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Nightmare disorder in light of neuropsychological and polysomnographic investigations

This study explores the characteristics, prevalence, comorbidity, and underlying factors of Nightmare Disorder through neuropsychological and polysomnographic investigations. Findings suggest a potential link between emotional regulation, personality traits, and sleep quality.

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Nightmare disorder in light of neuropsychological and polysomnographic investigations

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  1. Nightmare disorder in light of neuropsychological andpolysomnographic investigations Péter Simor Budapest University of Technology and Economics, Department of Cognitive Sciences

  2. Nightmare disorder • Intense, disturbing mental experiences that often awaken the dreamer (from REM or late night NREM sleep) • Weekly basis • Detailed, vivid recall of the emotionally negative dream experience • Alertness is full immediately on awakening, with little confusion or disorientation • The dream experience causes clinically significant distress or impairment in social, occupational, or other important domains DSM-IV-TR, 2000; ICSD-II, 2005

  3. Prevalence • Epidemiology (2-6%) • Adults vs Children (4 % vs. 30%) • Nightmares across the lifespan Nielsen & Zadra (2010)

  4. PTSD vs. Idiopathic Nightmares • Nightmare topics: • Falling • Being chased • Paralyzed • Threatening sorroundings • Death of close persons • Being attacked physically • Unable to complete a task • Accident • Threatening animals • Natural disasters • Schredl (2010)

  5. Psychiatric perspective Co-morbidity with mental complaints PTSD BPD Depression Anxiety Schizotipy Dissociation Suicide Tendencies Sleep Medicine Perspective Co-morbidity is not evident if we examine mental complaints among a group of nightmare sufferers instead of the other way around Mediating factors Nightmare distress Personality Secondary symptom or Core Sleep Disorder? Spoormaker et al. (2006, 2008)

  6. Independence of nightmares from mental complaints • PTSD: nightmares persist after the remission of waking symptoms (Montgomery et al, 2005) • Dream Logs: occurence of nightmares is not related to daily variations of anxiety symptoms (Wood et al, 1990) • Genetic studies: The high genetic heritability of nightmares is independent of the heritability of anxiety symptoms (Coolidge et al, 2010)

  7. Personality • Day-dreaming, imagination, creativity • Neuroticism, emotional vulnerability • Opennes to experience • Difficulty in separating the content of different mental states (past-present, reality-fantasy, self and the other, etc.) • Increased dream recall • More complex, bizarre, intense dreams • Nightmares • Lucid dreams

  8. Levin&Nielsen, 2007

  9. Emotional regulation and sleep • Emotional decoupling • Neural reorganization of emotional memory representations Walker, 2009 • Amigdalar over-reactivity • Inefficient prefrontal inhibitory control • Failure in emotional regulation, emotional memory organization • Dysphoric dreaming 4. Levin & Nielsen, 2007

  10. Behavioural studies • Selection of participants: • (35 NM, 35 matched CO sujects) • Questionnaires: • GSQS – Subjective Sleep Quality (Simor et al, 2009) • Anxiety – STAI-T (Spielberger, 1970) • Neuropsychological testing: • Emotional Go/noGO task • Emotional (verbal) Stroop task • Verbal Fluency Task failure coffe death glass miserable telephone accident umbrella killer seller

  11. Go/no GO task: neutral targets and emotional distractors Group: F = 4,3 p = 0,04 Valence: F = 4,4 p = 0,04 BUT: the group effect is mediated by levels of anxiety (STAI-T scores) NM CO Simor et al. (2012) Brain and Cognition

  12. Emotional Stroop task (mixed design) Group effect was independent of the effect of STAI-T and Sleep Quality Simor et al. (2012) Brain and Cognition

  13. Study 2. Block design Stroop task and classical (color-word) stroop task (19 NM, 17 CO) - Main effect of group - Emotional interference in both groups NO group difference in either condition of the classical color-word stroop task Simor et al. (2012) Brain Cogn

  14. Verbal Fluency task • Impaired executive functions in nightmare disorder • Differences are not unequivocally mediated by increased anxiety levels • Specificity? • The role of Sleep? Causal inferences? Simor et al. (2012) Brain Cogn

  15. Altered sleep and nightmare frequency • Nightmares are associated with poor subjective sleep quality (Li et al, 2011; Schredl, 2003) • Higher rate of nightmares in sleep disordered (insomnia, REM behavior disorder, Narcolepsy) patients • Nightmares are related to the subjective severity of sleep problems (Krakow 2006) • Few studies investigating objctive sleep parameters (small sample size, without controlling the confounding factors)

  16. 17 NM and 23 CO subjects spent 2 consecutive nights in the sleep laboratory. The sleep architecture based on the undisturbed full-night recording of the second night was examined. We controlled for the effects of STAI-T and BDI (depression) scores on our dependent variables Fragmented sleep in nightmare disorder p = 0.018 p =0.027 p = 0.002 p =0.007

  17. p = 0.48 p = 0.005 STAI, BDI-H Imbalance of sleep promoting and arousing influences during sleep? Simor, Horváth et al (2012) Eur Arch Psych Clin Neurosci

  18. Nightmare Disorder and the Cyclic Alternating Pattern (CAP) To sleep or not to sleep? Parrino et al, 2012

  19. CAP A subtypes A3 (alpha, 8-12 Hz) A1 (delta 0.25-4 Hz) • sleep protecting mechanism • related to off-line information processing • related to increased waking executive functions (prefrontal cortex) • preparation for awakening • open state towards the environment • related to decreased waking executive functions (prefrontal cortex)

  20. CAP A2 (mixture of fast and slow activations) Delta activity Alpha activity • mixture of sleep preserving and arousing mechanisms • related to decreased waking executive functions

  21. Imbalance of sleep promoting and arousing influences Simor et al. (2013) SLEEP

  22. And what about REM sleep? NS Increased arousal processes are only evident in NREM sleep Arousals in REM sleep did not differ Limits of visual scoring?

  23. Relative spectral power analyses (19 NM, 21 CO)NREM, REM periods Cz electrode 7.75-9 Hz 10-14.5 Hz Simor et al, (2013) Biol Psychol

  24. Correlations between NREM low alpha and REM high alpha NIGHTMARE SUBJECTS CONTROL SUBJECTS R = 0.22 P = 0.33 R = 0.78 P < 0.0001

  25. Correlation between nightmare severity and posterior EEG (O1,O2,Pz,P3,P4) activity in REM sleep in the nightmare group 9-13.5 Hz frequency frequency

  26. REM high alpha power peaked at posterior locations Wake-like EEG feature?

  27. 7.4 - 8.9 Hz 9.3 -10.9 Hz 11.3 -12.8 Hz Increased high alpha activity in NMs reflects a wake-like feature during REM sleep Cantero & Atienza, 2000

  28. Coexistence of sleep-like and wake like oscillatins in the human brain Nobili et al (2011)

  29. Terzano et al, (2000)

  30. Alpha band fluctuations and sleep disruption McKinney et al (2011)

  31. Descending - Ascending slopes • TRANSITION TO REM SLEEP • aminergic demodulation • cholinergic transmission • glutamate mediated amygdalar • activity • activation of brainstem and • fronto-limbic structures Phasic arousals, sleep disruption and wake-like oscillations Halász & Bódizs, 2013

  32. PRE vs. POST REM sleep periods

  33. PRE vs. POST REM sleep periods: alpha power * Condition (F(1,37) = 25.1; p < 0.00001) Group x Condition (F(1,37) = 9.84; p = 0.003) Increased alpha power in NMs only in pre-REM periods

  34. PRE vs. POST REM sleep periods: muscle tone Condition (F(1,36) = 9.26; p < 0.004) Group x Condition (F(1,36) = 2.77; p = 0.1) Tendency of increased muscle activity in NMs only in pre-REM periods

  35. Pre vs. Post REM: cardiovascular regulation * Group x Condition (F(1,37) = 7.89; p = 0.008) Decreased parasympathetic regulation in NM Significant group differences in pre-REM periods

  36. Summary • Behavioral studies: Impaired executive functions • Sleep macrostructure: impaired sleep continuity, frequent awakenings, reduced SWS, increaesed REM mediated by waking affect • Sleep microstructure: frequent arousals of mixed and high frequency components reflecting sleep instability • Spectral analyses: Wake-like alpha oscillations during REM sleep • Sleep disruption and wake-like oscillations appear in the transition to REM sleep (NREM-REM), but are not evident after the end of REM periods • Increased motor activity in pre-REM sleep, and reduced (state-independent) parasympathetic cardiovascular control

  37. Alerting mechanisms and mental activity: the intensification of dreaming • arousals, cortical activations and oneiric experience Conduit et al., 1997 Chelappa, 2011

  38. Sleep promotion vs. environmental monitoring OFF-LINE MODE ON-LINE MODE Marshall & Born, 2007

  39. Back to psychology and to the land of speculations • Arousals, wake-like oscillations – perceptually vivid, intense, real-like imagery, increased dream recall • Thin boundaries – absorption in dream images, fusion of dream and reality • Negative emotionality and inefficient emotional regulation – activation of fear-related memories, environmental threats • Alert non-restorative sleep

  40. Acknowledgements • Róbert Bódizs • Ferenc Gombos • Klára Horváth • János Körmendi • Ferri Raffaele • Péter P. Ujma • Klára Várhelyi This research was supported by the European Union and the State of Hungary, co-financed by the European Social Fund in the framework of TÁMOP 4.2.4. A/1-11-1-2012-0001 ‘National Excellence Program’.

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