EEG source identification: frequency analysis during sleep

This article deals with a new approach in sleep characterization that combines EEG source localisation methods with standard frequency analysis of multielectrode EEGs. First, we describe the theoretical methodology and the benefits that we get from a three-dimensional image (LORETA) of the cerebral activity related to a frequency band. Then, this new application is used as signal-processing technique on sleep EEG recordings obtained from young male adults using four frequency bands (delta 0.5-3.5 Hz, theta 4.0-7.5 Hz, alpha 8.0-12.5 Hz and beta 13.0-32.0 Hz) in different sleep stages. Finally, we show that the obtained results are highly consistent with other physiological assessments (standard EEG mapping, functional magnetic resonance imaging, etc.), but give us more realistic additional information on the generators of electromagnetic cerebral activity.

Positive association of dopamine D2 receptor polymorphism with bipolar affective disorder in a European Multicenter Association Study of affective disorders

Convincing evidence for a genetic component in the etiology of affective disorders (AD), including bipolar affective disorder (BPAD) and unipolar affective disorder (UPAD), is supported by traditional and molecular genetic studies. Most arguments lead to the complex inheritance hypothesis, suggesting that the mode of inheritance is probably not Mendelian but most likely oligogenic (or polygenic) and that the contribution of genes could be moderate or weak. The purpose of the present European multicenter study (13 centers) was to test the potential role in BPAD and UPAD of two candidate dopaminergic markers, DRD2 and DRD3, using a case-control association design. The following samples were analyzed for DRD2: 358 BPAD/358 control (C) and 133 UPAD/ 133 C subjects, and for DRD3: 325 BPAD/ 325 C and 136 UPAD/136 C subjects. Patients and controls were individually matched for sex, age ( plus minus five years) and geographical origin. Evidence for significant association between BPAD and DRD2 emerged, with an over-representation of genotype 5-5 (P=0.004) and allele 5 (P=0.002) in BPAD cases compared to controls. No association was found for DRD2 in UPAD, and for DRD3 neither in BPAD or UPAD. Our results suggest that the DRD2 microsatellite may be in linkage disequilibrium with a nearby genetic variant involved in the susceptibility to BPAD. Our large European sample allowed for replicating of some previous reported positive findings obtained in other study populations.

Shorter REM latency associated with more sleep cycles of a shorter duration in healthy humans

A significant association between rapid eye movement (REM) sleep latency and the number of non-REM/REM sleep cycles was found 15 years ago in a large retrospective study. The present prospective study further explored this intra-sleep relationship and analyzed the links between these two variables and the mean cycle duration. It was based on a carefully selected group of healthy control subjects whose sleep was polysomnographically recorded at home for 4 sequential nights. The latency of REM sleep was inversely correlated with the number of cycles and positively correlated with the mean cycle duration, both in individual nights and on means of 4 nights. The present study demonstrated that variations in the number of cycles or the mean cycle duration between the nights are far less important than the substantial differences observed between subjects. Present outcomes support the study of sleep cycle periods and frequencies in those psychiatric disorders where REM sleep latencies have been found to be shorter, and they suggest that these variables be included in sleep studies in which cycles are compared with each other.

[Mania, parkinson disease and risperidone. Case report]

Risperidone is an atypical antipsychotic with a low prevalence of extrapyramidal side-effects. The use of this antipsychotic in Parkinson's disease is still controversial. We describe a 59 year-old bipolar patient with Parkinson's disease non-responding to conventional antimanic drugs successfully treated with risperidone.

Effects of the selective activation of 5-HT3 receptors on sleep: a polysomnographic study in healthy volunteers

The respective role of various classes of central serotonin (5-HT) receptors in the regulation of sleep-wakefulness cycles has been the subject of many studies. Notably, it has been reported that 5-HT1A/B receptors are involved in the regulation of rapid eye movement sleep (REMS) and that 5-HT2A/C receptors participate in the control of slow wave sleep (SWS), but the role of 5-HT3 receptors is less well characterised. In this study we investigated the effects of SR 57227A, a potent and selective 5-HT3 agonist, on the sleep EEG of normal young male volunteers. SR 57227A (2.5, 5, 10, 20, 40 mg o.d. and 20 mg b.i.d.) or placebo were administered during 7 consecutive days in seven groups of ten subjects using a parallel group design. Sleep EEG recordings were performed on days 6 and 7 after an habituation session. SR 57227A produced a dose-dependent shift of REMS toward the end of the night without changing REMS and SWS duration nor altering sleep continuity. It suggests a role for the 5-HT3 receptor in the human sleep-wakefulness cycle and particularly in REMS regulation.

The first-night effect may last more than one night

The first-night effect in sleep polysomnographic studies is usually considered to last for one night. However, a few observations have indicated that variables associated to rapid eye movement sleep take longer to stabilize. Notwithstanding, current opinion holds that second nights of recording can be used without restriction for research and clinical purposes. The goal of this study was to describe the dynamics of habituation to polysomnography in optimal conditions. Twenty-six young, carefully screened, healthy subjects were recorded in their home for four consecutive full polysomnographies. Repeated measures ANOVA were applied. Between the two first nights, while there were no differences in sleep duration in non-rapid eye movement sleep, marked modifications in corresponding spectral power were observed. The dynamics of adaptation of rapid eye movement sleep appeared to be a process extending up to the fourth night. Similar dynamics in NREMS and REMS homeostasis have been observed in sleep deprivation studies, and it appears that the same mechanisms may be responsible for the FNE. The longer habituation process of REMS in particular has important implications for sleep research in psychiatry.

Morning and evening TSH response to TRH and sleep EEG disturbances in major depressive disorder

1. The aim of this study was to investigate hypothalamo-pituitary-thyroid axis (HPTA) functioning and sleep EEG disturbances in major depressive disorder. 2. Thyroid function was evaluated by determination of TSH levels before and after 8 AM and 11 PM TRH administration on the same day in a sample of 113 consecutively-admitted DSM-IV major depressed inpatients (72 females aged 44.3 +/- 13.0 and 41 males aged 45.7 +/- 10.7) that underwent sleep EEG recordings. 3. A blunted TSH response occurred in 15.9% for 8 AM deltaTSH (maximum increment above baseline at the 8 AM TRH challenge), in 39.8% for 11 PM deltaTSH and in 77% for deltadeltaTSH (difference between 11 PM deltaTSH and 8 AM deltaTSH). A negative correlation between deltadeltaTSH and duration of awakenings after sleep onset, and a shorter sleep onset latency in patients with a blunted 11 PM deltaTSH were found, but these two significant relationships disappeared after controlling for the effects of gender and age. 4. The present findings do not support the hypothesis that, in major depression, HPTA dysfunctioning, as reflected in TSH response to TRH, may be related to sleep EEG disturbances.

Social adjustment and the course of affective illness: a one-year controlled longitudinal study involving bipolar and unipolar outpatients

The association between social adjustment and recurrent affective episodes was examined in 27 recovered bipolar patients and 24 recovered unipolar patients who had been receiving maintenance treatment for at least 1 year. Social adjustment variables and psychiatric status were assessed by bimonthly interviews over the 1-year period using the Social Adjustment Scale (SAS) and the Research Diagnostic Criteria (RDC). Variations in the social adjustment scores were analyzed in the 2 months preceding the onset of a recurrent affective episode. Furthermore, social adjustment variables at entry into the study were assessed to investigate whether there was any association between these and the potential timing of a recurrent episode. Results revealed no significant deterioration in social adjustment during the 2 months preceding a recurrent affective episode. However, it was demonstrated that there was a relationship between a patient's overall social adjustment score at entry into the study and the onset of recurrent affective episodes, independent of any residual depressive symptomatology. Specifically, impaired work adjustment in bipolar and unipolar patients was associated with recurrent episodes. Impaired social and leisure activities adjustment in bipolar patients was also associated with recurrent episodes, and impaired marital adjustment in unipolar patients was associated with recurrent episodes. These results suggest that social maladjustment could be a risk factor for both unipolar and bipolar recurrent affective episodes and that impairment in specific areas of social functioning could be used to predict outcome.

Mild to moderate sleep respiratory events: one negative night may not be enough

STUDY OBJECTIVES

Reports on the reproducibility of apnea-hypopnea indexes (AHIs) across sequential polysomnography (PSG) sessions are conflicting, leading to a lack of clear recommendations on the optimal use of this technique: is one night of monitoring sufficient or is a second night required in order to safely reject the diagnosis?

DESIGN

Retrospective comparison of two consecutive nights.

SETTING

Sleep unit of a tertiary-care facility.

PATIENTS

Two hundred forty-three subjects with suspected sleep apneas.

INTERVENTIONS

Two sequential PSG sessions in a sleep unit.

MEASUREMENTS AND RESULTS

Using analysis of covariance for repeated measures, with age and body mass index as covariates and gender as a cofactor, a classic first-night effect was found for sleep variables. In addition, a night effect was demonstrated for sleep respiratory variables. Moreover, the high variability of AHIs showed that many patients had their condition diagnosed on only one of the two nights, and more often on the second night than on the first. The gain in detection by adding a second night when the results of testing on the first were negative was between 15% and 25%, according to the AHI obtained on night 1.

CONCLUSIONS

Considering the disability associated with sleep apnea/hypopnea syndrome, as well as its global cost for society, the present study shows that it is worth performing two consecutive PSG sessions or at least a second one when the result of the first one is negative in all patients admitted for apnea detection.

5-HT2a receptor polymorphism gene in bipolar disorder and harm avoidance personality trait

The purpose [corrected] of this study was to investigate the relationship between bipolar disorder and the harm avoidance personality trait (HA), and the genetic contribution of the polymorphic DNA variation T102C in exon 1 of 5-HTR2a (chromosome 13q14-21) in bipolar disorder and HA personality trait. Forty bipolar patients and 89 normal subjects completed the TPQ questionnaire and were genotyped for 5-HT2a. Bipolar patients scored higher than normal subjects on the HA dimension. However, no contribution of the 5-HTR2a polymorphism on the bipolar disorder or on the HA personality trait emerged. Despite the limited sample size, these results exclude a major effect of the 5-HTR2a polymorphism on bipolar disorder and HA personality trait but not a minor effect.

Prolactin response to D-fenfluramine and suicidal behavior in depressed patients

Previous studies of the prolactin response to D-fenfluramine in depressed patients have yielded inconsistent results. This may be because they did not address the question of suicidality. We carried out this study to test the hypothesis that lower prolactin response to D-fenfluramine is more closely associated with suicidal behavior than with depression itself. A D-fenfluramine test was performed in a sample of 18 healthy control subjects and in 85 drug-free inpatients with a DSM-III-R diagnosis of major depressive episode (49 with a history of suicide attempt, 36 without). Depressed inpatients with a history of suicide attempt showed a significantly lower prolactin response to D-fenfluramine compared to depressed inpatients without such a history and compared to control subjects. Healthy control subjects and depressed inpatients without a history of suicide attempt showed comparable levels of prolactin after D-fenfluramine. Time elapsed since suicide attempt did not influence prolactin level (baseline or post-stimulation). Results show that in our depressed drug-free inpatient sample, prolactin response to D-fenfluramine seems to be a marker of suicidality, but not of depression itself. We suggest that it is a trait marker of suicidality.

A European multicenter association study of HTR2A receptor polymorphism in bipolar affective disorder

The available data on the role of 5-HT in a variety of behaviors support the hypothesis that a dysfunction in brain serotoninergic system activity contributes to vulnerability to major depression. The diversity in the electrophysiological actions of 5-HT in the central nervous system can now be categorized according to receptor subtypes and their respective effector mechanisms. In particular, the implication of central postsynaptic 5-HT2A receptor in affective disorders has been supported by findings consistent with the hypothesis of 5-HT2A receptor up-regulation in depression. For these reasons, the 5-HT2A receptor (HTR2A) gene can be considered as a candidate gene in bipolar affective disorder (BPAD). We tested the possible genetic contribution of the polymorphic DNA variation T102C in exon 1 of HTR2A (chromosome 13q14-21) gene in a large European multicentric case-control sample. Allele and genotype frequencies, as well as homo-heterozygote distributions were compared between the two groups of 309 bipolar affective disorder patients and 309 matched controls. No significant differences were observed in the allelic and genotypic (also for homo-heterozygote) distribution between BPAD and controls. These results indicate that, in our sample, the 5-HT2A receptor polymorphism studied is unlikely to play a major role in the genetic susceptibility to BPAD. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:136-140, 2000.

Changes in EEG power density during sleep laboratory adaptation in depressed inpatients

BACKGROUND

The aim of the present study was to evaluate the first-night effect in depressed inpatients, using standard sleep measures as well as all-night spectral analysis of the sleep electroencephalogram (EEG).

METHODS

Eighteen drug-free, depressed inpatients were studied for 3 consecutive nights in the hospital sleep laboratory.

RESULTS

Visual sleep scoring results showed a slight but measurable first-night effect, characterized by a reduction of rapid eye movement (REM) sleep amount and increased wakefulness. Sleep EEG spectral analysis showed significantly reduced delta (p <.01) and theta (p <.05) power density in non-REM (NREM) sleep of the first night compared with that of the second and third nights. These differences were limited to the early part of the sleep period, a time during the night that is particularly vulnerable to the effects of depressive disorder. In contrast to the NREM sleep findings, spectral REM variables studied did not significantly vary across the three nights.

CONCLUSIONS

The results obtained suggest that first-night data should not be simply discarded but could be used in subsequent analyses and could be considered useful in the evaluation of the sleep of depressed patients.

Shortened REM latency as a psychobiological marker for psychotic depression? An age-, gender-, and polarity-controlled study

BACKGROUND

Previous reports suggest that the clinical dichotomy separating psychotic and nonpsychotic depression corresponds to different neurobiological profiles. The aim of the present study is to further investigate the psychobiological correlates of these two particular depressive subtypes.

METHODS

Thyroid-stimulating hormone response to thyrotropin-releasing hormone postdexamethasone cortisol levels, and electroencephalgraphic sleep characteristics of 44 psychotic major depressive patients were compared to those of 44 nonpsychotic depressives matched for age, gender, and polarity.

RESULTS

Some biological disturbances usually associated with depression (increased wakefulness, diminished rapid eye movement latency, hypercortisolism, blunted thyroid-stimulating hormone response to thyrotropin-releasing hormone stimulation) seemed to be significantly more pronounced in the psychotic depressed group as a reflection of greater illness severity; however, shortened REM latency was not influenced by severity and seemed to be more specifically related to the co-occurrence of psychotic and depressive symptoms.

CONCLUSIONS

Our data provide further support for the validity of the clinical dichotomy separating psychotic and nonpsychotic major depression independently of severity.

[Multicenter trials in the treatment of depression: some methodological issues]

In recent year, multicenter psychopharmacological trials have met an increasing interest since through them it has become easier, in a relatively short time, to collect large samples of patients. Methodological problems common to all psychopharmacological trials may be sharpened in this kind of investigation. Others, that are specifically related to multicenter studies, may also arise. Methodological difficulties addressed in this paper are those related to patients selection procedure, to strategies for data analysis and to issues about design or management of the study. Strictly speaking, the results of a such a trial could only be generalised to patients exhibiting the characteristics of the studied sample. Moreover, before pooling the data obtained at each center, preliminary analyses should demonstrate that centers do not differentiate themselves on the basis of patient characteristics. The new drug has to be compared to both a placebo and a reference compound. In this way, and through the replication of the expected difference between the placebo and the reference drug, the methodological validity of the trial could be ascertained. The treatment with a placebo is warranted by the facts that illness natural course and non specific treatment effects have to be taken into account. Satisfactory levels of inter-rater reliability have to be achieved and maintained through training sessions with the participation of all the centers involved in the trial. Statistical analyses generally focus on the intent to treat sample. However, due to the delayed activity of antidepressant drugs, efficacy analyses could be limited to patients treated at least 14 days. Multivariate analysis of variance is particularly well suited for data analysis but can be invalidated by an excess of dropouts. To overcome this problem, other techniques such as survival analysis and random regression models have been proposed. This latter procedure seems to be particularly promising for analysing data of multicenter trials since it can assess treatment difference while adjusting for inter-center variability.

[Heredity and role of serotonin in aggressive impulsive behavior]

The idea that heredity could influence behaviour, including personality is very old. Until the early 1980s, the evidence for genetic influences on personality derived almost exclusively from twin studies. More recently, studies comparing twins raised together with those raised in different environment confirmed that about 40% of the observed personality variance can be attributable to genetic factors. Since complex behaviours, such as those underlying personality functioning, are likely to be influenced by many genes, a continuum of genetic risk underlying behavioural dimensions that extend from normal to abnormal behaviour has been hypothesized. Behaviours related to aggressive impulses regulation could delineate a biologically anchored model of dispositions to both normal and pathological functioning: these behaviours are identified in animal species where they are genetically transmitted, and a growing body of evidence suggests that disturbances in the regulation of aggressive impulses could belong to a behavioural dimension (disturbances of impulse control) linked to serotonin. Theorists involved in modelling personality according to psychobiologic basis agree with the idea of an inhibitory function of serotonin on impulsive behaviour and recognise that the way individuals control their impulses could underlie a basic psychobiological personality dimension. According to genotypes and to environmental factors, these serotonin mediated behaviours may be diversely expressed varying from minor personality peculiarities (characterised by impulsivity, hostility, irritability, psychopathic deviance, excessive violence or by more clear-cut personality dysfunctioning such as antisocial, borderline, narcissistic and histrionic personality traits or disorders) to major psychiatric disturbances (suicidal behaviour, overt aggressive behaviour, intermittent explosive disorder, pathological gambling, pyromania, bulimia and some type of substance or alcohol abuse). Finally, recent molecular genetic studies have demonstrated that genes encoding some key proteins involved in serotonin transmission could present some polymorphism in relation with impulsive-aggressive behaviours.

Does sleep EEG data distinguish between UP, BPI or BPII major depressions? An age and gender controlled study

Clinical characteristics and sleep EEG data of 14 unipolar (UPR), 14 bipolar I (BPI) and 14 bipolar II (BPII) patients, matched for age and gender, were investigated during a major depressive episode. We observed a remarkable similarity in the clinical characteristics of the three samples and, concerning sleep EEG data, a trend to a higher percentage of awakening among BPI patients. Pairwise comparisons of the three subgroups showed that only the Newcastle rating scale score reached significant difference between BPI and UPR groups. We observed trends regarding the difference of awakening both between BPI and BPII groups and between BPI and UPR groups, difference of percentage of REM sleep between BPI and BPII groups and difference of Sleep Period Time between BPII and UPR groups. We also observed that the distribution of REM latencies in the BPI subgroup was different from the two others.

Neuroendocrine and clinical characteristics of major depressed patients exhibiting sleep-onset REM

BACKGROUND

Previous reports suggest an association between sleep-onset REM (SOREM) and some clinical characteristics in depressive illness such as age, psychosis, and depression severity. The present study is aimed at further investigating clinical and neuroendocrine correlates of SOREM, controlling for the age-related variability in clinical data.

METHODS

Thyroid-stimulating hormone response to thyrotropin-releasing hormone, postdexamethasone cortisol levels, and clinical characteristics of 25 major depressive (MD) patients exhibiting SOREM in at least one of three consecutive recording nights were compared to those of 25 age- and sex-matched MD patients with three REM latencies above 50 min.

RESULTS

SOREM patients experienced more affective episodes leading to hospitalization and a shorter duration of current episode than patients with three REM latencies above 50 min. No association between psychosis and SOREM could be demonstrated, and hypothalamic-pituitary-adrenal or -thyroid axis disturbances were not more prevalent in SOREM patients.

CONCLUSIONS

Our results suggest that clinical history rather than cross-sectional clinical characteristics relates to the occurrence of SOREM in major depressed patients.

Association between novelty-seeking and the dopamine D3 receptor gene in bipolar patients: a preliminary report

Recent studies in healthy controls suggest an association between novelty-seeking (NS) and the dopamine D4 receptor (DRD4) gene. In this study, we further investigated the relationship between genes implicated in dopamine as well as serotonin neurotransmission and personality traits in bipolar (BP) disorder. Scores on the Tridimensional Personality Questionnaire were examined in 37 recovered Research Diagnostic Criteria-diagnosed BP patients genotyped for DRD3, DRD4, and serotonin 2A receptor (5HTR2a) polymorphisms. Carriers of DRD3 allele 1 showed significantly lower NS values compared to patients without this allele. Scores on NS and on harm-avoidance were not related to DRD4 or 5HTR2a polymorphisms. These preliminary results suggest a role for D3 receptor in NS expression in BP patients.

The dexamethasone suppression test and sleep electroencephalogram in nonbipolar major depressed inpatients: a multivariate analysis

BACKGROUND

The present study further examined relationships between postdexamethasone cortisol plasma values and sleep electroencephalogram (EEG) parameters.

METHODS

The dexamethasone suppression test (DST) and polysomnographic recordings were performed in a sample of 300 inpatients with primary major depressive disorder (MDD) (102 men and 198 women, mean age 44 +/- 12 years, range 20-74 years) consecutively admitted to Erasme Hospital (Brussels, Belgium) between 1981 and 1992.

RESULTS

The DST was abnormal in 40% of the sample. Postdexamethasone cortisol plasma values at 4:00 PM were significantly influenced by age, but not by gender. They were also significantly and positively correlated with weight loss, total scores on the Hamilton Depression Rating Scale, total scores on the Newcastle Scale, percentage of awakenings during sleep, and percent of stage 1. They were significantly and negatively correlated with percent of stage 2, slow-wave sleep, and REM sleep. Multiple regression analyses were conducted in two successive steps. First among clinical variables, only age and depressive symptom severity remained correlated with postdexamethasone plasma cortisol values. In the second step, with age and severity held constant, postdexamethasone plasma cortisol values were positively associated with amount of wake time and stage 1, and negatively with amount of slow-wave sleep.

CONCLUSIONS

These findings provide further indirect support for an overarousal state in MDD with sympathoadrenal system hyperactivity and impaired sleep continuity. They also underline the importance of taking into account various clinical confounding factors in the interpretation of both DST and sleep EEG results.

[Tridimensional Personality Questionnaire (TPQ): validation in a French-speaking control population]

Among the dimensional scales that measure personality, Cloninger's TPQ (Tridimensional Personality Questionnaire) holds a place apart in the literature, because the hypotheses it relies on are partially biological. The questionnaire (100 forced binary items) includes three axes: "Novelty Seeking", "Harm Avoidance" and "Reward Dependence", each theoretically bound to a preferential neuromediator, respectively dopamine, serotonin and norepinephrine. Each axis includes four minor subscales. The study presented here is the analysis of 104 control volunteers from both genders (59 males). This database is the first to be published with a French-speaking population. The comparison with Cloninger's normative database shows many similarities: the mean values for the 3 axes are relatively close. The population studied here is younger and this factor could play a role in the somewhat higher mean novelty seeking scores found here. The three axes show a normal distribution. Skewness and kurtosis are between -1 and +1 for all the subscales, except here for NS2. Factorial structure is quite similar to Cloninger's results. The three first axes correspond to the variables isolated in the first studies and the fourth one includes the same subscales as in the large American database. Inverse correlation between age and novelty seeking, positive correlation between female gender and harm avoidance and reward dependence were also found. However, no correlation was found between novelty seeking and male gender. A correlation was found between level of instruction and NS1 only, not with the whole NS axis. Eighty-seven % of volunteers presented with at least one standard deviation on at least one axis and 68% on at least two. This does not seem to have been described previously. It can be a sign of the difficulty of human beings to show a balanced personality. In conclusion, the database presented here shows many similarities with Cloninger's normative database. This underscores its value for comparisons in clinical trials in the future.

Critical analysis of the theories advanced to explain short REM sleep latencies and other sleep anomalies in several psychiatric conditions

One of the most consistent and most studied sleep modifications in several psychiatric conditions is the shortening of the rapid eye movement (REM) sleep latency. While its clinical usefulness is still to be proven and its meaning relatively obscure, the appearance of a short REM latency continues to be a daily fact in sleep laboratories. Many theories compete to explain what is observed, the most important being the circadian rhythm hypotheses, the homeostatic model and the reciprocal interaction model. These three are summarised and their pros and cons are exposed in a systematic manner. Points of conflict, possible convergences and limitations are discussed in the light of recent developments on the general theories of sleep regulation.