Ruth O'Hara

Epidemiology of restless legs syndrome: A synthesis of the literature

Restless legs syndrome (RLS) has gained considerable attention in the recent years: nearly 50 community-based studies have been published in the last decade around the world. The development of strict diagnostic criteria in 1995 and their revision in 2003 helped to stimulate research interest on this syndrome. In community-based surveys, RLS has been studied as: 1) a symptom only, 2) a set of symptoms meeting minimal diagnostic criteria of the international restless legs syndrome study group (IRLSSG), 3) meeting minimal criteria accompanied with a specific frequency and/or severity, and 4) a differential diagnosis. In the first case, prevalence estimates in the general adult population ranged from 9.4% to 15%. In the second case, prevalence ranged from 3.9% to 14.3%. When frequency/severity is added, prevalence ranged from 2.2% to 7.9% and when differential diagnosis is applied prevalence estimates are between 1.9% and 4.6%. In all instances, RLS prevalence is higher in women than in men. It also increases with age in European and North American countries but not in Asian countries. Symptoms of anxiety and depression have been consistently associated with RLS. Overall, individuals with RLS have a poorer health than non-RLS but evidence for specific disease associations is mixed. Future epidemiological studies should focus on systematically adding frequency and severity in the definition of the syndrome in order to minimize the inclusion of cases mimicking RLS.

ASSESSING THE ACCURACY OF TOPOGRAPHIC EEG MAPPING FOR DETERMINING LOCAL BRAIN FUNCTION

OBJECTIVE There has been considerable discussion regarding the accuracy of topographic electroencephalographic (EEG) maps for assessing local cerebral function. We performed this study to test the accuracy of EEG mapping by examining the association between electrical activity and the perfusion under each electrode as another measure of local cerebral function. METHODS EEG mapping was performed simultaneously with (H15)2O positron emission tomography (PET) scanning in 6 normal adult subjects, both at rest and during a simple motor task. EEG data were processed using 3 different montages; two EEG power measures (absolute and relative power) were examined. RESULTS Relative power had much stronger associations with perfusion than did absolute power. In addition, calculating power for bipolar electrode pairs and averaging power over electrode pairs sharing a common electrode yielded stronger associations with perfusion than data from referential or single source montages. CONCLUSIONS These findings indicate (1) that topographic EEG mapping can accurately reflect local brain function in a way that is comparable to other methods, and (2) that the choice of EEG measure and montage have a significant influence on the degree with which maps reflect this local activity and function.

Categorical versus dimensional approaches to diagnosis: methodological challenges.

The arguments pitting categorical versus dimensional approaches to psychiatric diagnosis have been long ongoing with little sign of imminent resolution. We argue that categorical and dimensional approaches are fundamentally equivalent, but that one or other approach is more appropriate depending on the clinical circumstances and research questions being addressed. This paper aims to demonstrate (a) how these two approaches necessarily interdigitate, (b) to clarify the conditions under which one should utilize one approach over the other, and (c) to alert psychiatric clinicians and researchers to issues in the methodology literature that might facilitate their considerations. Using an example from the Infant Health and Development Program (IHDP), we illustrate the importance of using dimensional approaches for hypothesis testing, identify the problems with power and with interpretation that arise from employing a categorical approach, and underscore the importance of identifying the appropriate cutpoints when a categorical approach is necessitated. We argue that failure to utilize the correct approach under the appropriate circumstances can result in impaired clinical and research decision-making.

Variable effects of aging on frontal lobe contributions to memory.

Declarative memory declines with age, but there is profound variation in the severity of this decline. Healthy elderly adults with high or low memory scores and young adults viewed words under semantic or non-semantic encoding conditions while undergoing fMRI. Young adults had superior memory for the words, and elderly adults with high memory scores had better memory for the words than those with low memory scores. The elderly with high scores had left lateral and medial prefrontal activations for semantic encoding equal to the young, and greater right prefrontal activation than the young. The elderly with low scores had reduced activations in all three regions relative to the elderly with high memory scores. Thus, successful aging was characterized by preserved left prefrontal and enhanced right prefrontal activation that may have provided compensatory encoding resources.

Depression and Obstructive Sleep Apnea (OSA)

For over two decades clinical studies have been conducted which suggest the existence of a relationship between depression and Obstructive Sleep Apnea (OSA). Recently, Ohayon underscored the evidence for a link between these two disorders in the general population, showing that 800 out of 100,000 individuals had both, a breathing-related sleep disorder and a major depressive disorder, with up to 20% of the subjects presenting with one of these disorders also having the other. In some populations, depending on age, gender and other demographic and health characteristics, the prevalence of both disorders may be even higher: OSA may affect more than 50% of individuals over the age of 65, and significant depressive symptoms may be present in as many as 26% of a community-dwelling population of older adults.In clinical practice, the presence of depressive symptomatology is often considered in patients with OSA, and may be accounted for and followed-up when considering treatment approaches and response to treatment. On the other hand, sleep problems and specifically OSA are rarely assessed on a regular basis in patients with a depressive disorder. However, OSA might not only be associated with a depressive syndrome, but its presence may also be responsible for failure to respond to appropriate pharmacological treatment. Furthermore, an undiagnosed OSA might be exacerbated by adjunct treatments to antidepressant medications, such as benzodiazepines.Increased awareness of the relationship between depression and OSA might significantly improve diagnostic accuracy as well as treatment outcome for both disorders. In this review, we will summarize important findings in the current literature regarding the association between depression and OSA, and the possible mechanisms by which both disorders interact. Implications for clinical practice will be discussed.

Neuroanatomy of Fragile X Syndrome Is Associated with Aberrant Behavior and the Fragile X Mental Retardation Protein (FMRP)

To determine how neuroanatomic variation in children and adolescents with fragile X syndrome is linked to reduced levels of the fragile X mental retardation‐1 protein and to aberrant cognition and behavior.

Donepezil and flight simulator performance: Effects on retention of complex skills

Abstract—We report a randomized, double-blind, parallel group, placebo-controlled study to test the effects of the acetylcholinesterase inhibitor, donepezil (5 mg/d for 30 days), on aircraft pilot performance in 18 licensed pilots with mean age of 52 years. After 30 days of treatment, the donepezil group showed greater ability to retain the capacity to perform a set of complex simulator tasks than the placebo group, p < 0.05. Donepezil appears to have beneficial effects on retention of training on complex aviation tasks in nondemented older adults.

Relationship between brain electrical activity and cortical perfusion in normal subjects

Cerebral glucose uptake and perfusion are accepted as tightly coupled measures of energy utilization in both normal and diseased brain. The coupling of brain electrical activity to perfusion has been demonstrated, however, only in the presence of chronic brain disease. Very few studies have examined the relationship between cerebral electrical activity and energy utilization in normal brain tissue. To clarify this relationship, we performed 33 H2(15)O-positron emission tomography (PET) scans in six normal subjects both at rest and during a simple motor task, and acquired surface-recorded quantitative electroencephalogram (QEEG) data simultaneously with isotope injection. We examined the associations between cerebral perfusion directly underlying each recording electrode and three QEEG measures (absolute power, relative power, and cordance). All EEG measures had moderately strong coupling with perfusion at most frequency bands, although the directions of the associations differed from those previously reported in subjects with stroke or dementia. Of the three QEEG measures examined, cordance had the strongest relationship with perfusion (multiple R2 = 0.58). Cordance and PET were equally effective in detecting lateralized activation associated with the motor task, while EEG power did not detect this activation. Electrodes in the concordant state had a significantly higher mean perfusion than those in the discordant state. These results indicate that normal brain electrical activity has a moderately strong association with cerebral perfusion. Cordance may be the most useful QEEG measure for monitoring cerebral perfusion in subjects without chronic brain disease.

Late-Life Anxiety and Cognitive Impairment: A Review

Emerging research implicates a consistent reciprocal relationship between late-life anxiety and cognition. Understanding this relationship may clarify pathophysiological substrates of cognitive impairment and why co-occurring anxiety and cognitive impairment relates to poorer treatment prognosis for both conditions. This article critically reviews evidence of more prevalent anxiety in cognitively impaired older adults, elevated anxiety related to poorer cognitive performance, and more severe anxiety symptoms predicting future cognitive decline. It considers pathophysiologic mediators and moderators, and the influence of comorbid depression or medical illness in anxiety. Identified directions for future research includes use of in-depth anxiety assessment comparing normal and mild cognitively impaired older adults and use of challenging neuropsychological tests to determine if specific cognitive domains suffer in anxious older adults.

Serotonin Transporter Polymorphism, Memory, and Hippocampal Volume in the Elderly: Association and Interaction with Cortisol

The s allele variant of the serotonin transporter gene (5-HTT) has recently been observed to moderate the relationship of stress to depression and anxiety. To date no study has considered interactive effects of 5-HTT genotype, stress and hypothalamic–pituitary–adrenal (HPA) function on cognition in healthy, older adults, which may reflect developmental, functional or neurodegenerative effects of the serotonin transporter polymorphism. We investigated whether 5-HTT genotype interacts with cumulative life stress and HPA-axis measures of waking and diurnal cortisol slope to impact cognition in 154 non-depressed, older adults. Structural images of hippocampal volume were acquired on a subsample of 56 participants. The 5-HTT s allele was associated with both significantly lower delayed recall and higher waking cortisol levels. Presence of the s allele interacted with higher waking cortisol to negatively impact memory. We also observed a significant interaction of higher waking cortisol and the s allele on lower hippocampal volume. Smaller hippocampi and higher cortisol were associated with lower delayed recall only in s allele carriers. No impact or interactions of cumulative life stress with 5-HTT or cortisol were observed. This is the first investigation to identify an association of the 5-HTT s allele with poorer memory function in older adults. The interactive effects of the s allele and waking cortisol levels on reduced hippocampal volume and lower memory suggest that the negative effect of the serotonin polymorphism on memory is mediated by the HPA axis. Further, given the significant association of the s allele with higher waking cortisol in our investigation, future studies may be needed to evaluate the impact of the serotonin transporter polymorphism on any neuropsychiatric or behavioral outcome which is influenced by HPA axis function in older adults.