Ultradian rhythms and temporal coherence in sleep EEG in depressed children and adolescents

A systematic review of quantitative EEG as a possible biomarker in child psychiatric disorders

Quantitative EEG (qEEG) has emerged as a potential intermediate biomarker for diagnostic clarification in mental illness. This systematic review examines published studies that used qEEG in youth with psychiatric illness between 1996 and 2017. We conducted a comprehensive database search of CINAHL, PubMed, and Cochrane using the following keywords: "quantitative EEG" and depression (MDD), anxiety, attention-deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), eating disorder, conduct, substance use, schizophrenia, post-traumatic stress disorder, and panic disorder. Our search yielded 516 titles; 33 met final inclusion criteria, producing a total of 2268 youth aged 4-18. qEEG was most frequently studied as a potential diagnostic tool in pediatric mental illness; few studies assessed treatment response. Studies show higher theta/beta ratio in ADHD vs healthy controls (HC). The most consistent finding in ASD was decreased coherence in ASD vs HC. Studies show MDD has lower temporal coherence and interhemispheric coherence in sleep EEGs than HC. Further research is needed in the areas of mood, anxiety, ASD, and relationship to treatment. It remains unknown if abnormalities in qEEG are nonspecific markers of pediatric psychiatric illness or if they have the potential to differentiate types of psychopathology.

Sleep and mental disorders: A meta-analysis of polysomnographic research

Investigating sleep in mental disorders has the potential to reveal both disorder-specific and transdiagnostic psychophysiological mechanisms. This meta-analysis aimed at determining the polysomnographic (PSG) characteristics of several mental disorders. Relevant studies were searched through standard strategies. Controlled PSG studies evaluating sleep in affective, anxiety, eating, pervasive developmental, borderline and antisocial personality disorders, attention-deficit-hyperactivity disorder (ADHD), and schizophrenia were included. PSG variables of sleep continuity, depth, and architecture, as well as rapid-eye movement (REM) sleep were considered. Calculations were performed with the "Comprehensive Meta-Analysis" and "R" software. Using random effects modeling, for each disorder and each variable, a separate meta-analysis was conducted if at least 3 studies were available for calculation of effect sizes as standardized means (Hedges' g). Sources of variability, that is, sex, age, and mental disorders comorbidity, were evaluated in subgroup analyses. Sleep alterations were evidenced in all disorders, with the exception of ADHD and seasonal affective disorders. Sleep continuity problems were observed in most mental disorders. Sleep depth and REM pressure alterations were associated with affective, anxiety, autism and schizophrenia disorders. Comorbidity was associated with enhanced REM sleep pressure and more inhibition of sleep depth. No sleep parameter was exclusively altered in 1 condition; however, no 2 conditions shared the same PSG profile. Sleep continuity disturbances imply a transdiagnostic imbalance in the arousal system likely representing a basic dimension of mental health. Sleep depth and REM variables might play a key role in psychiatric comorbidity processes. Constellations of sleep alterations may define distinct disorders better than alterations in 1 single variable. (PsycINFO Database Record

Sleep in adolescent depression: physiological perspectives

Depression and disturbed sleep are intimately and bidirectionally related. During adolescence, the incidence of both insomnia and major depression increases simultaneously, in a gender-specific manner. The majority of depressed adolescents suffer from different types of subjective sleep complaints. Despite these complaints, the results from polysomnographic studies in depressed adolescents remain inconsistent. In general, similar features to those seen among adults with depressive disorder (e.g. abnormalities in rapid eye movement sleep and difficulties in sleep onset) have been reported, but expressed to a lesser degree. The inconsistency in findings may be linked with maturational factors, factors related to the stage of illness and greater heterogeneity in the clinical spectrum of depression among adolescents. The exact neurobiological mechanisms by which sleep alterations and depression are linked during adolescence are not fully understood. Aberrations in brain maturation, expressed at different levels of organization, for example gene expression, neurotransmitter and hormone metabolism, and activity of neuronal networks have been suggested. The circadian systems may change in adolescent depression beyond that observed during healthy adolescent development (i.e. beyond the typical circadian shift towards eveningness). A number of therapeutic approaches to alleviate sleep disruption associated with depression have been proposed, but research on the efficacy of these interventions in adolescents is lacking. Knowledge of the neurobiological links between sleep and depression during adolescence could lead to new insights into effective prevention and treatment of depression.

Polysomnographic features of early-onset depression: a meta-analysis

BACKGROUND

Undiagnosed major depressive disorder (MDD) is associated with increased morbidity in children and adolescents. This study evaluated features of sleep macro- and microarchitecture assessed by polysomnography (PSG) as diagnostic markers for MDD in children and adolescents.

METHODS

MEDLINE, PSYCINFO, EMBASE and PUBMED were searched from their availability dates to March 1st, 2013. The literature search identified 932 abstracts of which 51 studies were retrieved and 28 were included in the analysis. Study design, features of sleep macro- and microarchitecture, demographic and clinical characteristics of study groups were extracted for each study.

RESULTS

There were modest differences on sleep macroarchitecture between children and adolescents with MDD and healthy controls. The most robust difference was found in sleep latency, 31% of adolescents with MDD had increased sleep latency. Age, suicidal ideation, suicidal behavior, and psychiatric comorbidities were significant predictors of sleep macroarchitecture. Modest differences were found for sleep microarchitecture, intrahemispheric and interhemispheric temporal coherence was decreased in a third of patients with MDD. Age was a significant predictor of sleep microarchitecture.

LIMITATIONS

This meta-analysis is limited by the small number of studies on sleep macroarchitecture in children with MDD and studies on sleep microarchitecture overall and by the heterogeneity in methodology between studies.

CONCLUSIONS

This synthetic review of the existing literature is among the largest to quantitatively assess impaired sleep as a diagnostic marker for MDD in children and adolescents. Knowledge of sleep macro- and microarchitecture in early-onset MDD may aid the clinician in developing a treatment strategy for MDD-related sleep symptoms in a subset of patients.

Sleep complaints among adolescent outpatients with major depressive disorder

OBJECTIVE

The objective of our study was to examine the prevalence rates of different sleep complaints among adolescent outpatients with major depressive disorder (MDD). Further, we examined whether depressed adolescents with and without different sleep disturbances differ in terms of severity of depression, the presence of comorbid psychiatric disorders, and the symptom profile of depression.

METHODS

A total of 166 Finnish adolescent psychiatric outpatients (age 13-19; mean 16.5 years old; 17.5% boys) diagnosed with unipolar MDD (as defined by DSM-IV criteria) were included in the study. Their sleep complaints were assessed with self-rating scales and clinical research interviews.

RESULTS

The prevalence rate of subjective sleep complaints in adolescents with MDD was high: 83% of the adolescents experienced significantly disturbed sleep. The most common types of sleep complaints were nonrestorative sleep (69%) and insomnia (51%). The presence of sleep disturbances was associated with severity of depression: Hamilton Depression Rating Scale (HDRS) and Beck Depression Inventory (BDI) total sum scores were highest in adolescents with multiple sleep disturbances and lowest in adolescents with no sleep problems. Adolescents with multiple sleep disturbances differed most from adolescents with no or minor sleep disturbances in terms of thoughts about death, suicidal thoughts, and anhedonia.

CONCLUSIONS

These findings suggest a close link between sleep disturbances and the severity of depression in adolescent outpatients with MDD. In particular, the link between sleep disturbances and thoughts about death and suicidal thoughts calls for attention to sleep problems among depressed adolescents in clinical settings.

The sleep macroarchitecture of children at risk for depression recruited in sleep centers

Objective

The primary aim of this study was to compare the sleep macroarchitecture of children and adolescents whose mothers have a history of depression with children and adolescents whose mothers do not.

Method

Polysomnography (PSG) and Holter electroencephalogram (EEG) were used to compare the sleep architecture of 35 children whose mothers had at least one previous depressive episode (19 boys, aged 4–18 years, “high-risk” group) and 25 controls (13 males, aged 4–18 years, “low-risk” group) whose mothers had never had a depressive episode. The total sleep time, wakefulness after sleep onset (WASO), sleep latency, sleep efficiency, number of awakenings per hour of sleep, percentages of time spent in each sleep stage, rapid eye movement (REM) latency and the depressive symptoms of participants were measured.

Results

In children (4–12 years old), the high-risk group exhibited significantly more depressive symptoms than controls (P = 0.02). However, PSG parameters were not significantly different between high-risk children and controls. In adolescents (13–18 years old), the high-risk subjects presented with significantly more depressive symptoms (P = 0.003), a significant increase in WASO (P = 0.019) and a significant decrease in sleep efficiency compared to controls (P = 0.009).

Conclusion

This study shows that children and adolescents born from mothers with a history of at least one depressive episode had significantly more depressive symptoms than controls. However, only high-risk adolescents presented with concurrent alterations of sleep macroarchitecture.

Sex Differences in Slow-wave Electroencephalographic Activity (SWA) in Adolescent Depression

Sleep disturbances, present in more than 90% of major depressive disorder (MDD) patients, are moderated by sex in adult MDD. In particular, slow-wave electroencephalographic activity (SWA; 0.5-4 Hz) accumulation is low and dissipation impaired. This SWA abnormality in depressed adult males does not change with age, suggesting that SWA abnormality appears at early ages. The present study evaluated sex differences in SWA in adolescents with MDD compared to healthy controls. We evaluated regularized sleep-wake schedules at home for 5-7 days, followed by two consecutive nights of sleep EEG recording. The study included 104 participants, 52 symptomatic and depressed subjects (MDD: 20 males and 32 females) and 52 healthy controls (HC: 20 males and 32 females), aged 13-18 years. SWA power and dissipation, and duration and latencies to each Non-Rapid Eye Movement (NREM) sleep period were calculated for each group. Results showed that SWA accumulation in the first NREM period was lower and its dissipation across the night more irregular in MDD males compared to HC males (P<0.009). By contrast, SWA was equivalent in MDD and HC females. In conclusion, as reported in adult MDD, the accumulation and dissipation of SWA was abnormal in depressed adolescents, but only in males. SWA abnormalities in adolescent MDD may relate to different depressive symptoms in females and males. These results underscore the need to develop sex-specific therapies to enhance and restore SWA in depressed adolescents.

Reduced sleep spindle activity in early-onset and elevated risk for depression

OBJECTIVE

Sleep disturbances are common in major depressive disorder (MDD), although polysomnographic (PSG) abnormalities are more prevalent in adults than in children and adolescents with MDD. Sleep spindle activity (SPA) is associated with neuroplasticity mechanisms during brain maturation and is more abundant in childhood and adolescence than in adulthood, and as such, may be a more sensitive measure of sleep alteration than PSG in early-onset depression. This study investigated SPA changes related to early-onset MDD, comparing individuals already ill with MDD and individuals at high-risk for MDD with healthy nondepressed controls.

METHOD

The study included 63 participants (8 to 15 years of age): 21 currently depressed individuals, 21 individuals at high risk for MDD based on positive family history of MDD, and 21 healthy control individuals with no personal or family history of psychiatric illness. All participants maintained a regular sleep/wake schedule for 5 days, followed by 2 nights in the laboratory. SPA was analyzed in Stage 2 of non-rapid eye movement sleep.

RESULTS

SPA differed significantly between groups, particularly in the late part of the night (F(2,62) = 7.3, p = .001). Although the difference was greatest between the MDD and healthy control groups, both the MDD (p = .0004) and at high-risk groups (p = .02) had significantly lower SPA compared with healthy controls. SPA deficit was more prominent in females than in males (F(5,62) = 5.19, p = .005).

CONCLUSIONS

Low SPA characterizes youths with MDD and those at high risk for MDD, particularly girls, suggesting that early-onset depression and risk for the MDD are associated with decreased neuroplasticity.

Sleep characteristics of children and adolescents with attention deficit-hyperactivity disorder

This article reviews sleep characteristics of children and adolescents who have attention-deficit/hyperactivity disorder (ADHD). Research on sleep disturbances in individuals who have ADHD without comorbid conditions, measured both objectively and subjectively, is first presented. The impact of primary sleep disorders associated with ADHD is then discussed. The effects of psychiatric comorbidities on the sleep patterns of children and adolescents who have ADHD are then reviewed, and sleep alterations associated with medications used to treat ADHD and comorbid conditions are addressed.

Mood-related sleep problems in children and adolescents

Sleep problems are an essential part of the current diagnostic criteria for depressive and bipolar disorders in children and adolescents. Whereas many studies have reported subjective sleep problems in youth with depression or bipolar disorder, except for reduced rapid eye movement latency associated with depression, few objective mood-related sleep abnormalities have been consistently identified. Recent technologic advances, such as spectral EEG and actigraphy, hold promise for revealing additional objective disturbances. There are presently few evidence-based published practice recommendations for mood-related sleep problems in youth. In this article, the authors chronologically review research on the phenomenology and treatment of sleep difficulties in youth with depressive and bipolar disorders and present research-based and clinically guided recommendations for the assessment and treatment of these problems.

Characteristics, correlates, and outcomes of childhood and adolescent depressive disorders

Depressive illness beginning early in life can have serious developmental and functional consequences. Therefore, understanding the disorder during this developmental stage is critical for determining its etiology and course, as well as for deveiopinq effective intervention straieqies. This paper summarizes current knoviedqe reqardinq the etiology, phenomenoiogy, correlates, natural course, and consequences of unipolar depression in children and adolescents. Using adult depression as a framevork, the unique aspects of childhood and adolescence are considered in order to better understand depression within a developmental context. The data suggest that the clinical presentation, correlates, and natural course of depression are remarkably similar across the lifespan. There are, however, important developmental differences. Specifically, the familial and psychological context in which depression develops in youngsters is associated with variability in the frequency and nature of depressive symptoms and comorbid conditions among children and adolescents. Maturational differences have also been identified in the neurobiological correlates of depression. These developmental differences may be associated with the observed variability in clinical response to treatment and longitudinal course. Characterization of the developmental differences will be helpful in developing more specific and effective interventions for youngsters, thereby allowing them to reach their full potential as adults.

Executive functioning in children and adolescents with Major Depressive Disorder

The present investigation examined neurocognitive functioning, focusing on executive functioning (EF), in 39 children and adolescents with Major Depressive Disorder (MDD) and 24 healthy control subjects all ages 8 to 17 years. The Wechsler Intelligence Scale for Children-Third Edition along with several measures of executive functioning including the Wisconsin Card Sorting Task, Trail Making Test, Controlled Oral Word Association Test, and the Stroop Color Word Test were administered. The neurocognitive profiles for the group of depressed children and adolescents were grossly intact as most scores on intellectual and EF measures fell within the average range and did not differ from the comparison group. Mental processing speed was decreased in the MDD versus normal control group and 27% of the depressed group performed below average on the Trail Making Test. This investigation provided a good base from which to compare future literature on EF in outpatients with early-onset MDD.

Electroencephalographic sleep and hypothalamic-pituitary-adrenal changes from episode to recovery in depressed adolescents

OBJECTIVE

The study examined electroencephalographic (EEG) sleep and hypothalamic-pituitary-adrenal (HPA) changes associated with depressive episode and during recovery in adolescent depression.

METHODS

Sixteen adolescents with major depressive disorder and 16 volunteers with no personal or family history of psychiatric disorder participated in a three-night EEG sleep protocol along with nocturnal urinary free cortisol (NUFC). Depressed subjects also were restudied during stable remission from the depressive episode.

RESULTS

Compared with controls, depressed adolescents had significantly reduced sleep efficiency, shorter latency to rapid eye movement (REM) sleep, increased phasic REM sleep, and elevated NUFC excretion. Among depressed subjects, EEG sleep values did not change significantly from episode to remission. NUFC excretion reduced significantly during remission from the depressive episode.

CONCLUSIONS

The findings that EEG sleep measures are independent of clinical state, whereas HPA variables are state dependent, suggest that sleep and HPA measures make a differential contribution to our understanding of the pathophysiology and prognosis of mood disorders in adolescent patients.

ADHD subtypes and comorbid anxiety, depression, and oppositional-defiant disorder: differences in sleep problems

OBJECTIVE

Sleep problems were analyzed in children with ADHD (Attention-deficit hyperactivity disorder).

METHODS

Scales were completed by parents of 135 control children and 681 children with ADHD combined type (ADHD-C) or inattentive type (ADHD-I) with or without comorbid oppositional defiant disorder (ODD), anxiety, or depression.

RESULTS

Children with ADHD-I alone had the fewest sleep problems and did not differ from controls. Children with ADHD-C had more sleep problems than controls and children with ADHD-I. Comorbid anxiety/depression increased sleep problems, whereas ODD did not. Daytime sleepiness was greatest in ADHD-I and was associated with sleeping more (not less) than normal. Medicated children had greater difficulty falling asleep than unmedicated children.

CONCLUSIONS

Differences in sleep problems were found as a function of ADHD subtype, comorbidity, and medication.

Social neuroscience of child and adolescent depression

The social neuroscience of child and adolescent depression is inherently multidisciplinary. Depressive disorders beginning early in life can have serious developmental and functional consequences. Psychopathology research has described depression's defining clinical and contextual features, and intervention research has characterized its response to treatment and prevention programs. Neuroendocrine, electrophysiological, and neuroimaging studies have identified core neurobiological aspects of early-onset mood disorders. These areas are reviewed using a developmental social neuroscience perspective for integrating disparate observations. The paper introduces a dynamic adaptive systems framework, and it discusses hedonic capacity, stress sensitivity, ruminative self-focus, and attentional impairments as fundamental components of mood disorders.

The effects of total sleep deprivation on brain functional organization: Mutual information analysis of waking human EEG

Sleep deprivation can affect the waking electroencephalogram (EEG) that may reflect functional organization of the brain. We examined the effect of total sleep deprivation (TSD) on functional organization between different cortical areas from the waking EEG. Waking EEG data were recorded from 18 healthy male volunteers with eyes closed after 8-h night's sleep and after 24 h of TSD. The averaged cross mutual information (A-CMI) after 24 h of TSD were compared to before TSD. 24 h of TSD yielded the decreased A-CMIs in the inter-hemispheric C3-F4, C3-F8, and C3-C4 pairs: therefore, the electrodes that contribute to pairs with significant decrease of A-CMI were C3, F4, F8, and C4. The decreased A-CMIs between C3 and right frontal and central brain areas after 24 h of TSD may reflect the changes of cortico-cortical functional organization by homeostatic process during TSD. Our results of the frontal-area-related A-CMI decreases may support that the frontal brain regions are related to the homeostatic deterioration of brain function due to TSD.

Sleep and psychiatry

Psychiatric disorders constitute 15.4% of the disease burden in established market economies. Many psychiatric disorders are associated with sleep disturbances, and the relationship is often bidirectional. This paper reviews the prevalence of various psychiatric disorders, their clinical presentation, and their association with sleep disorders. Among the psychiatric disorders reviewed are affective disorders, psychosis, anxiety disorders (including posttraumatic stress disorder), substance abuse disorders, eating disorders, and attention deficit/hyperactivity disorders. The spectrum of associated sleep disorders includes insomnia, hypersomnia, nocturnal panic, sleep paralysis, hypnagogic hallucinations, restless legs/periodic limb movements of sleep, obstructive sleep apnea, and parasomnias. The effects on sleep of various psychotropic medications utilized to treat the above psychiatric disorders are summarized.

Sleep microarchitecture in childhood and adolescent depression: temporal coherence

Previous work has indicated that low temporal coherence of ultradian sleep EEG rhythms is characteristic of depressed patients and women in particular. It may also be evident in depressed children and adolescents, although most published studies are limited in sample size. The present study evaluated temporal coherence of sleep EEG rhythms in 173 children and adolescents 8-17 years of age, including 97 who met criteria for major depressive disorder (MDD) and were symptomatic but unmedicated at the time of study and 76 healthy controls. Temporal coherence of all-night sleep EEG rhythms was evaluated on the second of two nights in the laboratory. Data were coded for diagnostic group, gender and age and subjected to MANOVAs. Temporal coherence was significantly lower in adolescents with MDD, compared to healthy controls. Findings were most robust for coherence between left and right beta and between delta and beta in both hemispheres. Both gender and age strongly influenced between-group differences, with the lowest temporal coherence among MDD girls, even in those under 13 years of age. In conclusion, early onset depression is associated with a reduction in synchronization of sleep EEG rhythms that shows a differential maturational course in boys and girls.

Subjective sleep complaints in pediatric depression: a controlled study and comparison with EEG measures of sleep and waking

OBJECTIVE

Children with major depressive disorder (MDD) often complain of sleep disturbances; however, polysomnographic studies have failed to find objective evidence of these disturbances. This article examines subjective sleep reports of children with MDD and healthy controls focusing on comparing subjective and objective sleep measures.

METHOD

Fifty-one subjects with MDD and 42 healthy subjects, 8-17 years old, participated in a comprehensive psychobiologic study including three nights of EEG sleep recording. Each morning, subjects completed a post-sleep form subjectively rating their sleep, which was then compared with their polysomnographic studies.

RESULTS

Depressed subjects reported significantly worse sleep on four scales: subjective sleep quality, perceived number of awakenings, estimated minutes awake, and perceived ease of waking. In contrast to these subjective complaints, objective EEG measures indicated no evidence of disturbed sleep in the depressed sample compared to controls. Furthermore, exploratory analyses focusing on the subset of depressed subjects with the greatest subjective sleep disturbance showed, paradoxically, significantly better sleep in terms of the number of EEG awakenings and objective disturbances.

CONCLUSIONS

Despite clinical evidence of subjective sleep complaints in depressed children, our EEG measures showed little evidence to indicate an objective basis for these perceptions. These findings raise provocative questions regarding the nature of sleep complaints associated with early-onset depression.

Treatment enhances ultradian rhythms of CSF monoamine metabolites in patients with major depressive episodes

Unipolar and bipolar depressions show abnormal behavioral manifestations of ultradian (less than 24 h) rhythms, but abnormal rhythms of the central neurotransmitters thought to be important for depression pathophysiology (eg dopamine (DA) and serotonin (5-HT)) have not been shown in this time frame. Since antidepressant treatments normalize disrupted rhythms in depression (eg rapid-eye-movement sleep and hormonal rhythms), we hypothesized that depression-related changes in ultradian oscillations of DA and 5-HT might be revealed during antidepressant treatment. Cerebrospinal fluid (CSF) samples collected q10 min for 24 h in 13 patients experiencing major depressive episodes (MDE) before and after treatment for 5 weeks with sertraline or bupropion were assayed for levels of homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA), and their ratio was calculated. Data were analyzed in the frequency domain using Fourier transforms and multivariate permutation testing. Antidepressant treatments were associated with decreased variance for 5-HIAA, increased variance for HVA, and markedly increased variance for the HVA : 5-HIAA ratio (p<0.05, p<0.02, and p<0.003, respectively). With treatment, the correlations between 5-HIAA and HVA weakened (p=0.06). Power spectral density (PSD-the Fourier magnitude squared) of the 5-HIAA signals at periods of 1.75 and 3.7 h (both p<0.05) decreased, while circadian cycling of HVA levels (p<0.05) and of the ratio (p<0.005) increased after treatment. The PSD of the full-length HVA : 5-HIAA ratio series after treatment increased in rapid variability (20-103 min periods, p<0.05). Spectrographic windowing demonstrated a focal span of enhanced HVA : 5-HIAA ratio variability following antidepressant treatment, in an approximately 84-min period through the evening (p<0.05). Periodic neurotransmitter relationships in depressed patients were altered by treatment in this analysis of a small data set. This may represent a baseline abnormality in the regulation of periodic functions involved in the depression pathophysiology, but it could also be due to an unrelated antidepressant effect. Further studies including comparisons with healthy subject data are in progress.

Sleep and depression in children and adolescents

There is considerable research evidence suggesting that sleep is biologically linked to mood disorders in adults. However, polysomographic and neuroendocrine studies in children and adolescents have not found consistent changes in sleep architecture paralleling adult major depression. This review provides a detailed description of sleep research that has been conducted in early-onset affective disorders, uncovers the potential limitations of the available data, and formulates future research directions in this important subject.

Rest-activity cycles in childhood and adolescent depression

OBJECTIVE

To quantify circadian rhythms in rest-activity cycles in depressed children and adolescents.

METHOD

Rest-activity cycles were evaluated by actigraphy over five consecutive 24-hour periods in 100 children and adolescents, including 59 outpatients with major depressive disorder (MDD) and 41 healthy normal controls. Total activity, total light exposure, and time spent in light at more than 1,000 lux were averaged over the recording period for each participant. Time series analysis was used to determine the amplitude and period length of circadian rhythms in rest-activity.

RESULTS

Overall, adolescents with MDD had lower activity levels, damped circadian amplitude, and lower light exposure and spent less time in bright light than healthy controls. Among children, those with MDD showed lower light exposure and spent less time in bright light, but only depressed girls showed damped circadian amplitude. The sex differences were substantially greater in the MDD group than in the normal control group.

CONCLUSIONS

These results confirm damped circadian rhythms in children and adolescents with MDD and highlight the influence of gender and age on these measures.

The characteristics of asymptomatic female adolescents at high risk for depression: the baseline assessment from a prospective 8-year study

OBJECTIVES

This longitudinal 8-year study assesses potential predictors of major depressive disorder (MDD) in a cohort of healthy adolescent females at high familial risk for MDD. The objective of this study was to ascertain whether risk factors for female onset MDD would differentiate youth at high or usual risk for MDD, prior to the onset of depressive symptomology.

METHODS

Subjects (ages 12-15 years) were assigned to a high (n=43) or usual (n=40) risk group according to maternal history of MDD. Depressive symptomatology (Beck Depression Inventory, Hamilton Rating Scale for Depression), pubertal development (Pubertal Developmental Staging Questionnaire), social support (Social Support Scale), and cognitive vulnerability (Depressive Experiences Questionnaire) were assessed.

RESULTS

High risk and usual risk group demonstrated no significant differences in demographic variables such as age, body mass index, and grade. Significantly more youth in the high risk group (n=40, 93%) had started menstruation, compared to youth in the usual risk group (n=31, 77.5%). There were no significant differences between the groups on measures of dysphoric cognitive style, perceived overall number of social supports, or satisfaction with social support.

CONCLUSIONS

Females at high familial risk for the onset of depression have significant differences in pubertal development, but not in demographics, depressive symptoms, social supports, or dysphoric cognitive style, when compared to females at usual risk for depression. These findings suggest that in prevention trials for depression in asymptomatic young women no non-biological risk factors for MDD aid in identifying females at higher risk for MDD.

The effects of vagus nerve stimulation on sleep EEG in depression: a preliminary report

OBJECTIVE

The present study evaluated the effects of vagus nerve stimulation (VNS) on sleep in seven treatment-resistant depressed outpatients.

METHODS

Sleep studies were conducted in the laboratory at baseline and 10-12 weeks after VNS implantation while the concomitant psychotropic medication regimen was unchanged. Standard sleep macroarchitecture based on visual stage and assessment of ultradian sleep electroencephalographic (EEG) rhythms were measured on all nights.

RESULTS

An overall significant treatment effect on sleep macroarchitecture was obtained by MANOVA. Decreased awake time, decreased Stage 1 sleep and increased Stage 2 sleep were evident post-VNS, although univariate analyses did not reach significance. In addition, the strength or amplitude of ultradian sleep EEG rhythms more than doubled on VNS and was restored to within normal range.

CONCLUSION

VNS improved the clinical symptoms of depression and sleep architecture. Results suggest that treatment-resistant depressed patients have dampened sleep EEG rhythms that are restored to near-normal amplitudes with VNS treatment.

The roots of depression in adolescent girls: is menarche the key?

Before adolescence, the rates of depression are similar in girls and boys (or are slightly higher in boys). Yet with the onset of puberty, the gender proportion of depression dramatically shifts to a two girls to one boy ratio. What, then, is the relationship between menarche and the onset of major depression in early adolescence? Recent literature intimates that vulnerability to depression may be rooted in an intricate meld of genetic traits, normal female hormonal maturational processes, and gender socialization. Information regarding gender differences in the presentation of depressive symptoms is provided along with biologic, psychologic, and sociologic factors contributing to depression in adolescent girls. The burden of illness associated with onset of depression after menarche reinforces the importance of prevention or else expeditious recognition and intervention.

Propagation of repetitive alpha waves over the scalp in relation to subjective preferences for a flickering light

Paired-comparison tests were performed to examine subjective preferences for a flickering light. Electroencephalograms were then recorded from seven electrodes (10-20 system) during presentations of the most and least preferred flickering-light conditions. As a way of investigating the flow of alpha waves on the scalp over both the left and right hemispheres in relation to subjective preference, the alpha waves were analyzed by means of the cross-correlation function (CCF). The maximum value of the CCF, /phi(tau)/(max), between the alpha waves measured at different electrodes and its delay time, tau(m), were analyzed. Results show that the most preferred flickering light has a significant larger /phi(tau)/(max) than the least preferred flickering light, and that /phi(tau)/(max) decreases with increasing distance between comparison (O(1) or O(2)) and test electrodes. On the other hand, the delay time of the maximum value of the CCF, tau(m), increases with the distance between comparison and test electrodes.

Sleepiness in children and adolescents: clinical implications

Over the past decade, excessive sleepiness among children and adolescents has been identified as a major societal concern. Professionals working with pediatric groups must increasingly factor sleepiness into assessments of waking function. We define and discuss excessive sleepiness in children and adolescents and review available evidence regarding effects on behavior, mood, and performance. Findings for daytime sleepiness and subsequent impairment in these domains are classified as robust to unknown. Empirical evidence clearly indicates that children and adolescents experience significant daytime sleepiness as a result of inadequate or disturbed sleep. The specific effect of sleepiness on functional domains in pediatric groups are less well-studied, but existing data suggests that children are likely to experience impairment in behavioral, mood, and performance domains. However, such variables as developmental differences in the type and degree of impairment, the degree of sleep disturbance required to produce impairments, and potential risk and protective factors for the effects of sleepiness in children have yet to be described. Further research is clearly warranted, and we discuss important questions and methodological concerns to encourage inquiry in both clinical and experimental settings. Advice is offered with regard to screening for sleep problems and associated sleepiness with children and adolescents.

Temporal coherence in ultradian sleep EEG rhythms in a never-depressed, high-risk cohort of female adolescents

BACKGROUND

Previous work has indicated that low temporal coherence of ultradian sleep electroencephalographic rhythms is characteristic of depressed patients and of depressed women, in particular. It may also be evident in one quarter of those at high risk, based on a family history of depression.

METHODS

The present study evaluated temporal coherence of sleep electroencephalographic rhythms in 41 adolescent girls with a maternal history of depression (high risk) and 40 healthy controls (low risk). The entire sample was followed clinically every 6 months for 2 years.

RESULTS

Temporal coherence was significantly lower among the high-risk girls than in controls. Regression analyses predicted group from coherence values and correctly classified 70% of the high-risk group with a false-positive rate of 5% among controls. Moreover, 54% of the high-risk girls were identified with extreme low coherence. On clinical follow up, 14 girls showed depressive symptoms, 9 in the high-risk group (22.5%) and 5 controls (12.2%). Six met DSM-IV criteria for first-episode major depressive disorder, five high-risk and one control. Most importantly, 41% of those identified as having the most abnormal coherence values either showed symptoms of depression or met diagnostic criteria upon follow up.

CONCLUSIONS

Low temporal coherence is evident in adolescent girls at high risk for depression. The more abnormal the coherence, the greater the risk of a first episode of major depressive disorder within 2 years of sleep study, approximately 10 times greater than in controls.

Sleep EEG, depression and gender

Despite clear evidence of an intimate connection between sleep, major depressive disorders (MDD) and gender, few studies have explored gender differences in either sleep or in wakefulness in patients as a means of better understanding the psychogenic components of MDD. Indeed, few sleep studies focus on characterising gender differences in any population. This paper will present a review of the literature on gender differences in sleep and depression. The theoretical and clinical implications of the findings will also be discussed. The premise of the present review is that there is an inherent increased vulnerability to depression in women that arises out of basic gender differences in brain organisation and state regulation, particularly in response to a "biological challenge" during sleep. It is argued that the inherent properties of organisation and regulation of sleep EEG in healthy men and women, elicited under challenge conditions, show gender-specific vulnerability to organisational abnormalities that model homeostatic abnormalities in depressed men and women and contribute to the genesis of depression. 2001 Harcourt Publishers Ltd

Premorbid polysomnographic signs in depressed adolescents: a reanalysis of EEG sleep after longitudinal follow-up in adulthood

BACKGROUND

This is a report of a clinical follow-up study (10-15 years later as young adults) of adolescent major depressives and normal control subjects. Polysomnographic data were obtained during the original study period when the subjects were adolescent (time 1). With clinical follow-up (time 2) assessments in hand, our objective was to ascertain whether there were any premorbid polysomnographic signs associated with depression during adolescence.

METHODS

Based upon initial (during adolescence) and follow-up clinical assessments (as adults), new subject groupings were generated: depression-free normal subjects and original normal subjects who experienced a depressive episode during the follow-up period (latent depressives). Suicidality and recurrence of depression were also examined. Multivariate analysis of covariance was used to analyze group differences in sleep measures and logistic regression for predicting three outcomes: lifetime depression, lifetime suicidality, and recurrence.

RESULTS

Comparison of the depression-free normal subjects, the latent depressives, and the original major depressives revealed significant differences for sleep latency and sleep period time. Comparing all lifetime depressives (original major depressives and the latent depressives) to depression-free normal subjects revealed significantly more stages 3 and 4 combined (ST34) sleep and greater sleep period times among the depressives. An analysis involving the presence or absence of suicidality revealed no overall significant differences between the groups. Comparison of the lifetime depressives grouped by nonrecurrent and recurrent depressive course to the depression-free normal subjects revealed significant difference for sleep period time. Using logistic regression, we found that a longer sleep latency and sleep period time significantly predicted lifetime depression. Gender, ST34 sleep, and an interaction term for ST34 sleep and REM latency significantly predicted lifetime suicidality.

CONCLUSIONS

There was evidence of premorbid sleep abnormalities during adolescence. A general pattern of sleep disruption around sleep onset and during the first 100 min of the sleep period and overall sleep was evident among the major and lifetime depressives, involving sleep latency (initial insomnia), sleep period time (hypersomnia), REM latency, and slow-wave sleep. This adds to the body of literature that highlights the importance of the first 100 min of the sleep period in depression.

Delta sleep EEG in depressed adolescent females and healthy controls

BACKGROUND

Quantitative EEG studies have identified a number of sleep abnormalities in adults with major depressive disorders (MDD), including a reduction in the amplitude of delta activity during NREM sleep. To date, these methodologies have not been used in early onset MDD.

METHODS

Delta activity during NREM sleep was compared in eight symptomatic but unmedicated adolescent females with MDD and eight age- and gender-matched healthy controls.

RESULTS

The depressed group showed significantly lower delta amplitude and power in the first NREM sleep period. By contrast, standard sleep architecture did not differentiate between groups.

LIMITATIONS

Given the sample size, this study is best viewed as tentative. In addition, it has yet to be determined whether adolescent males with MDD also show delta sleep abnormalities. Further, failure to find between-group differences in REM latency or other macroarchitectural measures may be due to the small sample size.

CONCLUSIONS

The findings of this study underscore the utility of quantitative sleep EEG techniques in early onset MDD. The results of the present study do, however, diverge from reports in adults with MDD, where delta abnormalities are more prevalent in men. Such findings suggest that the maturational time course of sleep EEG disturbances may differ for males and females with depression. Early emergence of delta abnormalities in depression may be of relevance to clinical course of illness.

Sleep electroencephalographic coherence abnormalities in individuals at high risk for depression: a pilot study

BACKGROUND

Sleep electroencephalographic (EEG) studies of individuals with major depressive disorder have identified several microarchitectural features associated with the illness. These abnormalities are also found in clinically remitted individuals, raising the question of whether they are vulnerability markers of depression. This study evaluated the sleep EEG in high-risk individuals to see if abnormalities are present in the sleep EEG prior to the onset of illness.

METHODS

A total of 26 subjects (13 males and 13 females) were recruited for study on the basis of 1) having a parent or grandparent treated for major depressive or bipolar affective disorder and 2) having no history of personal psychiatric illness. Polysomnographic data were collected and compared with gender- and age-matched healthy control subjects with no personal or family history of psychiatric illness. The primary outcome measures were interhemispheric and intrahemispheric coherence.

RESULTS

Period analysis of the sleep EEG showed that beta-delta coherence was lower bilaterally in male high-risk subjects. Right-hemispheric theta-delta coherence was also lower in male high-risk subjects, with female high-risk subjects evidencing lower beta coherence.

CONCLUSIONS

Sleep-EEG abnormalities associated with major depressive disorder are present in never mentally ill individuals at high risk for the illness. These markers may be useful in the prediction of illness and in family genetic studies of mood disorders.