Nozomu Kotorii

Sleep Findings in Young Adult Patients with Posttraumatic Stress Disorder

BACKGROUND Laboratory sleep studies in posttraumatic stress disorder (PTSD) have not provided consistent evidence of sleep disturbance, despite apparent sleep complaints. Most of these studies have investigated middle-aged chronic PTSD subjects with a high prevalence of comorbidities such as substance dependence and/or personality disorder. METHODS Ten young adult PTSD patients (aged 23.4 +/- 6.1 years) without comorbidities of substance dependence and/or personality disorder underwent 2-night polysomnographic recordings. These sleep measures were compared with those of normal control subjects and were correlated with PTSD symptoms. RESULTS Posttraumatic stress disorder patients demonstrated significantly poorer sleep, reduced sleep efficiency caused by increased wake time after sleep onset, and increased awakening from rapid eye movement (REM) sleep (REM interruption). We found significant positive correlations between the severity of trauma-related nightmare complaints and the percentage of REM interruption, as well as wake time after sleep onset. CONCLUSIONS The results indicate that trauma-related nightmares are an important factor resulting in increased REM interruptions and wake time after sleep onset in PTSD.

HYPOCRETIN/OREXIN AND NARCOLEPSY NEW BASIC AND CLINICAL INSIGHTS

Narcolepsy is a chronic sleep disorder, characterized by excessive daytime sleepiness (EDS), cataplexy, sleep paralysis and hypnagogic hallucinations. Both sporadic (95%) and familial (5%) forms of narcolepsy exist in humans. The major pathophysiology of human narcolepsy has been recently discovered based on the discovery of narcolepsy genes in animals; the genes involved in the pathology of the hypocretin/orexin ligand and its receptor. Mutations in hypocretin‐related genes are rare in humans, but hypocretin ligand deficiency is found in a large majority of narcolepsy with cataplexy. Hypocretin ligand deficiency in human narcolepsy is probably due to the post‐natal cell death of hypocretin neurones. Although a close association between human leucocyte antigen (HLA) and human narcolepsy with cataplexy suggests an involvement of autoimmune mechanisms, this has not yet been proved. Hypocretin deficiency is also found in symptomatic cases of narcolepsy and EDS with various neurological conditions, including immune‐mediated neurological disorders, such as Guillain–Barre syndrome, MA2‐positive paraneoplastic syndrome and neuromyelitis optica (NMO)‐related disorder. The findings in symptomatic narcoleptic cases may have significant clinical relevance to the understanding of the mechanisms of hypocretin cell death and choice of treatment option. The discoveries in human cases lead to the establishment of the new diagnostic test of narcolepsy (i.e. low cerebrospinal fluid hypocretin‐1 levels for ‘narcolepsy with cataplexy’ and ‘narcolepsy due to medical condition’). As a large majority of human narcolepsy patients are ligand deficient, hypocretin replacement therapy may be a promising new therapeutic option, and animal experiments using gene therapy and cell transplantations are in progress.

Effect of zolpidem on sleep architecture and its next-morning residual effect in insomniac patients: a randomized crossover comparative study with brotizolam.

This study was conducted to determine the effect of zolpidem (ZOL) 10 mg orally on the sleep architecture and the next-morning residual effect in patients with non-organic insomnia (ICD-10) as compared to the effect of brotizolam (BTM) 0.25 mg orally, a widely used short-acting benzodiazepine (BZD) hypnotic in Japan, in a randomized, crossover comparative study. Fourteen patients with non-organic insomnia (3 males and 11 females; mean age of 54.9+/-S.D. 8.9 years). First three nights with placebo, middle three nights with either ZOL 10 mg or BTM 0.25 mg, and last three nights again with placebo in each session (a total of two sessions). Primary endpoints were polysomnography findings of sleep stages, sleep parameters, and sleep latency (SL) in the morning to examine calculable sleepiness as a residual effect. Secondary endpoint was sleep quality assessed by self-assessment questionnaire. At 150 min after Tmax, both ZOL and BTM significantly increased stage 2 (S2), and ZOL showed significantly longer slow wave sleep (SWS; stage 3+4) as compared to BTM. Stage wake was significantly increased by ZOL at the first withdrawal night and by BTM at the second withdrawal night. ZOL did not affect SL after rising, whereas BTM showed significantly shorter SL. Both drugs reduced the number of nocturnal awakenings and improved subjective sleep quality. The common adverse drug reaction (ADR) was sleepiness (3 patients) in each treatment. All events were mild. No serious adverse events occurred. ZOL is as effective as BTM in improving subjective sleep quality in patients with psychophysiological insomnia (PPI). ZOL has advantages over BTM in having a unique profile of increasing SWS with less next-morning residual effect.

New susceptibility variants to narcolepsy identified in HLA class II region

Narcolepsy, a sleep disorder characterized by excessive daytime sleepiness, cataplexy and rapid eye movement sleep abnormalities, is tightly associated with human leukocyte antigen HLA-DQB1*06:02. DQB1*06:02 is common in the general population (10-30%); therefore, additional genetic factors are needed for the development of narcolepsy. In the present study, HLA-DQB1 in 664 Japanese narcoleptic subjects and 3131 Japanese control subjects was examined to determine whether HLA-DQB1 alleles located in trans of DQB1*06:02 are associated with narcolepsy. The strongest association was with DQB1*06:01 (P = 1.4 × 10(-10), odds ratio, OR = 0.39), as reported in previous studies. Additional predisposing effects of DQB1*03:02 were also found (P = 2.5 × 10(-9), OR = 1.97). A comparison between DQB1*06:02 heterozygous cases and controls revealed dominant protective effects of DQB1*06:01 and DQB1*05:01. In addition, a single-nucleotide polymorphism-based conditional analysis controlling for the effect of HLA-DQB1 was performed to determine whether there were other independent HLA associations outside of HLA-DQB1. This analysis revealed associations at HLA-DPB1 in the HLA class II region (rs3117242, P = 4.1 × 10(-5), OR = 2.45; DPB1*05:01, P = 8.1 × 10(-3), OR = 1.39). These results indicate that complex HLA class II associations contribute to the genetic predisposition to narcolepsy.

A polymorphism in CCR1/CCR3 is associated with narcolepsy.

Etiology of narcolepsy-cataplexy involves multiple genetic and environmental factors. While the human leukocyte antigen (HLA)-DRB1*15:01-DQB1*06:02 haplotype is strongly associated with narcolepsy, it is not sufficient for disease development. To identify additional, non-HLA susceptibility genes, we conducted a genome-wide association study (GWAS) using Japanese samples. An initial sample set comprising 409 cases and 1562 controls was used for the GWAS of 525,196 single nucleotide polymorphisms (SNPs) located outside the HLA region. An independent sample set comprising 240 cases and 869 controls was then genotyped at 37 SNPs identified in the GWAS. We found that narcolepsy was associated with a SNP in the promoter region of chemokine (C-C motif) receptor 1 (CCR1) (rs3181077, P=1.6×10(-5), odds ratio [OR]=1.86). This rs3181077 association was replicated with the independent sample set (P=0.032, OR=1.36). We measured mRNA levels of candidate genes in peripheral blood samples of 38 cases and 37 controls. CCR1 and CCR3 mRNA levels were significantly lower in patients than in healthy controls, and CCR1 mRNA levels were associated with rs3181077 genotypes. In vitro chemotaxis assays were also performed to measure monocyte migration. We observed that monocytes from carriers of the rs3181077 risk allele had lower migration indices with a CCR1 ligand. CCR1 and CCR3 are newly discovered susceptibility genes for narcolepsy. These results highlight the potential role of CCR genes in narcolepsy and support the hypothesis that patients with narcolepsy have impaired immune function.

Overview of Management of Narcolepsy

Narcolepsy is a chronic sleep disorder that is characterized by excessive daytime sleepiness, cataplexy, hypnagogic hallucinations, and sleep paralysis. Since these symptoms are often disabling, most patients need lifelong treatments. Non-pharmacological treatments (i.e., behavioral modification) are often helpful for the clinical management of narcoleptic patients. However, over 90% of diagnosed narcoleptic patients are reported to take medications to control their symptoms. Traditionally, the amphetamine-like CNS stimulants have been used for clinical management to improve EDS, and trycyclic antidepressants as anticataplectics, but the treatment has evolved recently with new and better-tolerated compounds such as modafinil (and its r-enantiomer, armodafinil) for EDS and adrenergic/serotonergic selective reuptake inhibitors as anticataplectics. Nighttime administration of a short-acting sedative, gamma-hydroxybutyrate (sodium oxybate in the USA) has also been used for the treatment for EDS and cataplexy. Since a large majority of human narcolepsy patients are hypocretin peptide-deficient, hypocretin replacement therapy may also be a new therapeutic option, but this is still not available for human patients. If hypocretin replacement is effective in hypocretin-deficient narcolepsy, cell transplantation and/or gene therapy may be developed in the near future. In this review, we first describe clinical symptoms of narcolepsy, and then the state-of-the-art knowledge about both pharmacological and non-pharmacological treatments of narcolepsy.

An association analysis of HLA-DQB1 with narcolepsy without cataplexy and idiopathic hypersomnia with/without long sleep time in a Japanese population

Narcolepsy without cataplexy (NA w/o CA) (narcolepsy type 2) is a lifelong disorder characterized by excessive daytime sleepiness and rapid eye movement (REM) sleep abnormalities, but no cataplexy. In the present study, we examined the human leukocyte antigen HLA-DQB1 in 160 Japanese patients with NA w/o CA and 1,418 control subjects. Frequencies of DQB1*06:02 were significantly higher in patients with NA w/o CA compared with controls (allele frequency: 16.6 vs. 7.8%, P=1.1×10−7, odds ratio (OR)=2.36; carrier frequency: 31.3 vs. 14.7%, P=7.6×10−8, OR=2.64). Distributions of HLA-DQB1 alleles other than DQB1*06:02 were compared between NA w/o CA and narcolepsy with cataplexy (NA-CA) to assess whether the genetic backgrounds of the two diseases have similarities. The distribution of the HLA-DQB1 alleles in DQB1*06:02-negative NA w/o CA was significantly different from that in NA-CA (P=5.8×10−7). On the other hand, the patterns of the HLA-DQB1 alleles were similar between DQB1*06:02-positive NA w/o CA and NA-CA. HLA-DQB1 analysis was also performed in 186 Japanese patients with idiopathic hypersomnia (IHS) with/without long sleep time, but no significant associations were observed.

A variant at 9q34.11 is associated with HLA-DQB1*06:02 negative essential hypersomnia

Essential hypersomnia (EHS) is a lifelong disorder characterized by excessive daytime sleepiness without cataplexy. EHS is associated with human leukocyte antigen (HLA)-DQB1*06:02, similar to narcolepsy with cataplexy (narcolepsy). Previous studies suggest that DQB1*06:02-positive and -negative EHS are different in terms of their clinical features and follow different pathological pathways. DQB1*06:02-positive EHS and narcolepsy share the same susceptibility genes. In the present study, we report a genome-wide association study with replication for DQB1*06:02-negative EHS (408 patients and 2247 healthy controls, all Japanese). One single-nucleotide polymorphism, rs10988217, which is located 15-kb upstream of carnitine O-acetyltransferase (CRAT), was significantly associated with DQB1*06:02-negative EHS (P = 7.5 × 10−9, odds ratio = 2.63). The risk allele of the disease-associated SNP was correlated with higher expression levels of CRAT in various tissues and cell types, including brain tissue. In addition, the risk allele was associated with levels of succinylcarnitine (P = 1.4 × 10−18) in human blood. The leading SNP in this region was the same in associations with both DQB1*06:02-negative EHS and succinylcarnitine levels. The results suggest that DQB1*06:02-negative EHS may be associated with an underlying dysfunction in energy metabolic pathways.

Chronic Powder Diet After Weaning Induces Sleep, Behavioral, Neuroanatomical, and Neurophysiological Changes in Mice

The purpose of this study is to clarify the effects of chronic powder diet feeding on sleep patterns and other physiological/anatomical changes in mice. C57BL/6 male mice were divided into two groups from weaning: a group fed with solid food (SD) and a group fed with powder food (PD), and sleep and physiological and anatomical changes were compared between the groups. PD exhibited less cranial bone structure development and a significant weight gain. Furthermore, these PD mice showed reduced number of neurogenesis in the hippocampus. Sleep analysis showed that PD induced attenuated diurnal sleep/wake rhythm, characterized by increased sleep during active period and decreased sleep during rest period. With food deprivation (FD), PD showed less enhancement of wake/locomotor activity compared to SD, indicating reduced food-seeking behavior during FD. These results suggest that powder feeding in mice results in a cluster of detrimental symptoms caused by abnormal energy metabolism and anatomical/neurological changes.

S21-4. Neuropathological hypothesis of sleep dysfunction in Schizophrenia

The purpose of this lecture is to review the polysomnographic non-rapid eye movement sleep abnormalities in schizophrenic patients and to present evidence for possible pathophysiologic mechanisms. Deficits of delta wave sleep are commonly reported sleep architecture abnormalities in schizophrenia. In the1960’s, Feinberg described this abnormality and about twenty years later, he first proposed that a decline in synaptic density resulting from abnormal reorganization of brain structure during early adolescence might cause the decline in delta wave amplitude and the onset of schizophrenia. Recent neuropathological studies of schizophrenia revealed that the dendritic spine density was particularly reduced in layer three of the neocortex. And excessive spine pruning is now considered a potential factor underlying reduced cortical gray matter volume in schizophrenia. Aberrant neuronal pruning is also believed to contribute to compromise the thalamocortical circuitry. Several recent studies have reported markedly reduced sleep spindle activity mediated by thalamocortical circuits in schizophrenia. Animal studies have reported sleep spindles have been linked to synaptic plasticity and memory consolidation. Thus, aberrant pruning can result in structural brain abnormalities and deficits of two distinct rhythms during sleep. Furthermore, each of these impairments appears to be associated with both cognitive deficits and symptoms of schizophrenia.