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Fernandez-Mendoza J, Calhoun SL, Bixler EO. Edward O. Bixler, PhD: from the Apollo project and chimpanzees to sleep epidemiology. SLEEP ADVANCES : A JOURNAL OF THE SLEEP RESEARCH SOCIETY 2024; 5:zpae020. [PMID: 38562675 PMCID: PMC10983785 DOI: 10.1093/sleepadvances/zpae020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 01/26/2024] [Indexed: 04/04/2024]
Abstract
What an honor to write about Dr. Edward O. Bixler's contributions to the sleep field. In 1967, Dr. Bixler published a case report on a chimpanzee with implanted brain electrodes while working at an Air Force base in New Mexico. A few years later, in 1971, he published on the sleep effects of flurazepam in individuals with insomnia together with Dr. Anthony Kales, data that he had collected when the Sleep Research & Treatment Center (SRTC) was housed at the University of California Los Angeles. Dr. Bixler, a meticulous scientist, learned from Dr. Kales, a devoted clinician, to study "the whole patient, and all aspects of sleep," a legacy that continued when the SRTC moved to Penn State in Hershey. Indeed, Dr. Bixler's tenure at Penn State from 1971 until 2019 kept the science of the SRTC focused on that premise and helped translate scientific evidence into clinical care. He not only contributed early to the pharmacology of sleep and the effects of hypnotics, but he was also a pioneer in "sleep epidemiology." His "Prevalence of sleep disorders in the Los Angeles metropolitan area" study of 1979 was the first rigorous epidemiological study on sleep disturbances. Starting in 1990, he established the Penn State Adult Cohort to estimate the prevalence and natural history of sleep-disordered breathing and other sleep disorders in adults. Inspired by life-course epidemiology, he established in 2001 the Penn State Child Cohort to estimate the same phenomena in children. This Living Legend paper captures and highlights Dr. Bixler's enduring legacy to sleep science.
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Affiliation(s)
- Julio Fernandez-Mendoza
- Sleep Research & Treatment Center, Department of Psychiatry and Behavioral Health, Penn State College of Medicine, Hershey, PA, USA
| | - Susan L Calhoun
- Sleep Research & Treatment Center, Department of Psychiatry and Behavioral Health, Penn State College of Medicine, Hershey, PA, USA
| | - Edward O Bixler
- Sleep Research & Treatment Center, Department of Psychiatry and Behavioral Health, Penn State College of Medicine, Hershey, PA, USA
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Vojnits B, Magyar TZ, Szalárdy O, Reicher V, Takács M, Bunford N, Bódizs R. Mobile sleep EEG suggests delayed brain maturation in adolescents with ADHD: A focus on oscillatory spindle frequency. RESEARCH IN DEVELOPMENTAL DISABILITIES 2024; 146:104693. [PMID: 38324945 DOI: 10.1016/j.ridd.2024.104693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 11/21/2023] [Accepted: 01/28/2024] [Indexed: 02/09/2024]
Abstract
BACKGROUND Attention-deficit/hyperactivity disorder (ADHD) is a prevalent neurodevelopmental disorder. Although data show ADHD is associated with sleep problems, approaches to analyze the association between ADHD and sleep electrophysiology are limited to a few methods with circumscribed foci. AIMS Sleep EEG was analyzed by a mixed-radix FFT routine and power spectrum parametrization in adolescents with ADHD and adolescents not at-risk for ADHD. Spectral components of sleep EEG were analyzed employing a novel, model-based approach of EEG power spectra. METHODS AND PROCEDURES The DREEM mobile polysomnography headband was used to record home sleep EEG from 19 medication-free adolescents with ADHD and 29 adolescents not at-risk for ADHD (overall: N = 56, age range 14-19 years) and groups were compared on characteristics of NREM sleep. OUTCOMES AND RESULTS Adolescents with ADHD exhibited lower frequency of spectral peaks indicating sleep spindle oscillations whereas adolescents not at-risk for ADHD showed lower spectral power in the slow sleep spindle and beta frequency ranges. CONCLUSIONS AND IMPLICATIONS The observed between-groups difference might indicate delayed brain maturity unraveled during sleep in ADHD.
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Affiliation(s)
- Blanka Vojnits
- Institute of Behavioural Science, Semmelweis University, Budapest, Hungary.
| | - Tárek Zoltán Magyar
- Institute of Behavioural Science, Semmelweis University, Budapest, Hungary; Institute of Psychology, Pázmány Péter Catolic University, Budapest, Hungary
| | - Orsolya Szalárdy
- Institute of Behavioural Science, Semmelweis University, Budapest, Hungary; Research Centre for Natural Sciences Institute of Cognitive Neuroscience and Psychology, Sound and Speech Perception Research Group, Budapest, Hungary
| | - Vivien Reicher
- HUN-REN Research Centre for Natural Sciences Institute of Cognitive Neuroscience and Psychology, Clinical and Developmental Neuropsychology Research Group, Budapest, Hungary
| | - Mária Takács
- Institute of Behavioural Science, Semmelweis University, Budapest, Hungary
| | - Nóra Bunford
- HUN-REN Research Centre for Natural Sciences Institute of Cognitive Neuroscience and Psychology, Clinical and Developmental Neuropsychology Research Group, Budapest, Hungary
| | - Róbert Bódizs
- Institute of Behavioural Science, Semmelweis University, Budapest, Hungary
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Campbell IG, Figueroa JG, Bottom VB, Cruz-Basilio A, Zhang ZY, Grimm KJ. Maturational trend of daytime sleep propensity in adolescents. Sleep 2024; 47:zsad263. [PMID: 37798133 DOI: 10.1093/sleep/zsad263] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 08/30/2023] [Indexed: 10/07/2023] Open
Abstract
STUDY OBJECTIVES The teenage increase in sleepiness is not simply a response to decreasing nighttime sleep duration. Daytime sleepiness increases across adolescence even when prior sleep duration is held constant. Here we determine the maturational trend in daytime sleep propensity assessed with the multiple sleep latency test (MSLT) and assess the trend's relation to pubertal maturation and changes in the sleep electroencephalogram. We also evaluate whether the relation of daytime sleep propensity to prior sleep duration changes between ages 10 and 23 years. METHODS Participants (n = 159) entered the study between ages 9.8 and 22.8 years and were studied annually for up to 3 years. Annually, participants kept each of three sleep schedules in their homes: 7, 8.5, and 10 hours in bed for 4 consecutive nights with polysomnography on nights 2 and 4. MSLT-measured daytime sleep propensity was assessed in the laboratory on the day following the fourth night. RESULTS A two-part linear spline model described the maturation of daytime sleep propensity. MSLT sleep likelihood increased steeply until age 14.3 years, after which it did not change significantly. The maturational trend was strongly associated with the adolescent decline in slow-wave (delta, 1-4 Hz) EEG power during NREM sleep and with pubertal maturation assessed with Tanner stage measurement of breast/genital development. The effect of prior sleep duration on sleep likelihood decreased with age. CONCLUSIONS Adolescent brain changes related to pubertal maturation and those reflected in the delta decline contribute to the adolescent increase in daytime sleep propensity.
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Affiliation(s)
- Ian G Campbell
- Department of Psychiatry and Behavioral Sciences, University of California Davis, Sacramento, CA, USA
| | - Jessica G Figueroa
- Department of Psychiatry and Behavioral Sciences, University of California Davis, Sacramento, CA, USA
| | - Vincent B Bottom
- Department of Psychiatry and Behavioral Sciences, University of California Davis, Sacramento, CA, USA
| | - Alejandro Cruz-Basilio
- Department of Psychiatry and Behavioral Sciences, University of California Davis, Sacramento, CA, USA
- Department of Psychology, Northwestern University, Evanston, IL, USA
| | - Zoey Y Zhang
- Department of Psychiatry and Behavioral Sciences, University of California Davis, Sacramento, CA, USA
| | - Kevin J Grimm
- Department of Psychology, Arizona State University, Tempe, AZ, USA
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Ricci A, Fernandez-Mendoza J. Evidence of how the maturing sleeping brain contributes to the sleepy brain of adolescents. Sleep 2024; 47:zsad283. [PMID: 37935893 PMCID: PMC10782484 DOI: 10.1093/sleep/zsad283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Indexed: 11/09/2023] Open
Affiliation(s)
- Anna Ricci
- Department of Neurological Sciences, Robert Larner M.D. College of Medicine, University of Vermont, Burlington, VT, USA
| | - Julio Fernandez-Mendoza
- Sleep Research and Treatment Center, Department of Psychiatry and Behavioral Health, Penn State Health Milton S. Hershey Medical Center, Penn State University College of Medicine, Hershey, PA, USA
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Campbell IG, Cruz-Basilio A, Figueroa JG, Bottom VB. Earlier Bedtime and Its Effect on Adolescent Sleep Duration. Pediatrics 2023; 152:e2022060607. [PMID: 37305962 PMCID: PMC10312236 DOI: 10.1542/peds.2022-060607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/24/2023] [Indexed: 06/13/2023] Open
Abstract
BACKGROUND AND OBJECTIVES Sleep duration decreases by ∼10 minutes per year throughout adolescence. A circadian phase delay and changes in homeostatic sleep regulation enable adolescents to stay up later. We determine if teens are able to increase sleep duration by advancing bedtime and whether this ability changes with age. METHODS A younger cohort of 77 participants ranging in age from 9.9 to 16.2 years were studied annually for 3 years. An older cohort of 67 participants ranging in age from 15.0 to 20.6 years was studied only once. Annually, participants kept each of 3 different time in bed (TIB) schedules (7, 8.5, and 10 hours) for 4 consecutive nights. Participants kept their habitual weekday rise times; TIB was altered by advancing bedtimes. We report polysomnography-measured sleep durations from the fourth night of the TIB schedule. RESULTS Despite increases in sleep onset latency and wake after sleep onset, sleep duration increased with TIB as bedtime was advanced. Average (SE) sleep duration increased from 402.8 (1.6) minutes with 7 hours to 470.6 (2.1) minutes with 8.5 hours to 527.5 (3.0) minutes with 10 hours TIB. Sleep duration decreased with age (1.55 [0.48] minutes/year), but the TIB effect on sleep duration did not (TIB by age interaction, P = .42). CONCLUSIONS Adolescents can substantially increase sleep duration by advancing bedtime, and this ability does not change between ages 10 and 21 years. Additional research is needed to determine how to translate these findings from experiment-controlled sleep schedules to real-world sleep duration increases.
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Affiliation(s)
- Ian G. Campbell
- Department of Psychiatry and Behavioral Sciences, University of California, Davis, Sacramento, California
| | - Alejandro Cruz-Basilio
- Department of Psychiatry and Behavioral Sciences, University of California, Davis, Sacramento, California
- Department of Psychology, Northwestern University, Evanston, Illinois
| | - Jessica G. Figueroa
- Department of Psychiatry and Behavioral Sciences, University of California, Davis, Sacramento, California
| | - Vincent B. Bottom
- Department of Psychiatry and Behavioral Sciences, University of California, Davis, Sacramento, California
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Castelnovo A, Lividini A, Riedner BA, Avvenuti G, Jones SG, Miano S, Tononi G, Manconi M, Bernardi G. Origin, synchronization, and propagation of sleep slow waves in children. Neuroimage 2023; 274:120133. [PMID: 37094626 DOI: 10.1016/j.neuroimage.2023.120133] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 03/30/2023] [Accepted: 04/21/2023] [Indexed: 04/26/2023] Open
Abstract
STUDY OBJECTIVES Sleep slow wave activity, as measured using EEG delta power (<4 Hz), undergoes significant changes throughout development, mirroring changes in brain function and anatomy. Yet, age-dependent variations in the characteristics of individual slow waves have not been thoroughly investigated. Here we aimed at characterizing individual slow wave properties such as origin, synchronization, and cortical propagation at the transition between childhood and adulthood. METHODS We analyzed overnight high-density (256 electrodes) EEG recordings of healthy typically developing children (N=21, 10.3±1.5 years old) and young healthy adults (N=18, 31.1±4.4 years old). All recordings were preprocessed to reduce artifacts, and NREM slow waves were detected and characterized using validated algorithms. The threshold for statistical significance was set at p=0.05. RESULTS The slow waves of children were larger and steeper, but less widespread than those of adults. Moreover, they tended to mainly originate from and spread over more posterior brain areas. Relative to those of adults, the slow waves of children also displayed a tendency to more strongly involve and originate from the right than the left hemisphere. The separate analysis of slow waves characterized by high and low synchronization efficiency showed that these waves undergo partially distinct maturation patterns, consistent with their possible dependence on different generation and synchronization mechanisms. CONCLUSIONS Changes in slow wave origin, synchronization, and propagation at the transition between childhood and adulthood are consistent with known modifications in cortico-cortical and subcortico-cortical brain connectivity. In this light, changes in slow-wave properties may provide a valuable yardstick to assess, track, and interpret physiological and pathological development.
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Affiliation(s)
- Anna Castelnovo
- Sleep Medicine Unit, Neurocenter of Southern Switzerland, Ospedale Civico, Lugano, Switzerland; Faculty of Biomedical Sciences, Università della Svizzera Italiana, Lugano, Switzerland; University Hospital of Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland.
| | - Althea Lividini
- Epilepsy Center - Sleep Medicine Center, Childhood and Adolescence Neuropsychiatry Unit, ASST SS. Paolo e Carlo, San Paolo Hospital, Milan, Italy
| | - Brady A Riedner
- Center for Sleep and Consciousness, Department of Psychiatry, University of Wisconsin - Madison, Madison, WI, USA
| | - Giulia Avvenuti
- MoMiLab Research Unit, IMT School for Advanced Studies Lucca, Lucca, Italy
| | - Stephanie G Jones
- Department of Psychiatry, Wisconsin Institute for Sleep and Consciousness, University of Wisconsin-Madison(,) Madison, WI, USA
| | - Silvia Miano
- Sleep Medicine Unit, Neurocenter of Southern Switzerland, Ospedale Civico, Lugano, Switzerland; Faculty of Biomedical Sciences, Università della Svizzera Italiana, Lugano, Switzerland
| | - Giulio Tononi
- Department of Psychiatry, Wisconsin Institute for Sleep and Consciousness, University of Wisconsin-Madison(,) Madison, WI, USA
| | - Mauro Manconi
- Sleep Medicine Unit, Neurocenter of Southern Switzerland, Ospedale Civico, Lugano, Switzerland; Faculty of Biomedical Sciences, Università della Svizzera Italiana, Lugano, Switzerland; Department of Neurology, University Hospital, Inselspital, Bern, Switzerland
| | - Giulio Bernardi
- MoMiLab Research Unit, IMT School for Advanced Studies Lucca, Lucca, Italy.
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Langenberg SCN, Kocevska D, Luik AI. The multidimensionality of sleep in population‐based samples: a narrative review. J Sleep Res 2022; 31:e13608. [PMID: 35429087 PMCID: PMC9339471 DOI: 10.1111/jsr.13608] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 03/25/2022] [Accepted: 03/25/2022] [Indexed: 12/03/2022]
Abstract
The identification of optimal sleep duration recommendations for the general population has long been an important goal on the public health agenda, as both short and long sleep duration have been linked to unfavourable health outcomes. Yet, sleep is more than duration alone and can be described across multiple domains, such as timing, regularity, satisfaction, alertness, and efficiency. We reviewed observational population‐based studies that examined differences in age, sex, and origin across multiple dimensions of sleep. Reviewed literature suggests an increasing prevalence of insomnia symptoms, shorter and less deep sleep in old age. Overall, women report poorer sleep quality than men despite objective measures revealing shorter and more fragmented sleep in men. Minorities generally have poorer quantity and quality of sleep, but multi‐ethnic studies have reported mixed results regarding the subjective experience of sleep. In sum, effects of age, sex and origin differ across sleep dimensions, thereby suggesting that the multidimensionality of sleep and how these different aspects interact should be studied across individuals. Studies should include both self‐reported measures and objective assessments in diverse population‐based samples, as both aspects are important to understand sleep health in the general population. Data‐driven descriptions could provide researchers and clinicians with insights into how well individuals are sleeping and offer concrete targets for promotion of sleep health across the population.
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Affiliation(s)
| | - Desana Kocevska
- Department of Epidemiology Erasmus MC University Medical Center Rotterdam the Netherlands
- Department of Sleep and Cognition Netherlands Institute for Neuroscience Amsterdam the Netherlands
| | - Annemarie I. Luik
- Department of Epidemiology Erasmus MC University Medical Center Rotterdam the Netherlands
- Department of Child and Adolescent Psychiatry/Psychology Erasmus MC University Medical Center Rotterdam the Netherlands
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Ricci A, Calhoun SL, He F, Fang J, Vgontzas AN, Liao D, Bixler EO, Younes M, Fernandez-Mendoza J. Association of a novel EEG metric of sleep depth/intensity with attention-deficit/hyperactivity, learning, and internalizing disorders and their pharmacotherapy in adolescence. Sleep 2022; 45:zsab287. [PMID: 34888687 PMCID: PMC8919202 DOI: 10.1093/sleep/zsab287] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 11/17/2021] [Indexed: 01/08/2023] Open
Abstract
STUDY OBJECTIVES Psychiatric/learning disorders are associated with sleep disturbances, including those arising from abnormal cortical activity. The odds ratio product (ORP) is a standardized electroencephalogram metric of sleep depth/intensity validated in adults, while ORP data in youth are lacking. We tested ORP as a measure of sleep depth/intensity in adolescents with and without psychiatric/learning disorders. METHODS Four hundred eighteen adolescents (median 16 years) underwent a 9-hour, in-lab polysomnography. Of them, 263 were typically developing (TD), 89 were unmedicated, and 66 were medicated for disorders including attention-deficit/hyperactivity (ADHD), learning (LD), and internalizing (ID). Central ORP during non-rapid eye movement (NREM) sleep was the primary outcome. Secondary/exploratory outcomes included central and frontal ORP during NREM stages, in the 9-seconds following arousals (ORP-9), in the first and second halves of the night, during REM sleep and wakefulness. RESULTS Unmedicated youth with ADHD/LD had greater central ORP than TD during stage 3 and in central and frontal regions during stage 2 and the second half of the sleep period, while ORP in youth with ADHD/LD on stimulants did not significantly differ from TD. Unmedicated youth with ID did not significantly differ from TD in ORP, while youth with ID on antidepressants had greater central and frontal ORP than TD during NREM and REM sleep, and higher ORP-9. CONCLUSIONS The greater ORP in unmedicated youth with ADHD/LD, and normalized levels in those on stimulants, suggests ORP is a useful metric of decreased NREM sleep depth/intensity in ADHD/LD. Antidepressants are associated with greater ORP/ORP-9, suggesting these medications induce cortical arousability.
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Affiliation(s)
- Anna Ricci
- Sleep Research and Treatment Center, Department of Psychiatry and Behavioral Health, Penn State College of Medicine, Hershey, PA,USA
| | - Susan L Calhoun
- Sleep Research and Treatment Center, Department of Psychiatry and Behavioral Health, Penn State College of Medicine, Hershey, PA,USA
| | - Fan He
- Department of Public Health Sciences, Penn State College of Medicine, Hershey, PA, USA
| | - Jidong Fang
- Sleep Research and Treatment Center, Department of Psychiatry and Behavioral Health, Penn State College of Medicine, Hershey, PA,USA
| | - Alexandros N Vgontzas
- Sleep Research and Treatment Center, Department of Psychiatry and Behavioral Health, Penn State College of Medicine, Hershey, PA,USA
| | - Duanping Liao
- Department of Public Health Sciences, Penn State College of Medicine, Hershey, PA, USA
| | - Edward O Bixler
- Sleep Research and Treatment Center, Department of Psychiatry and Behavioral Health, Penn State College of Medicine, Hershey, PA,USA
| | - Magdy Younes
- Sleep Disorders Centre, Department of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Julio Fernandez-Mendoza
- Sleep Research and Treatment Center, Department of Psychiatry and Behavioral Health, Penn State College of Medicine, Hershey, PA,USA
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Evidence of a maturational disruption in non-rapid eye movement sleep slow wave activity in youth with attention-deficit/hyperactivity, learning and internalizing disorders. Sleep Med 2022; 90:230-237. [PMID: 35217303 PMCID: PMC8923949 DOI: 10.1016/j.sleep.2022.01.026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 01/13/2022] [Accepted: 01/31/2022] [Indexed: 11/23/2022]
Abstract
BACKGROUND Sleep slow wave activity (SWA) peaks during childhood and declines in the transition to adolescence during typical development (TD). It remains unknown whether this trajectory differs in youth with neuropsychiatric disorders. METHODS We analyzed sleep EEGs of 664 subjects 6 to 21 y (449 TD, 123 unmedicated, 92 medicated) and 114 subjects 7-12 y (median 10.5 y) followed-up at 18-22 y (median 19 y). SWA (0.4-4 Hz) power was calculated during non-rapid eye movement sleep. RESULTS TD and unmedicated youth showed cubic central and frontal SWA trajectories from 6 to 21 y (p-cubic<0.05), with TD youth showing peaks in central SWA at 6.8 y and frontal at 8.2 y. Unmedicated attention-deficit/hyperactivity (ADHD) and/or learning disorders (LD) showed peak central SWA 2 y later (at 9.6 y, coinciding with peak frontal SWA) than TD, followed by a 67% steeper slope by 19 y. Frontal SWA peak and slope in unmedicated ADHD/LD, and that of central and frontal in internalizing disorders (ID), were similar to TD. Unmedicated ADHD/LD did not differ in the longitudinal SWA percent change by 18-22 y; unmedicated ID showed a lower longitudinal change in frontal SWA than TD. Medicated youth showed a linear decline in central and frontal SWA from 6 to 21 y (p-linear<0.05). CONCLUSIONS ADHD/LD youth show a maturational delay and potential topographical disruption in SWA during childhood and steeper decline throughout adolescence, suggesting faster synaptic pruning. Youth with ID experience less changes in frontal SWA by late adolescence. Psychotropic medications may impact the maturational trajectory of SWA, but not the magnitude of developmental decline by late adolescence.
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Sex and Pubertal Differences in the Maturational Trajectories of Sleep Spindles in the Transition from Childhood to Adolescence: A Population-Based Study. eNeuro 2021; 8:ENEURO.0257-21.2021. [PMID: 34168053 PMCID: PMC8281264 DOI: 10.1523/eneuro.0257-21.2021] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 06/10/2021] [Indexed: 11/21/2022] Open
Abstract
Sleep spindles, bursts of electroencephalogram (EEG) activity in the σ-frequency (11–16 Hz) range, may be biomarkers of cortical development. Studies capturing the transition to adolescence are needed to delineate age-related, sex-related, and pubertal-related changes in sleep spindles at the population-level. We analyzed the sleep EEG of 572 subjects 6–21 years (48% female) and 332 subjects 5–12 years (46% female) followed-up at 12–22 years. From 6 to 21 years, spindle density (p quadratic = 0.019) and fast (12–16 Hz) spindle percent (p quadratic = 0.016) showed inverted U-shaped trajectories, with plateaus after 15 and 19 years, respectively. Spindle frequency increased (p linear < 0.001), while spindle power decreased (p linear < 0.001) from 6 to 21 years. The trajectories of spindle density, frequency, and fast spindle percent diverged between females and males, in whom density plateaued by 14 years, fast spindle percent by 16 years, and frequency by 18 years, while fast spindle percent and spindle frequency continued to increase until 21 years in females. Males experienced a longitudinal increase in spindle density 31% greater than females by 12–14 years (p = 0.006). Females experienced an increase in spindle frequency and fast spindle percent 2% and 41% greater, respectively, than males by 18–22 years (both p = 0.004), while males experienced a 14% greater decline in spindle power by 18–22 years (p = 0.018). Less mature adolescents (86% male) experienced a longitudinal increase in spindle density 36% greater than mature adolescents by 12–14 years (p = 0.002). Overall, males experience greater maturational changes in spindle density in the transition to adolescence, driven by later pubertal development, and sex differences become prominent in early adulthood when females have greater spindle power, frequency, and fast spindle percent.
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