The benefits of organic farming for biodiversity

Previous studies suggest widespread positive responses of biodiversity to organic farming. Many of these studies, however, have been small-scale. This project tested the generality of habitat and biodiversity differences between matched pairs of organic and non-organic farms containing cereal crops in lowland England on a large-scale across a range of taxa including plants, insects, birds and bats. The extent of both cropped and un-cropped habitats together with their composition and management on a range of scales were also compared. Organic farms was likely to favour higher levels of biodiversity and indeed organic farms tended to support higher numbers of species and overall abundance across most taxa. However, the magnitude of the response differed strikingly; plants showed stronger and more consistent responses than other taxa. Some, but not all, differences in biodiversity between systems appear to be a consequence of differences in habitat quantity

Time-Resolved Diffusing Wave Spectroscopy for selected photon paths beyond 300 transport mean free paths

This paper is devoted to the theoretical and experimental demonstration of the possibility to perform time-resolved diffusing wave spectroscopy: we successfully registered field fluctuations for selected photon path lengths that can overpass 300 transport mean free paths. Such a performance opens new possibilities for biomedical optics applications.Comment: 12 pages, 3 figure

Progressive cortical thinning and subcortical atrophy in dementia with Lewy bodies and Alzheimer's disease.

Patterns of progressive cortical thinning in dementia with Lewy bodies (DLB) remain poorly understood. We examined spatiotemporal patterns of cortical thinning and subcortical atrophy over 12 months in DLB (n = 13), compared with Alzheimer's disease (AD) (n = 23) and healthy control subjects (HC) (n = 33). Rates of temporal thinning in DLB were relatively preserved compared with AD. Volumetric analyses subcortical changes revealed that the AD group demonstrated significantly increased hippocampal atrophy (-5.8%) relative to the HC (-1.7%; p < 0.001) and DLB groups (-2.5%, p = 0.006). Significant lateral ventricular expansion was also observed in AD (8.9%) compared with HC (4.3%; p < 0.001) and DLB (4.7%; p = 0.008) at trend level. There was no significant difference in subcortical atrophy and ventricular expansion between DLB and HC. In the DLB group, increased rates of cortical thinning in the frontal and parietal regions were significantly correlated with decline in global cognition (Mini-Mental State Examination) and motor deterioration (Unified Parkinson's Disease Rating Scale 3), respectively. Overall, AD and DLB are characterized by different spatiotemporal patterns of cortical thinning over time. Our findings warrant further consideration of longitudinal cortical thinning as a potential imaging marker to differentiate DLB from AD.This work was supported by the Sir Jules Thorn Charitable Trust (Grant number 05/JTA), the NIHR Biomedical Research Unit in Dementia and the Biomedical Research Centre awarded to Cambridge University Hospitals NHS Foundation Trust and the University of Cambridge, and the NIHR Biomedical Research Unit in Dementia and the Biomedical Research Centre awarded to Newcastle upon Tyne Hospitals NHS Foundation Trust and the Newcastle University. Elijah Mak was in receipt of a Gates Cambridge PhD studentship. Elijah Mak formulated the research question, performed the statistical analyses, interpreted the results, and wrote the article. Li Su and Guy Williams assisted with the interpretation of the results and provided comments and additional suggestions for revisions of the draft. Rosie Watson recruited and assessed study participants, assisted with the interpretation of the results, and reviewed the article. Michael Firbank designed the imaging protocol, assisted with the interpretation of the results, and reviewed the article. Andrew Blamire obtained funding for the project, designed the imaging protocol, undertook routine quality assurance on the MR system, assisted with the interpretation of the results, and reviewed the article. John O’Brien obtained funding for the project, designed the imaging protocol, assisted with recruitment of study participants, assisted with the interpretation of the results, and reviewed the article. All authors approved the final article.This is the accepted manuscript for a paper published in Neurobiology of Aging Volume 36, Issue 4, April 2015, Pages 1743–1750, DOI: 10.1016/j.neurobiolaging.2014.12.03

Longitudinal diffusion tensor imaging in dementia with Lewy bodies and Alzheimer's disease.

OBJECTIVE: Changes in the white matter of dementia with Lewy bodies (DLB) and Alzheimer's disease (AD) have been reported using diffusion weighted MRI, though few longitudinal studies have been done. METHODS: We performed diffusion weighted MRI twice, a year apart on 23 AD, 14 DLB, and 32 healthy control subjects. Mean diffusivity (MD) and fractional anisotropy (FA) were calculated. RESULTS: In AD, there were widespread regions where the longitudinal MD increase was greater than in controls, and small areas in the parietal and temporal lobes where it was greater in AD than DLB. In AD, decrease in brain volume correlated with increased MD. There were no significant differences in progression between DLB and controls. CONCLUSIONS: In AD the white matter continues to degenerate during the disease process, whereas in DLB, changes in the white matter structure are a relatively early feature. Different mechanisms are likely to underpin changes in diffusivity.The study was supported by the NIHR Biomedical Research Unit in Dementia and the Biomedical Research Centre awarded to Cambridge University Hospitals NHS Foundation Trust and the University of Cambridge, and the NIHR Biomedical Research Unit in Dementia and the Biomedical Research Centre awarded to Newcastle upon Tyne Hospitals NHS Foundation Trust and Newcastle University. Elijah Mak was in receipt of a Gates Cambridge PhD studentship.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.parkreldis.2016.01.00

Long term incidence of dementia, predictors of mortality and pathological diagnosis in older stroke survivors

Greater understanding of the risk factors and mechanisms of incident dementia in stroke survivors is needed for prevention and management. There is limited information on the long-term consequences and forms of incident dementia in older stroke survivors. We recruited 355 patients aged >75 years from hospital-based stroke registers into a longitudinal study 3 months after stroke. At baseline none of the patients had dementia. Patients were genotyped for apolipoprotein E and assessed annually for cognition and development of incident dementia over up to 8 years of follow-up. The effect of baseline vascular risk factors upon incidence of dementia and mortality were estimated by Cox proportional regression analyses adjusted for age and gender. Standard neuropathological examination was performed to diagnose the first 50 cases that came to autopsy. We found that the median survival from the date of the index stroke was 6.72 years (95% confidence intervals: 6.38–7.05). During the follow-up of a mean time of 3.79 years, 23.9% of subjects were known to have developed dementia and 76.1% remained alive without dementia or died without dementia. The incidence of delayed dementia was calculated to be 6.32 cases per 100 person years whereas that for death or dementia was 8.62. Univariate and multivariate regression analyses showed that the most robust predictors of dementia included low (1.5 standard deviations below age-matched control group) baseline Cambridge Cognitive Examination executive function and memory scores, Geriatric Depression Scale score and three or more cardiovascular risk factors. Autopsy findings suggested that remarkably ≥75% of the demented stroke survivors met the current criteria for vascular dementia. Demented subjects tended to exhibit marginally greater neurofibrillary pathology including tauopathy and Lewy bodies and microinfarcts than non-demented survivors. Despite initial improvements in cognition following stroke in older stroke survivors, risk of progression to delayed dementia after stroke is substantial, but is related to the presence of vascular risk factors. Careful monitoring and treatment of modifiable vascular risk factors may be of benefit in preventing post-stroke dementia in the general population

Predicting cognitive decline using neuropsychiatric symptoms in prodromal Lewy body dementia: A longitudinal study

Introduction: Neuropsychiatric symptoms (NPS) in Lewy body dementias (LBD) occur frequently and early in disease progression. Such symptoms are associated with worse quality of life, caregiver burden and functional limitations. Limited evidence exists, however, outlining the longitudinal relationship between NPS and cognitive decline in prodromal LBD. Methods: 123 participants were derived from three cohort studies. Patients with mild cognitive impairment (MCI) relating to probable dementia with Lewy bodies (MCI-LB, n = 67) and Parkinson's disease (PD-MCI, n = 56) completed comprehensive cognitive and neuropsychiatric assessment and were followed up longitudinally. Linear regression and mixed effects models assessed the relationship between baseline NPS and cognition at baseline and over time. Results: In MCI-LB, overall NPS burden was associated with declines over time in executive function (p = 0.026) and processing speed (p = 0.028) and baseline aberrant motor behaviour was associated with declines in attention (p < 0.025). Anxiety was significantly associated with poorer visuospatial functioning (p = 0.016) at baseline and poorer attention both at baseline (p = 0.017) and across time points (p = 0.024). In PD-MCI, psychosis was associated with poorer executive functioning at baseline (p = 0.008) and across time points (p = 0.002) but had no association with changes longitudinally. Conclusions: Core neuropsychiatric components of LBD are not strongly associated with cognition in prodromal disease. This may suggest that neuropathological mechanisms underlying NPS may not be the same as those underlying cognitive impairment. Non-core NPS, however, may be more directly associated with cognitive change. Future studies utilising neuroimaging techniques are needed to explore the neuropathological basis of NPS in prodromal LBD

Dysfunctional brain dynamics and their origin in Lewy body dementia.

Lewy body dementia includes dementia with Lewy bodies and Parkinson's disease dementia and is characterized by transient clinical symptoms such as fluctuating cognition, which might be driven by dysfunction of the intrinsic dynamic properties of the brain. In this context we investigated whole-brain dynamics on a subsecond timescale in 42 Lewy body dementia compared to 27 Alzheimer's disease patients and 18 healthy controls using an EEG microstate analysis in a cross-sectional design. Microstates are transiently stable brain topographies whose temporal characteristics provide insight into the brain's dynamic repertoire. Our additional aim was to explore what processes in the brain drive microstate dynamics. We therefore studied associations between microstate dynamics and temporal aspects of large-scale cortical-basal ganglia-thalamic interactions using dynamic functional MRI measures given the putative role of these subcortical areas in modulating widespread cortical function and their known vulnerability to Lewy body pathology. Microstate duration was increased in Lewy body dementia for all microstate classes compared to Alzheimer's disease (P < 0.001) and healthy controls (P < 0.001), while microstate dynamics in Alzheimer's disease were largely comparable to healthy control levels, albeit with altered microstate topographies. Correspondingly, the number of distinct microstates per second was reduced in Lewy body dementia compared to healthy controls (P < 0.001) and Alzheimer's disease (P < 0.001). In the dementia with Lewy bodies group, mean microstate duration was related to the severity of cognitive fluctuations (ρ = 0.56, PFDR = 0.038). Additionally, mean microstate duration was negatively correlated with dynamic functional connectivity between the basal ganglia (r = - 0.53, P = 0.003) and thalamic networks (r = - 0.38, P = 0.04) and large-scale cortical networks such as visual and motor networks in Lewy body dementia. The results indicate a slowing of microstate dynamics and disturbances to the precise timing of microstate sequences in Lewy body dementia, which might lead to a breakdown of the intricate dynamic properties of the brain, thereby causing loss of flexibility and adaptability that is crucial for healthy brain functioning. When contrasted with the largely intact microstate dynamics in Alzheimer's disease, the alterations in dynamic properties in Lewy body dementia indicate a brain state that is less responsive to environmental demands and might give rise to the apparent slowing in thinking and intermittent confusion which typify Lewy body dementia. By using Lewy body dementia as a probe pathology we demonstrate a potential link between dynamic functional MRI fluctuations and microstate dynamics, suggesting that dynamic interactions within the cortical-basal ganglia-thalamic loop might play a role in the modulation of EEG dynamics

Organic farming: biodiversity impacts can depend on dispersal characteristics and landscape context

Organic farming, a low intensity system, may offer benefits for a range of taxa, but what affects the extent of those benefits is imperfectly understood. We explored the effects of organic farming and landscape on the activity density and species density of spiders and carabid beetles, using a large sample of paired organic and conventional farms in the UK. Spider activity density and species density were influenced by both farming system and surrounding landscape. Hunting spiders, which tend to have lower dispersal capabilities, had higher activity density, and more species were captured, on organic compared to conventional farms. There was also evidence for an interaction, as the farming system effect was particularly marked in the cropped area before harvest and was more pronounced in complex landscapes (those with little arable land). There was no evidence for any effect of farming system or landscape on web-building spiders (which include the linyphiids, many of which have high dispersal capabilities). For carabid beetles, the farming system effects were inconsistent. Before harvest, higher activity densities were observed in the crops on organic farms compared with conventional farms. After harvest, no difference was detected in the cropped area, but more carabids were captured on conventional compared to organic boundaries. Carabids were more species-dense in complex landscapes, and farming system did not affect this. There was little evidence that non-cropped habitat differences explained the farming system effects for either spiders or carabid beetles. For spiders, the farming system effects in the cropped area were probably largely attributable to differences in crop management; reduced inputs of pesticides (herbicides and insecticides) and fertilisers are possible influences, and there was some evidence for an effect of non-crop plant species richness on hunting spider activity density. The benefits of organic farming may be greatest for taxa with lower dispersal abilities generally. The evidence for interactions among landscape and farming system in their effects on spiders highlights the importance of developing strategies for managing farmland at the landscape-scale for most effective conservation of biodiversity