The contribution of fatigue and sleepiness to depression in patients attending the sleep laboratory for evaluation of obstructive sleep apnea

Purpose: A high prevalence of depressive symptomatology has been reported amongst sufferers of obstructive sleep apnea (OSA), but it remains unclear as to whether this is due to their OSA or other factors associated with the disorder. The current study aimed to assess the incidence and aetiology of depression in a community sample of individuals presenting to the sleep laboratory for diagnostic assessment of OSA. Methods: Forty-five consecutive individuals who presented to the sleep laboratory were recruited; of those, 34 were diagnosed with OSA, and 11 were primary snorers with no clinical or laboratory features of OSA. Nineteen control subjects were also recruited. Patients and controls completed the Beck Depression Inventory, the Profile of Mood States (POMS), and the Epworth Sleepiness Scale to assess their mood and sleepiness, prior to their polysomnography. Results: All patients reported significantly more depressive symptoms compared with healthy controls, regardless of their degree of OSA. There were no significant differences between OSA patients and primary snorers on any of the mood and self-rated sleepiness measures. Depression scores were not significantly associated with any of the nocturnal variables. Regression analysis revealed that the POMS fatigue subscale explained the majority of the variance in subjects' depression scores. Conclusions: Fatigue was the primary predictor of the level of depressive symptoms in patients who attended the sleep laboratory, regardless of the level of severity of sleep disordered breathing. When considering treatment options, practitioners should be aware of the concomitant occurrence of depressive symptoms and fatigue in patients presenting with sleep complaints, which may not be due to a sleep disorder

Characteristics of neutron emission profile from neutral beam heated plasmas of the Large Helical Device at various magnetic field strengths

The neutron emission profile of deuterium plasma in the Large Helical Device was measured with a multi-sightline vertical neutron camera under various magnetic field strength conditions. It was found that the line-integrated neutron emission profile shifts outward in the co-neutral beam (NB) case and inward in the counter NB case. Here, co- and counter directions correspond to enhance and reduce the poloidal magnetic field directions, respectively. The shift becomes more significant when the magnetic field decreased in strength. The experimentally obtained neutron emission profile was compared with the orbit-following models simulated through the DELTA5D code. The calculated neutron emission profiles vary according to the magnetic field strength because of the change of beam ion orbit and the slowing down due to the plasma parameter changes. Although a relatively narrow profile was obtained in the calculations at the inboard side for the co-NB case in the relatively low field condition, the profiles obtained through calculation and experiment were almost qualitatively aligned

The effect of 17-alpha hydroxyprogesterone caproate on the risk of gestational diabetes in singleton or twin pregnancies

To compare the rates of gestational diabetes (GDM) among women who received serial doses of 17 alpha hydroxyprogesterone caproate (17-OHPC) versus placebo

Sex differences in brain lateralization for clinically depressed patients

Research in neuropsychology has found depression to be related to impaired right hemisphere (RH) functioning. How clinical depression affects brain lateralized functioning for each sex, however, is not clear. The main aim of this thesis was to investigate how clinical depression impacts brain lateralized functioning for each sex. Additionally, this thesis investigates brain lateralization for emotional processing in a non-depressed group, as well as sex differences in brain lateralization for spatial, verbal, and emotional processing in a non-depressed group. In order to examine each of these research areas, sixty non-depressed participants, and thirty-nine dilnically depressed patients were recnjited to complete a set of neuropsychological tasks that measure brain lateralized spatial, verbal, and emotional functioning. The neuropsychological tasks that were selected also measure the brain regions known to be involved with depression (frontal lobe and right parietal lobe). The tasks were: the mental rotation task (MRT) to measure RH spatial functioning; the verbal fluency task (phonemic and semantic) to measure left hemisphere (LH) verbal functioning; and the chimeric faces task to measure frontal lobe emotional functioning. The data from these tasks were reported as two separate experiments. Experiment One examined sex differences in brain lateralization for spatial and verbal processing in a non-depressed group. Experiment One also investigates brain lateralization for emotional processing in a non-depressed group, in particular to determine whether there is a sex difference in brain lateralization for emotional processing. The aim of Experiment One was to replicate the male advantage in spatial processing and the female advantage in verbal processing, which have previously been interpreted as reflecting sex differences in brain lateralization for these functions. It was also the aim to differentiate between the competing RH and valence hypotheses of brain lateralization for emotional processing and further investigate sex differences in brain lateralization for emotional processing. Sex differences in brain lateralization for spatial, verbal, and emotional processing were examined by comparing the performance of thirty non-depressed males and thirty non-depressed females on the MRT, verbal fluency task, and chimeric faces task respectively. The hypothesis that males would mentally rotate the stimuli of the MRT faster than the females was not supported, as no significant sex differences in performance were observed on the MRT. Failure to replicate the male advantage in spatial functioning was attributed to a possible sex difference in level of spatial ability, which has been found to mediate hemispheric functioning. The hypothesis that the females would generate significantly more words than the males on the verbal fluency task was supported, thus replicating the female advantage in verbal processing. For the chimeric faces task, the group findings supported the RH hypothesis for brain lateralization for emotional processing, with responses being significanfly faster and more accurate to happy and sad expressions shown in the LVF than in the RVF. No consistent sex differences in performance were observed between the RT and accuracy rate analyses of the chimeric faces task. Reaction times to the chimeric faces showed a LVF advantage in emotional processing for the males, and no hemispheric bias for emotional processing for the females. In contrast, recognition accuracy of the chimeric faces showed a LVF advantage for emotional processing for both the males and the females. The inconsistent sex differences on the chimeric faces task suggests that there is not a strong sex difference in brain lateralization for emotional processing. Expertment Two investigated brain lateralization for spatial, verbal, and emotional functioning in a clinically depressed group. It was the aim of Experiment Two to determine whether clinical depression is associated with impaired RH functioning, as suggested by the literature. It was also the aim of Experiment Two to examine more specifically, how clinical depression affects brain lateralized functioning for each sex separately. To examine the effect of clinical depression on brain lateralized functioning, the performance of thirty-six (fifteen males, twenty-one females) clinically depressed patients (three excluded from the recruited thirty-nine) and thirty-six (eighteen males, eighteen females) non-depressed control participants was compared on the MRT, verbal fluency task, and chimeric faces task. The hypothesis that clinical depression would be associated with impaired RH functioning was partially supported by the results of Experiment Two. The depressed group performed signiflcantiy poorer than the control group on both the RH task (the MRT intercept and overall R and the LH task (semantic verbal fluency). Therefore, impaired RH and LH functioning on the spatial and verbal task was evidenced for the clinically depressed group in Experiment Two. A RH impairment in emotional functioning with clinical depression could not be clearly ascertained from the results of the chimeric faces task. The RT analyses of the chimeric faces task showed a LVF advantage for emotional processing for both the control and depressed groups. In contrast to the RT analyses, the accuracy rate analyses of the chimeric faces task showed a LVF advantage in emotional processing for the control group, and no hemispheric bias for emotional processing for the depressed group, As the depressed group were significantly impaired for both RH and LH functioning in Experiment Two, it is possible that the findings of Experiment Two are reflective of a generalised performance deficit associated with clinical depression, rather than to a disturbance in brain lateralized functioning. The depressed group was also found to respond significantly slower than the control group in overall RT on the MRT and chimeric faces task. The significant group difference on the intercept of the FART implicates impaired information encoding for the clinically depressed group. The slowed Ris of the depressed group may also reflect impaired pre-motor organization with clinical depression, thus resulting in delayed motor responses. In relation to the affect of clinical depression on brain lateralizaflon for each sex, it was hypothesised that the depressed males would perform significantly poorer than the depressed females on tasks measuring functions lateralized to the cerebral hemisphere impaired due to clinical depression. The premise for this hypothesis lies in the evidence from past unilateral brain lesion research, which suggests that the stronger brain ateralization of males restricts assistance from the unimpaired hemisphere to perform the task of the impalred hemisphere. The bilateralization of females however, allows greater assistance of the unimpaired hemisphere to perform the task at hand. In contrast to the hypothesis however, there was no evidence from the results of Experiment Two that clinical depression had a greater impact on the brain lateralized functioning of males than females. No significant sex differences in performance on the FART were observed for either the non-depressed control group or clinical depressed group. For the verbal fluency task, a female advantage in word generation was observed for both phonemic and semantic fluency, regardless of group. Also regardless of group, the RT analyses of the chimeric faces task showed that the males responded significantly faster to emotional expressions shown in the LVF than in the RVF. For the females however, there was no hemispheric bias in RT for emotional processing. The accuracy rate analyses from the chimeric faces task also showed no sex differences for either group. The similar findings of sex differences between the control and depressed groups across each task suggests that clinical depression had a similar impact on both the males and the females, regardless of brain late ralization. The results of Experiment Two could be indicative of impaired LH and RH functioning with clinical depression, or of a generalised performance deficit with clinical depression. A generalised performance deficit for the clinically depressed group in Experiment Two may explain why a sex difference in the effects of clinical depression on brain lateralized functioning was not observed. Future research observing a RH impairment with clinical depression is encouraged to further examine the affect of clinical depression on brain lateralization for each sex separately. Further understanding of the affect of clinical depression on brain lateralization for each sex could provide addiional information on sex difference in the prevalence of clinical depression

The effects of electro-convulsive therapy on the speed of information processing in major depression

This study investigates whether cognitive impairment is evident in inpatients diagnosed with Major Depression (MD) following electro-convulsive therapy (ECT), and if so, whether it is independent from depressive symptomatology. Speed of information processing was measured using the inspection time (IT) task. IT was compared between twelve inpatients diagnosed with MD receiving ECT and twelve age-, gender-, verbal IQ-, and depression and anxiety severity matched control inpatients diagnosed with MD not receiving ECT, over four testing sessions (prior to ECT, following one ECT session, following the completion of an ECT block, and 4 to 6 weeks after the ECT block (follow-up)). The mean IT score for the inpatients diagnosed with MD who received ECT slowed significantly from the first ECT to immediately after the ECT block, and was significantly faster at follow-up. The mean IT score of the inpatients diagnosed with MD not receiving ECT gradually but significantly became faster over the entire equivalent time period. Small sample sizes were a limitation. ECT temporarily slows information processing speed in MD patients, independent of depression symptomatology

Sleep disruption in Quadriplegia - exploring whether 3mg melatonin induces sleep

Previous research has shown that people with complete cervical spinal cord injury (quadriplegia) commonly report sleep disturbances, have delayed REM latency and lack endogenous melatonin production. It is unclear if these findings are related. The aim of this study was to investigate whether nightly supplementation of 3 mg melatonin would induce, shift the phase of and/or modify subjective sleep for people with complete quadriplegia

Neuropsychological sequelae of digital mobile phone exposure in humans

The effect of electromagnetic fields from digital mobile phones (DMP) on cognitive functioning is an area receiving increased attention. This study compares the performance of 120 volunteers on 8 neuropsychological tests during real or sham exposure to a DMP set to maximum permissible radiofrequency power output. When results were adjusted for known covariates (gender, age, or education), several alterations at significance levels of p < 0.05 were obtained. Of these, simple and choice reaction times (CRT) showed strong evidence of impairment. Further, performance on the Trail Making Task (TMT) improved, supporting the hypothesis that DMP radiofrequency emissions improve the speed of processing of information held in working memory

The sensitivity of human event-related potentials and reaction time to mobile phone emitted electromagnetic fields

There is some evidence to suggest that exposure to mobile phones (MPs) can affect neural activity, particularly in response to auditory stimuli. The current investigation (n = 120) aimed to test recent findings in this area, namely that N100 amplitude and latency would decrease, and that P300 latency and reaction time (RT) would increase under active relative to sham exposure during an auditory task. Visual measures were also explored. A double blind, counterbalanced, crossover design was employed where subjects attended two sessions 1 week apart. In both sessions participants (1) performed auditory and visual oddball tasks while electroencephalogram (EEG) was recorded with a MP set to sham exposure mounted over the temporal region, and (2) performed the same tasks while the handset was set to active/sham. When active, the MP transmitted for 30 min at 895 MHz (average power 250 mW, pulse modulated at 217 Hz, average SAR 0.11 W/kg). Paired t-tests compared difference scores from the sham/sham session to those from the sham/active condition. The study was designed to detect differences of 1/4 of a standard deviation with a power of 0.80. There was no significant difference between exposure conditions for any auditory or visual event related potential (ERP) component or RT. As previous positive findings were not replicated, it was concluded that there is currently no evidence that acute MP exposure affects these indices of brain activity

Melatonin supplementation in patients with complete tetraplegia and poor sleep

People with complete tetraplegia have interrupted melatonin production and commonly report poor sleep. Whether the two are related is unclear. This pilot study investigated whether nightly supplementation of 3 mg melatonin would improve objective and subjective sleep in tetraplegia. Five participants with motor and sensory complete tetraplegia ingested 3 mg melatonin (capsule) two hours prior to usual sleep time for two weeks. Full portable sleep studies were conducted in participants' homes on the night before commencing melatonin supplementation (baseline) and on the last night of the supplementation period. Endogenous melatonin levels were determined by assaying saliva samples collected the night of (just prior to sleep) and morning after (upon awakening) each sleep study. Prior to each sleep study measures of state sleepiness and sleep behaviour were collected. The results showed that 3 mg of melatonin increased salivary melatonin from near zero levels at baseline in all but one participant. A delay in time to Rapid Eye Movement sleep, and an increase in stage 2 sleep were observed along with improved subjective sleep experience with a reduction in time to fall asleep, improved quality of sleep and fewer awakenings during the night reported. Daytime sleepiness increased however. A randomised, placebo controlled trial with a larger sample is required to further explore and confirm these findings