset Latency, Wake Time, Slow Wave Sleep, Rapid Eye Movement Sleep, Rapid Eye Movement Sleep Latency and Number of Sleep Cycles. Bland and Altman plots determined that the difference scores between the nights included a systematic bias linked to the order of recordings (first-night effect). Factorial analysis grouped the difference scores into three factors. No significant difference was observed between patients with generalized anxiety comorbidity and those with no psychiatric comorbidity, or between those with and without psychiatric comorbidity. Chronic fatigue syndrome must thus be added on the list of conditions where a clinically significant habituation effect takes place.

Adult↗

PubMed2003

Neuroendocrine profiles in mood disorders.

The study of neuroendocrine abnormalities in major mental illness, such as the unipolar and bipolar affective syndromes, has been the focus of interest in the past few years. The neuroendocrine window into the brain has been considered as a fruitful and promising approach to the study of mental disorders, as suggested by studies of some neuroendocrine challenge tests in depression that demonstrated their potential use as biological markers. The modern approach to hormonal dynamics focuses on the circadian and pulsatile profiles that truly represent physiological modulation and tests the hypothesis that an abnormality in circadian rhythms is present in affective illness. From the fundamental point of view, such studies performed using a frequent sampling interval over the 24-h cycle aim to clarify the control and significance of the temporal sleep and wake fluctuations of neuroendocrine system activities. Twenty-four-hour hypersecretion of cortisol, diurnal hypersecretion of growth hormone, and normal 24-h levels of prolactin have been reported in careful chronobiological studies of depressed patients, along with sleep recordings. In addition, a nocturnal quiescent period, and a subsequent increase towards the morning maximum, have been consistently found in a subset of depressed patients suffering from endogenous depression. After successful treatment with antidepressants, most of these abnormalities (with the exception of those found in the prolactin study) tend to correct. The normalization of the timing of hormonal secretion was accompanied by a correction of sleep abnormalities and in particular, a lengthening of the REM latencies. Normalization of cortisol secretion was associated with a decrease in the magnitude of episodic cortisol pulses whereas normalization of growth hormone secretion was due to a diminished number of secretory pulses. In conclusion, a disorder of circadian time-keeping seems to characterize acute episodes of major endogenous depression in some patients. This abnormality as well as the associated increases in adrenocorticotropic and somatotropic activities seem to be a state-, rather than trait-dependent phenomenon.

Animals↗

PubMed2003

Molecular genetics in the analysis of suicide.

Each year, one million people die of suicide. Among the different identified risk factors, genetic factors seem to be part of a multidimensional behavior, including psychiatric, psychosocial, biological factors and physical illness. Family studies have provided evidence for familial transmission in suicide, confirmed in twin and adoption studies. At a molecular level, serotonin seems to be one of the key neurotransmitters implicated in suicidal behavior. Therefore, genes coding for proteins involved in serotonergic neurotransmission have been extensively studied in case-control association studies on suicide. Major findings concern Tryptophan hydroxylase (TPH) gene, particularly in violent suicidal behavior. Though they may seem contradictory, studies on Serotonin transporter (5-HTT), Monaomine oxidase (MAOA), Serotonin 2A and 2C receptors (5-HT2A and 5-HT2C) and Tyrosine hydroxylase (TH) genes are promising. In spite of those observations having some limitations, it appears that genetic factors are a serious risk factor, besides environmental aspects of suicidal behavior.

Aged↗

PubMed2002

Venlafaxine compared with fluoxetine in outpatients with depression and concomitant anxiety.

The aim of this double-blind study was to compare the efficacy and safety of venlafaxine vs. fluoxetine in the treatment of patients with depression and anxiety. A total of 146 moderately depressed patients with associated anxiety were randomized to receive 75 mg/d venlafaxine or 20 mg/d fluoxetine for 12 wk. Dose increases were permitted after 2 wk of treatment, to 150 mg/d venlafaxine and 40 mg/d fluoxetine, to optimize response. At the final visit, a statistically significantly greater efficacy of venlafaxine over fluoxetine was observed on depressive symptoms and concomitant anxiety, and 75.0 and 50.7% of patients administered venlafaxine and fluoxetine, respectively, showed an overall response. A sustained response (for at least 2 wk), present at the end of the study was achieved in 57.8 and 43.3% of patients in the venlafaxine and fluoxetine groups, respectively, and at the final visit, 59.4 and 40.3% of patients, respectively, were in remission (virtually asymptomatic). Dose increases were required by a greater percentage of patients in the fluoxetine group (52.9%), than in the venlafaxine group (37.1%), and in those patients whose dose was increased, a higher efficacy was again observed with venlafaxine. Venlafaxine and fluoxetine were well tolerated, with the most frequently experienced adverse events being nausea and headache. Fewer patients in the venlafaxine group than in the fluoxetine group reported at least one adverse event (55.7 and 67.1% patients, respectively). Venlafaxine therefore proved to be significantly more effective than fluoxetine in improving depressive symptoms and concomitant anxiety.

Adolescent↗