Célyne H. Bastien

Validation of the Insomnia Severity Index as an outcome measure for insomnia research

Background: Insomnia is a prevalent health complaint that is often difficult to evaluate reliably. There is an important need for brief and valid assessment tools to assist practitioners in the clinical evaluation of insomnia complaints.Objective: This paper reports on the clinical validation of the Insomnia Severity Index (ISI) as a brief screening measure of insomnia and as an outcome measure in treatment research. The psychometric properties (internal consistency, concurrent validity, factor structure) of the ISI were evaluated in two samples of insomnia patients.Methods: The first study examined the internal consistency and concurrent validity of the ISI in 145 patients evaluated for insomnia at a sleep disorders clinic. Data from the ISI were compared to those of a sleep diary measure. In the second study, the concurrent validity of the ISI was evaluated in a sample of 78 older patients who participated in a randomized-controlled trial of behavioral and pharmacological therapies for insomnia. Change scores on the ISI over time were compared with those obtained from sleep diaries and polysomnography. Comparisons were also made between ISI scores obtained from patients, significant others, and clinicians.Results: The results of Study 1 showed that the ISI has adequate internal consistency and is a reliable self-report measure to evaluate perceived sleep difficulties. The results from Study 2 also indicated that the ISI is a valid and sensitive measure to detect changes in perceived sleep difficulties with treatment. In addition, there is a close convergence between scores obtained from the ISI patients version and those from the clinicians and significant others versions.Conclusions: The present findings indicate that the ISI is a reliable and valid instrument to quantify perceived insomnia severity. The ISI is likely to be a clinically useful tool as a screening device or as an outcome measure in insomnia treatment research.

Cognitive-Behavioral Therapy for Insomnia: Comparison of Individual Therapy, Group Therapy, and Telephone Consultations.

Forty-five adults with primary insomnia received cognitive-behavioral therapy (CBT) implemented in a group therapy format, in individual face-to-face therapy or through brief individual telephone consultations. The results indicate that CBT was effective in improving sleep parameters with all 3 methods of treatment implementation, and there was no significant difference across methods of implementation. All 3 treatment modalities produced improvements in sleep that were maintained for 6 months after treatment completion. These results suggest that group therapy and telephone consultations represent cost-effective alternatives to individual therapy for the management of insomnia.

Prenatal exposure to polychlorinated biphenyls: a neuropsychologic analysis.

Objectives A large body of literature documents the effects of prenatal exposure to polychlorinated biphenyls (PCBs) on cognitive development of children. Despite this fact, no integrative synthesis has been published yet to identify the cognitive functions that are particularly affected. Our aim is to review this literature in an attempt to identify the cognitive profile associated with prenatal PCB exposure. Data sources Studies were identified by searching the PubMed database for articles published before June 2008. We reviewed data from nine prospective longitudinal birth cohorts for different aspects of cognition. Data extraction Associations between indicators of prenatal PCB exposure and performance on cognitive tasks reported in the selected studies are summarized and classified as general cognitive abilities, verbal or visual–spatial skills, memory, attention, and executive functions. Data synthesis The most consistent effects observed across studies are impaired executive functioning related to increased prenatal PCB exposure. Negative effects on processing speed, verbal abilities, and visual recognition memory are also reported by most studies. Converging results from different cohort studies in which exposure arises from different sources make it unlikely that co-exposure with another associated contaminant is responsible for the observed effects. Conclusion Prenatal PCB exposure appears to be related to a relatively specific cognitive profile of impairments. Failure to assess functions that are specifically impaired may explain the absence of effects found in some studies. Our findings have implications in the selection of cognitive assessment methods in future studies.

Precipitating factors of insomnia

Insomnia is a prevalent health complaint whose onset is precipitated by a variety of factors. There is an important need to identify and describe these factors to improve our understanding of risk factors and the natural history of insomnia. This article is aimed at identifying and describing the types of precipitating factors related to the onset of insomnia. A total of 345 patients evaluated for insomnia at a sleep-disorders clinic completed a sleep survey and underwent a semistructured clinical interview. As part of the evaluation, the specific precipitating events related to the onset of insomnia were identified. Subsequently, these factors were categorized (work-school, family, physical or psychological health, or indeterminate), and their affective valence (negative, positive, or indeterminate) was coded. The most common precipitating factors of insomnia were related to family, health, and work-school events. Sixty-five percent of precipitating events had a negative valence. These events differed with the age of onset of insomnia but not with the gender of participants. These findings are useful to identify potential risk factors for insomnia and improve our understanding of the natural history of insomnia.

Familial incidence of insomnia

This study evaluated the familial incidence of sleep disturbances among individuals with insomnia complaints. The sample consisted of 285 patients evaluated for insomnia at a sleep disorders clinic. All patients completed a sleep survey and underwent a semistructured clinical interview as part of their initial evaluation of insomnia. Information on the presence and nature of sleep disturbances among their family members (first‐ and second‐degree relatives) was obtained from a sleep survey. The findings indicate that 35% of patients consulting for insomnia had a positive family history of sleep disturbances. Insomnia was the most common type of sleep disturbance identified (76%) and the mother was the most frequently afflicted family member. Reports of sleep disturbances among a family member were more prevalent when the onset of insomnia was before 40‐years‐old than when it was later in life. A positive family history was slightly higher when the insomnia complaint involved sleep‐onset difficulties relative to sleep‐maintenance or mixed insomnias. Although the present findings suggest that a positive family history of insomnia may be a potential risk factor for insomnia, it is unclear whether this reflects a genetic predisposition or a social learning phenomenon.

Variability and predictability in sleep patterns of chronic insomniacs

Sleep of chronic insomniacs is often characterized by extensive night‐to‐night variability. To date, no study has examined this variability with long series of daily sleep data. The present study examined night‐to‐night variability with a sample of 106 participants meeting DSM‐IV diagnostic criteria for persistent primary insomnia. Participants completed daily sleep diaries for an average of 31 days (range: 18–56). Sleep efficiency, sleep onset latency and wake after sleep onset were derived from this measure. Despite evidence of extensive night variability, results showed that sleep patterns could be classified in three clusters. The first one was characterized by a high probability of having poor sleep, the second one by a low and decreasing probability, and the third one by a constant median probability of having a poor sleep, which is an unpredictable sleep pattern. In the first cluster, poor sleep was expected each night for patients with a predominance mixed insomnia including the three insomnia subtypes. In the second cluster, patients presented moderate insomnia, sleep‐onset latency below the threshold level and a predominance of sleep‐maintenance insomnia. In the third pattern, poor nights seemed unpredictable for patients with moderate to severe insomnia associated with the lowest proportion of sleep‐maintenance insomnia. Overall, sleep was predictable for about two‐thirds of individuals, whereas it was unpredictable for about one‐third. These findings confirm the presence of extensive variability in the sleep of chronic insomniacs and that poor sleep may be predictable for some of them. Additional research is needed to characterize those sleep patterns in terms of clinical features and temporal course.

Topography of age-related changes in sleep spindles.

Aging induces multiple changes to sleep spindles, which may hinder their alleged functional role in memory and sleep protection mechanisms. Brain aging in specific cortical regions could affect the neural networks underlying spindle generation, yet the topography of these age-related changes is currently unknown. In the present study, we analyzed spindle characteristics in 114 healthy volunteers aged between 20 and 73 years over 5 anteroposterior electroencephalography scalp derivations. Spindle density, amplitude, and duration were higher in young subjects than in middle-aged and elderly subjects in all derivations, but the topography of age effects differed drastically. Age-related decline in density and amplitude was more prominent in anterior derivations, whereas duration showed a posterior prominence. Age groups did not differ in all-night spindle frequency for any derivation. These results show that age-related changes in sleep spindles follow distinct topographical patterns that are specific to each spindle characteristic. This topographical specificity may provide a useful biomarker to localize age-sensitive changes in underlying neural systems during normal and pathological aging.

Evoked potential components unique to non-REM sleep: relationship to evoked K-complexes and vertex sharp waves

Following the loss of wakeful consciousness, the averaging of responses to stimuli produce evoked potential waveforms with prominent components either unique to or greatly enhanced by non-REM sleep. In the sleep onset periods (stage 1) these are the P2 and N350. Following the establishment of stable sleep (stage 2 and SWS), the N550 and P900 are also prominent. Investigation of the EEG associated with individual responses indicates that a good proportion of stimuli elicit, K-complexes or vertex sharp waves (VSWs) and occasionally will elicit both. Recent work has indicated that the N550 in the averaged response is due to the presence of K-complexes and that the N350 is at least largely due to the presence of VSWs. The large size of these grapho-elements indicates that they are probably produced by a synchronized discharge of multiple neural units. Both are readily observed in the absence of external stimulation and occur as normal components of sleep, indeed the K-complex is used as one of the identifying features of the onset of stable non-REM sleep. The present review details the investigation of these features and their associated evoked potential components, in terms of stimulus features, brain states associated with their production, their scalp topography, and changes as a function of age.

Prenatal exposure to methylmercury and PCBs affects distinct stages of information processing: An event-related potential study with Inuit children

Methylmercury (MeHg) and polychlorinated biphenyls (PCBs) are seafood contaminants known for their adverse effects on neurodevelopment. This study examines the relation of developmental exposure to these contaminants to information processing assessed with event-related potentials (ERPs) in school-aged Inuit children from Nunavik (Arctic Québec). In a prospective longitudinal study on child development, exposure to contaminants was measured at birth and 11 years of age. An auditory oddball protocol was administered at 11 years to measure ERP components N1 and P3b. Multiple regression analyses were performed to examine the associations of levels of the contaminants to auditory oddball performance (mean reaction time, omission errors and false alarms) and ERP parameters (latency and amplitude) after control for potential confounding variables. A total of 118 children provided useable ERP data. Prenatal MeHg exposure was associated with slower reaction times and fewer false alarms during the oddball task. Analyses of the ERP parameters revealed that prenatal MeHg exposure was related to greater amplitude and delayed latency of the N1 wave in the target condition but not to the P3b component. MeHg effects on the N1 were stronger after control for seafood nutrients. Prenatal PCB exposure was not related to any endpoint for sample as a whole but was associated with a decrease in P3b amplitude in the subgroup of children who had been breast-fed for less than 3 months. Body burdens of MeHg and PCBs at 11 years were not related to any of the behavioural or ERP measures. These data suggest that prenatal MeHg exposure alters attentional mechanisms modulating early processing of sensory information. By contrast, prenatal PCB exposure appears to affect information processing at later stages, when the information is being consciously evaluated. These effects seem to be mitigated in children who are breast-fed for a more extended period.

The natural history of insomnia: Focus on prevalence and incidence of acute insomnia

Despite Acute Insomnia being classified as a distinct nosological entity since 1979/1980 (ASDC/DSM III-R), there are no published estimates of its prevalence and incidence or data regarding transition to chronic insomnia or remission. This lack of data prevents an understanding of: a) the pathogenesis of insomnia and b) when and how treatment should be initiated. The aim of the present study was to provide such data from two community samples. Samples were recruited in the USA (n = 2861) and the North East of the UK (n = 1095). Additionally, 412 Normal Sleepers from the UK sample were surveyed longitudinally to determine prospectively incidence, transition, and remission rates for acute insomnia and assess whether the acute insomnia was a first episode, recurrent episode, or co-morbid with symptoms of other illnesses. The prevalence of acute insomnia was 9.5% (USA) and 7.9%(UK). The prevalence of three acute insomnia subtypes in the UK were; First-Onset Acute Insomnia 2.6%; Recurrent Acute Insomnia 3.8%; and 1.4% Co-morbid Acute Insomnia. The annual incidence of acute insomnia in the UK sample was between 31.2% and 36.6%. Remission rates fluctuated depending upon the definition of acute insomnia and whether the current episode was first-onset or recurrent. These findings provide preliminary insights into the natural history of insomnia. Such data will serve to inform how and when acute insomnia should be managed and whether such interventions may serve to diminish subsequent morbidity, particularly with respect to Major Depression.