Liat Ayalon

Cognitive Effects of Treating Obstructive Sleep Apnea in Alzheimer's Disease: A Randomized Controlled Study

OBJECTIVES: To examine whether treatment of obstructive sleep apnea (OSA) with continuous positive airway pressure (CPAP) in patients with Alzheimers disease (AD) results in better cognitive function.

Traumatic Brain Injury and Sleep Disturbance: A Review of Current Research

ObjectiveTo summarize the current literature regarding the significant prevalence and potential consequences of sleep disturbance following traumatic brain injury (TBI), particularly mild TBI. DesignPubMed and Ovid/MEDLINE databases were searched by using key words “sleep disturbance,” “insomnia,” “TBI,” “brain injury,” and “circadian rhythms.” Additional sources (eg, abstracts from the annual Associated Professional Sleep Societies meeting) were also reviewed. ResultsSequelae of TBI include both medical and psychiatric symptoms and frequent complaints of sleep disturbance. Sleep disturbance likely result from and contribute to multiple factors associated with the injury, all of which complicate recovery and resolution of symptoms. Interestingly, research now seems to indicate that mild TBI may be more correlated with increased likelihood of sleep disturbance than are severe forms of TBI. ConclusionsSleep disturbance is a common consequence of TBI, but much more research is required to elucidate the nature and extent of this relation. Research needs to focus on (1) uncovering the specific types, causes, and severity of TBI that most often lead to sleep problems; (2) the specific consequences of sleep disturbance in this population (eg, impaired physical or cognitive recovery); and (3) the most effective strategies for the treatment of sleep-wake abnormalities in this population.

Circadian rhythm sleep disorders following mild traumatic brain injury

Objective: To describe the physiologic and behavioral characteristics of circadian rhythm sleep disorders (CRSDs) following minor traumatic brain injury (mTBI) in patients complaining of insomnia. Methods: Forty two patients with insomnia complaints following mTBI were screened. Those suspected of having CRSD underwent actigraphy, saliva melatonin and oral temperature measurement, and polysomnography. All patients also filled out a self-reported questionnaire to determine their circadian preference. Results: Fifteen of the 42 patients (36%) with complaints of insomnia following mTBI were diagnosed with CRSD. Eight patients displayed a delayed sleep phase syndrome (DSPS), whereas seven displayed an irregular sleep–wake pattern (ISWP). Whereas all patients with DSPS exhibited a 24-hour periodicity of oral temperature rhythm, three of seven patients with ISWP lacked such a daily rhythm. In addition, ISWP patients exhibited smaller amplitude of oral temperature rhythm vs the DSPS group. Subjective Morningness–Eveningness Questionnaire scores were in accordance with the clinical diagnosis of DSPS or ISWP based on actigraphy. Conclusions: Minor traumatic brain injury might contribute to the emergence of circadian rhythm sleep disorders. Two types of these disorders were observed: delayed sleep phase syndrome and irregular sleep–wake pattern. The types differed in the subjective questionnaire scores and had distinct profiles of melatonin and temperature circadian rhythms.

Sleep in the Elderly: Normal Variations and Common Sleep Disorders

The most common complaints of older adults concern their difficulty initiating or maintaining sleep, which results in insufficient sleep and an increased risk of falls, difficulty with concentration and memory, and overall decreased quality of life. Difficulties sleeping are not, however, an inevitable part of aging. Rather, the sleep complaints are often comorbid with medical and psychiatric illness, associated with the medications used to treat those illnesses, or the result of circadian rhythm changes or other sleep disorders. Health care professionals specializing in geriatrics need to learn to recognize the different causes of sleep disturbances in this population and to initiate appropriate treatment. Nonpharmacological treatment techniques are discussed; pharmacological treatments are discussed in a companion article.

Continuous positive airway pressure reduces subjective daytime sleepiness in patients with mild to moderate alzheimer's disease with sleep disordered breathing

OBJECTIVES: Studies have reported that 33% to 70% of patients with Alzheimers disease (AD) have sleep‐disordered breathing (SDB). Continuous positive airway pressure (CPAP) treatment has been shown to reduce daytime sleepiness and improve health‐related quality of life in nondemented older people with SDB. The effect of therapeutic CPAP treatment on daytime sleepiness in patients with mild‐moderate AD with SDB was assessed.

Increased brain activation during verbal learning in obstructive sleep apnea

This study examined the cerebral response to a verbal learning (VL) task in obstructive sleep apnea (OSA) patients. Twelve OSA patients and 12 controls were studied with functional magnetic resonance imaging (FMRI). As hypothesized, VL performance was similar for both groups, but OSA patients showed increased brain activation in several brain regions. These regions included bilateral inferior frontal and middle frontal gyri, cingulate gyrus, areas at the junction of the inferior parietal and superior temporal lobes, thalamus, and cerebellum. Better free recall performance in the OSA group was related to increased cerebral responses within the left inferior frontal gyrus and left supramarginal area. Recall was negatively related to activation within the left inferior parietal lobe. The findings support the predictions that intact performance in OSA patients is associated with increased cerebral response. Recruitment of additional brain regions to participate in VL performance in OSA patients likely represents an adaptive compensatory recruitment response, similar to that observed in young adults following total sleep deprivation and in healthy older adults. These data, and those of the only other FMRI study in OSA, suggest that individuals with OSA show characteristic differences in the BOLD signal response to cognitive challenges. Including subjects with untreated OSA in neuroimaging studies may potentially influence the results by altering individual and group level activation patterns. Given this, future neuroimaging studies may want to be aware of this potential confound.

Obstructive Sleep Apnea and Age A Double Insult to Brain Function

RATIONALE Healthy aging is associated with cognitive deficits similar to those found in obstructive sleep apnea (OSA). As in OSA, older adults show compensatory cerebral activation during cognitive demands in the face of neurocognitive decline. OBJECTIVES The current study examines whether the combination of increasing age and sleep apnea will lead to a stronger compensatory response than either factor alone, or overwhelm the brains capacity to compensate. METHODS A total of 14 treatment-naive patients with sleep apnea (aged 25-59 yr) and 14 age-matched healthy control subjects were each divided into two age groups of young (<45 yr) and middle-aged (> or = 45 yr). All underwent a sleep study, followed the next morning by a functional magnetic resonance imaging session that included a sustained attention and a verbal encoding task. A priori contrast analyses compared middle-aged patients with OSA to young patients, young control subjects, and middle-aged control subjects. MEASUREMENTS AND MAIN RESULTS Middle-aged patients with OSA showed reduced performance for immediate word recall and slower reaction time during sustained attention compared with the other three groups (middle-aged control, young sleep apnea, and young control). For both tasks, decreased activation was detected for middle-aged sleep apnea relative to the other groups in task-related brain regions. CONCLUSIONS These results suggest that the presence of both sleep apnea and increasing age overwhelmed the brains capacity to respond to cognitive challenges with compensatory recruitment and to maintain performance. The findings that sleep apnea impairs performance and brain function at a younger age than what might ordinarily be expected underscore the importance of early diagnosis and treatment of sleep apnea.

An arterial spin labeling investigation of cerebral blood flow deficits in chronic stroke survivors.

Although the acute stroke literature indicates that cerebral blood flow (CBF) may commonly be disordered in stroke survivors, limited research has investigated whether CBF remains aberrant in the chronic phase of stroke. A directed study of CBF in stroke is needed because reduced CBF (hypoperfusion) may occur in neural regions that appear anatomically intact and may impact cognitive functioning in stroke survivors. Hypoperfusion in neurologically-involved individuals may also affect BOLD signal in FMRI studies, complicating its interpretation with this population. The current study measured CBF in three chronic stroke survivors with ischemic infarcts (greater than 1 year post-stroke) to localize regions of hypoperfusion, and most critically, examine the CBF inflow curve using a methodology that has never, to our knowledge, been reported in the chronic stroke literature. CBF data acquired with a Pulsed Arterial Spin Labeling (PASL) flow-sensitive alternating inversion recovery (FAIR) technique indicated both delayed CBF inflow curve and hypoperfusion in the stroke survivors as compared to younger and elderly control participants. Among the stroke survivors, we observed regional hypoperfusion in apparently anatomically intact neural regions that are involved in cognitive functioning. These results may have profound implications for the study of behavioral deficits in chronic stroke, and particularly for studies using neuroimaging methods that rely on CBF to draw conclusions about underlying neural activity.

Altered brain activation during response inhibition in obstructive sleep apnea

This study examined response inhibition during a Go–NoGo task in individuals with obstructive sleep apnea (OSA). Fourteen OSA patients and 14 controls were studied with functional magnetic resonance imaging. Compared to controls, the OSA group showed more false positives (error of commission) during the NoGo trials with decreased brain activation in the left postcentral gyrus, cingulate gyrus and inferior parietal lobe, as well as right insula and putamen. This is consistent with previous findings of impaired performance and decreased brain activation in OSA patients during a working memory task, suggesting that compromised brain function in response to cognitive challenges may underlie some of the cognitive deficits seen in patients with OSA.

Electrolytic lesion of globus pallidus ameliorates the behavioral and neurodegenerative effects of quinolinic acid lesion of the striatum: a potential novel treatment in a rat model of Huntington's disease

Bilateral electrolytic pallidal lesion ameliorated the deleterious effects of bilateral quinolinic acid (QA) lesion to the striatum on post-surgery weight, activity level, and performance in a water maze task, and reduced the extent of striatal damage. Given that the neurodegenerative and behavioral effects of QA striatal lesion are thought to mimic those seen in Huntingtons disease, these results may point to a potential novel treatment for this disease.