Romola S. Bucks

Neurocognitive function in obstructive sleep apnoea: A meta-review

Adult obstructive sleep apnoea (OSA) is associated with cognitive dysfunction. While many review articles have attempted to summarize the evidence for this association, it remains difficult to determine which domains of cognition are affected by OSA. This is because of marked differences in the nature of these reviews (e.g. many are unsystematic) and the many different tasks and domains assessed. This paper addresses this issue by comparing the results of only systematic reviews or meta‐analyses assessing the effects of OSA on cognition, the relationship between OSA severity and cognition, and/or the effects of treatment on cognition in OSA. Electronic databases and hand‐searching were undertaken to select reviews that reported on these areas. We found 33 reviews; five reviews met predetermined, stringent selection criteria. The majority of reviews supported deficits in attention/vigilance, delayed long‐term visual and verbal memory, visuospatial/constructional abilities, and executive function in individuals with OSA. There is also general agreement that language ability and psychomotor function are unaffected by OSA. Data are equivocal for the effects of OSA on working memory, short‐term memory and global cognitive functioning. Attention/vigilance dysfunction appears to be associated with sleep fragmentation and global cognitive function with hypoxaemia. Continuous positive airway pressure treatment of OSA appears to improve executive dysfunction, delayed long‐term verbal and visual memory, attention/vigilance and global cognitive functioning. In order to improve our understanding of cognitive dysfunction in OSA, future research should pay particular attention to participant characteristics, measures of disease severity and choice of neuropsychological tests.

Exercise and Parkinson's: benefits for cognition and quality of life

Cruise KE, Bucks RS, Loftus AM, Newton RU, Pegoraro R, Thomas MG. Exercise and Parkinson’s: benefits for cognition and quality of life.
Acta Neurol Scand: 2011: 123: 13–19.
© 2010 The Authors Journal compilation

Adherence to Treatment in Adolescents with Cystic Fibrosis: The Role of Illness Perceptions and Treatment Beliefs

OBJECTIVES This study was conducted to explore the relationships between illness perceptions, emotional representations, treatment beliefs and reported adherence in adolescents with cystic fibrosis (CF). METHODS Thirty-eight adolescents completed questionnaires assessing their perceptions of CF, beliefs about prescribed treatments and reported adherence to chest physiotherapy, enzyme supplements, and antibiotics. RESULTS Reported non-adherence to chest physiotherapy was associated with the way in which patients judged their personal need for treatment relative to their concerns about potential adverse effects. Patients reported strong doubts about the necessity of chest physiotherapy. Reported non-adherence to antibiotics was related to doubts about the necessity of antibiotics, believing that CF is not amenable to treatment control. Despite these beliefs about treatment, participants perceived CF as a chronic condition. CONCLUSIONS The findings provide preliminary support for the self-regulatory model, using the necessity-concerns framework to operationalize treatment beliefs, in explaining adherence to treatment in adolescents with CF.

Vitamin B12 deficiency in dementia and cognitive impairment: the effects of treatment on neuropsychological function

Vitamin B12 assay is part of the routine investigation of dementia, although few studies have investigated the effects of treatment on cognition. We examined the effects of B12 treatment on neuropsychological function and disease progression in patients presenting with dementia or cognitive impairment.

Bone mineral density, adiposity, and cognitive functions

Cognitive decline and dementia due to Alzheimers disease (AD) have been associated with genetic, lifestyle, and environmental factors. A number of potentially modifiable risk factors should be taken into account when preventive or ameliorative interventions targeting dementia and its preclinical stages are investigated. Bone mineral density (BMD) and body composition are two such potentially modifiable risk factors, and their association with cognitive decline was investigated in this study. 164 participants, aged 34–87 years old (62.78 ± 9.27), were recruited for this longitudinal study and underwent cognitive and clinical examinations at baseline and after 3 years. Blood samples were collected for apolipoprotein E (APOE) genotyping and dual energy x-ray absorptiometry (DXA) was conducted at the same day as cognitive assessment. Using hierarchical regression analysis, we found that BMD and lean body mass, as measured using DXA were significant predictors of episodic memory. Age, gender, APOE status, and premorbid IQ were controlled for. Specifically, the List A learning from California Verbal Learning Test was significantly associated with BMD and lean mass both at baseline and at follow up assessment. Our findings indicate that there is a significant association between BMD and lean body mass and episodic verbal learning. While the involvement of modifiable lifestyle factors in human cognitive function has been examined in different studies, there is a need for further research to understand the potential underlying mechanisms.

Analysis of spontaneous, conversational speech in dementia of Alzheimer type: Evaluation of an objective technique for analysing lexical performance

Spontaneous, conversational speech in probable dementia of Alzheimer type (DAT) participants and healthy older controls was analysed using eight linguistic measures. These were evaluated for their usefulness in discriminating between healthy and demented individuals. The measures were; noun rate, pronounrate, verb rate, adjective rate, clause-like semantic unit rate (all per 100 words), including three lexical richness measures; type token ratio (TTR), Brunets Index (W) and Honores statistic (R). Results suggest that these measures offer a sensitive method of assessing spontaneous speech output in DAT. Comparison between DAT and healthy older participants demonstrates that these measures discriminate well between these groups. This method shows promise as a diagnostic and prognostic tool, and as a measure for use in clinical trials. Further validation in a large sample of patient versus control ‘norms’ in addition to evaluation in other types of dementia is considered.

Executive dysfunction in OSA before and after treatment: a meta-analysis.

STUDY OBJECTIVES Obstructive sleep apnea (OSA) is a frequent and often underdiagnosed condition that is associated with upper airway collapse, oxygen desaturation, and sleep fragmentation leading to cognitive dysfunction. There is meta-analytic evidence that subdomains of attention and memory are affected by OSA. However, a thorough investigation of the impact of OSA on different subdomains of executive function is yet to be conducted. This report investigates the impact of OSA and its treatment, in adult patients, on 5 theorized subdomains of executive function. DESIGN An extensive literature search was conducted of published and unpublished materials, returning 35 studies that matched selection criteria. Meta-analysis was used to synthesize the results from studies examining the impact of OSA on executive functioning compared to controls (21 studies), and before and after treatment (19 studies); 5 studies met inclusion in both categories. MEASUREMENTS Research papers were selected which assessed 5 subdomains of executive function: Shifting, Updating, Inhibition, Generativity, and Fluid Reasoning. RESULTS All 5 domains of executive function demonstrated medium to very large impairments in OSA independent of age and disease severity. Furthermore, all subdomains of executive function demonstrated small to medium improvements with CPAP treatment. DISCUSSION Executive function is impaired across all five domains in OSA; these difficulties improved with CPAP treatment. Age and disease severity did not moderate the effects found; however, further studies are needed to explore the extent of primary and secondary effects, and the impact of age and premorbid intellectual ability (cognitive reserve).

Neuropsychological effects of sleep loss: implication for neuropsychologists.

There is rapidly accumulating evidence of a close relationship between sleep loss and cognition. Neuropsychologists need to become aware of this body of knowledge as the effects of sleep loss on brain functions are significant. The current study (a) outlines the extent to which insufficient sleep affects performance on cognitive tasks in otherwise healthy people, (b) discusses the relationship between sleep and neurocognitive disorders, and (c) highlights key issues that merit consideration for neuropsychologists. This review shows that sleep loss has a measurable impact on performance through decreases in cognitive functions and effects on biological pathways that support cognitive performance. Sleep loss reliably produces reductions in speed of processing and attention. Higher order cognitive functions are affected to a lesser extent, and there is sparing on tasks of crystallized abilities. Deficits worsen with increasing time awake, but may be overturned after normal sleep is resumed. The review also shows that sleep disorders are a major feature of neuropsychological conditions contributing to the pattern of cognitive impairment. Overall, neuropsychologists must be alert to sleep problems in their clients, so that sleep interventions, or referrals, are put in place in the rehabilitation plan of individuals with cognitive dysfunctions. Recommendations also include routine screening of sleep as part of cognitive assessment.

Memory for Intentions is Uniquely Associated with Instrumental Activities of Daily Living in Healthy Older Adults

Moderate declines in prospective memory (PM) are common among older adults, but whether such decrements are associated with everyday functioning problems is not well established. To examine this issue, we administered the Memory for Intentions Screening Test (MIST), Prospective and Retrospective Memory Questionnaire (PRMQ), and Activities of Daily Living Questionnaire (ADLQ) to 50 healthy older Australian adults as part of a broader neuropsychological battery. In a series of hierarchical regressions controlling for demographics, medical/psychiatric factors, and other neurocognitive functions, the MIST event-based PM score and PRMQ PM scale were significantly associated with the total number of instrumental ADL (IADL) domains in which participants reported needing assistance. Extending prior findings in clinical populations, results indicate that lower PM functioning is uniquely associated with mild, concurrent IADL problems in healthy older adults. Future investigation of the potentially moderating effects of cognitive and behavioral compensatory strategies may be beneficial.

Neuropsychological prediction of conversion to dementia from questionable dementia: statistically significant but not yet clinically useful

Background: Verbal memory impairment, one of the earliest signs of Alzheimer’s disease (AD), may help identify people with cognitive impairment, insufficient for a diagnosis of dementia (questionable dementia: QD), at risk of developing AD. Other cognitive parameters have been found that may indicate which people with QD will go on to develop dementia. Nevertheless, some researchers have reported only partial success in differentiating between mild AD and age related cognitive impairment. Objectives: To discover if there are early, pre-clinical cognitive markers that could help identify patients attending our memory clinic who were at risk of developing dementia. Methods: Multidisciplinary assessment of a consecutive sample of 195 patients with QD seen in a National Health Service hospital outpatient clinic; 135 seen for a mean follow up of 24.5 months. Results: Conversion rate to dementia was 27.4% (37 of 135). A diagnosis of probable or possible AD was made in 15.6% (21 of 135) of cases. Despite statistically significant differences in some cognitive tasks between those who did and those who did not go on to dement, Cox regression analyses failed to improve prediction rates markedly above base rates and were unstable. Conclusion: A large number of studies claim good prediction of conversion to dementia using cognitive test scores. Although this study produced similarly good sensitivity and specificity values, proper consideration of the statistical analyses and their clinical significance suggested that these prediction methods are currently too imprecise for clinical use. Use of cognitive indicators combined with neuroradiological, neuropathological, and genetic factors for predicting conversion to dementia might prove more reliable but may be beyond the scope of many geriatric services.