Riviste scientifiche

How free speech can become censorship – and how to solve it

New Scientist - Gi, 23/03/2017 - 18:42
The more free speech, the better – or so we thought. But in a world of bots and misinformation, the online free-for-all is ruining debate

Edited live vaccine could stop harmful polio outbreaks

New Scientist - Gi, 23/03/2017 - 17:00
We’re on the brink of eradicating polio, but the virus used as a vaccine can evolve to become dangerous. Now a team has figured out how, and plan to stop it

Chronic pain and depression are linked by brain gene changes

New Scientist - Gi, 23/03/2017 - 16:49
At least 40 per cent of people with severe chronic pain develop depression. A mouse study has found changes in brain gene activity that may explain the link

Phone learns to send app notifications only when you want them

New Scientist - Gi, 23/03/2017 - 16:22
Knowing when you don’t want to be interrupted will help systems manage the deluge of smartphone notifications and wait for a good time

Shock mass coral die-off in Asia sounds alarm for world’s reefs

New Scientist - Gi, 23/03/2017 - 15:00
An unexpected coral bleaching event in the South China Sea shows that reefs can heat up substantially more than the surrounding ocean

Robots are stronger, faster, more durable… and hackable

New Scientist - Gi, 23/03/2017 - 14:35
Some of today's best known robots turn out to be easily hijacked, a sign that this burgeoning tech industry must make security a top priority, says Paul Marks

Best evidence yet that hypnotised people aren’t faking it

New Scientist - Gi, 23/03/2017 - 13:42
It’s hard to tell whether hypnotism is real. Now researchers have used a trick of the mind to show that hypnotised people’s actions really do feel involuntary

Oddball star could be home to long-sought superheavy elements

New Scientist - Gi, 23/03/2017 - 11:49
One of the most chemically strange stars we know could chart a path to the so-called "island of stability", where massive yet relatively stable atoms exist

Moderate drinking may be ‘heart healthy’ but exercise is safer

New Scientist - Gi, 23/03/2017 - 00:30
Another study has found that drinking 14 units or less a week is linked to better cardiovascular health. But drinking alcohol for health is a risky strategy

Can data save rhinos? How to attack wildlife crime at source

New Scientist - Me, 22/03/2017 - 19:00
By the time surveillance technology catches a poacher, it's already too late. Now researchers are training a new generation of technology on the demand for endangered animals, not the supply

A little less ET, a little more astrophysics, if you please

New Scientist - Me, 22/03/2017 - 19:00
The role of science is to rule out the boring and tedious before we embrace the extraordinary, like alien signals or "megastructures", says Geraint Lewis

Old blood can be made young again and it might fight ageing

New Scientist - Me, 22/03/2017 - 19:00
A protein can boost blood stem cells, making them behave like those of younger people. Is it the key to harnessing young blood’s rejuvenating power?

Robots could help children give evidence in child abuse cases

New Scientist - Me, 22/03/2017 - 19:00
Even trained police interviewers find it hard to stay neutral when talking to children who have been abused. Could robots help collect better evidence?

Atomic clocks make best measurement yet of relativity of time

New Scientist - Me, 22/03/2017 - 19:00
Einstein's relativity has survived another test, carried out using a network of synchronised atomic clocks in three European cities

First dinosaurs may have been omnivores in the north hemisphere

New Scientist - Me, 22/03/2017 - 19:00
Largest shake-up of dinosaur family tree in 130 years puts T. rex in a group with herbivores and uproots what we thought we knew about the reptiles

Female fish with bigger brains choose better mates

New Scientist - Me, 22/03/2017 - 19:00
Colourful male guppies are healthier and better foragers. But using this information to pick a good mate requires female guppies to use more brainpower

Quarter of California’s snowpack loss is from human-made warming

New Scientist - Me, 22/03/2017 - 14:28
California’s reservoirs depend on the gradual melting of winter snow in the Sierra Nevada mountains, but the snowpack is dwindling and may not return

Association between fatty acid metabolism in the brain and Alzheimer disease neuropathology and cognitive performance: A nontargeted metabolomic study

PLoS Medicine - Ma, 21/03/2017 - 22:00

by Stuart G. Snowden, Amera A. Ebshiana, Abdul Hye, Yang An, Olga Pletnikova, Richard O’Brien, John Troncoso, Cristina Legido-Quigley, Madhav Thambisetty

Background

The metabolic basis of Alzheimer disease (AD) pathology and expression of AD symptoms is poorly understood. Omega-3 and -6 fatty acids have previously been linked to both protective and pathogenic effects in AD. However, to date little is known about how the abundance of these species is affected by differing levels of disease pathology in the brain.

Methods and findings

We performed metabolic profiling on brain tissue samples from 43 individuals ranging in age from 57 to 95 y old who were stratified into three groups: AD (N = 14), controls (N = 14) and “asymptomatic Alzheimer’s disease” (ASYMAD), i.e., individuals with significant AD neuropathology at death but without evidence for cognitive impairment during life (N = 15) from the autopsy sample of the Baltimore Longitudinal Study of Aging (BLSA). We measured 4,897 metabolite features in regions both vulnerable in the middle frontal and inferior temporal gyri (MFG and ITG) and resistant (cerebellum) to classical AD pathology. The levels of six unsaturated fatty acids (UFAs) in whole brain were compared in controls versus AD, and the differences were as follows: linoleic acid (p = 8.8 x 10−8, FC = 0.52, q = 1.03 x 10−6), linolenic acid (p = 2.5 x 10−4, FC = 0.84, q = 4.03 x 10−4), docosahexaenoic acid (p = 1.7 x 10−7, FC = 1.45, q = 1.24 x 10−6), eicosapentaenoic acid (p = 4.4 x 10−4, FC = 0.16, q = 6.48 x 10−4), oleic acid (p = 3.3 x 10−7, FC = 0.34, q = 1.46 x 10−6), and arachidonic acid (p = 2.98 x 10−5, FC = 0.75, q = 7.95 x 10−5). These fatty acids were strongly associated with AD when comparing the groups in the MFG and ITG, respectively: linoleic acid (p < 0.0001, p = 0.0006), linolenic acid (p < 0.0001, p = 0.002), docosahexaenoic acid (p < 0.0001, p = 0.0024), eicosapentaenoic acid (p = 0.0002, p = 0.0008), oleic acid (p < 0.0001, p = 0.0003), and arachidonic acid (p = 0.0001, p = 0.001). Significant associations were also observed between the abundance of these UFAs with neuritic plaque and neurofibrillary tangle burden as well as domain-specific cognitive performance assessed during life. Based on the regional pattern of differences in brain tissue levels of these metabolites, we propose that alterations in UFA metabolism represent both global metabolic perturbations in AD as well as those related to specific features of AD pathology. Within the middle frontal gyrus, decrements in linoleic acid, linolenic acid, and arachidonic acid (control>ASYMAD>AD) and increases in docosahexanoic acid (AD>ASYMAD>control) may represent regionally specific threshold levels of these metabolites beyond which the accumulation of AD pathology triggers the expression of clinical symptoms. The main limitation of this study is the relatively small sample size. There are few cohorts with extensive longitudinal cognitive assessments during life and detailed neuropathological assessments at death, such as the BLSA

Conclusions

The findings of this study suggest that unsaturated fatty acid metabolism is significantly dysregulated in the brains of patients with varying degrees of Alzheimer pathology.

Dementia in the oldest old: Beyond Alzheimer disease

PLoS Medicine - Ma, 21/03/2017 - 22:00

by Aimee L. Pierce, Claudia H. Kawas

In a Perspective, Aimee Pierce and Claudia Kawas discuss risk factors and pathologies of dementia in the oldest-old.

Age-related cognitive decline and associations with sex, education and apolipoprotein E genotype across ethnocultural groups and geographic regions: a collaborative cohort study

PLoS Medicine - Ma, 21/03/2017 - 22:00

by Darren M. Lipnicki, John D. Crawford, Rajib Dutta, Anbupalam Thalamuthu, Nicole A. Kochan, Gavin Andrews, M. Fernanda Lima-Costa, Erico Castro-Costa, Carol Brayne, Fiona E. Matthews, Blossom C. M. Stephan, Richard B. Lipton, Mindy J. Katz, Karen Ritchie, Jacqueline Scali, Marie-Laure Ancelin, Nikolaos Scarmeas, Mary Yannakoulia, Efthimios Dardiotis, Linda C. W. Lam, Candy H. Y. Wong, Ada W. T. Fung, Antonio Guaita, Roberta Vaccaro, Annalisa Davin, Ki Woong Kim, Ji Won Han, Tae Hui Kim, Kaarin J. Anstey, Nicolas Cherbuin, Peter Butterworth, Marcia Scazufca, Shuzo Kumagai, Sanmei Chen, Kenji Narazaki, Tze Pin Ng, Qi Gao, Simone Reppermund, Henry Brodaty, Antonio Lobo, Raúl Lopez-Anton, Javier Santabárbara, Perminder S. Sachdev, Cohort Studies of Memory in an International Consortium (COSMIC)

Background

The prevalence of dementia varies around the world, potentially contributed to by international differences in rates of age-related cognitive decline. Our primary goal was to investigate how rates of age-related decline in cognitive test performance varied among international cohort studies of cognitive aging. We also determined the extent to which sex, educational attainment, and apolipoprotein E ε4 allele (APOE*4) carrier status were associated with decline.

Methods and findings

We harmonized longitudinal data for 14 cohorts from 12 countries (Australia, Brazil, France, Greece, Hong Kong, Italy, Japan, Singapore, Spain, South Korea, United Kingdom, United States), for a total of 42,170 individuals aged 54–105 y (42% male), including 3.3% with dementia at baseline. The studies began between 1989 and 2011, with all but three ongoing, and each had 2–16 assessment waves (median = 3) and a follow-up duration of 2–15 y. We analyzed standardized Mini-Mental State Examination (MMSE) and memory, processing speed, language, and executive functioning test scores using linear mixed models, adjusted for sex and education, and meta-analytic techniques. Performance on all cognitive measures declined with age, with the most rapid rate of change pooled across cohorts a moderate -0.26 standard deviations per decade (SD/decade) (95% confidence interval [CI] [-0.35, -0.16], p < 0.001) for processing speed. Rates of decline accelerated slightly with age, with executive functioning showing the largest additional rate of decline with every further decade of age (-0.07 SD/decade, 95% CI [-0.10, -0.03], p = 0.002). There was a considerable degree of heterogeneity in the associations across cohorts, including a slightly faster decline (p = 0.021) on the MMSE for Asians (-0.20 SD/decade, 95% CI [-0.28, -0.12], p < 0.001) than for whites (-0.09 SD/decade, 95% CI [-0.16, -0.02], p = 0.009). Males declined on the MMSE at a slightly slower rate than females (difference = 0.023 SD/decade, 95% CI [0.011, 0.035], p < 0.001), and every additional year of education was associated with a rate of decline slightly slower for the MMSE (0.004 SD/decade less, 95% CI [0.002, 0.006], p = 0.001), but slightly faster for language (-0.007 SD/decade more, 95% CI [-0.011, -0.003], p = 0.001). APOE*4 carriers declined slightly more rapidly than non-carriers on most cognitive measures, with processing speed showing the greatest difference (-0.08 SD/decade, 95% CI [-0.15, -0.01], p = 0.019). The same overall pattern of results was found when analyses were repeated with baseline dementia cases excluded. We used only one test to represent cognitive domains, and though a prototypical one, we nevertheless urge caution in generalizing the results to domains rather than viewing them as test-specific associations. This study lacked cohorts from Africa, India, and mainland China.

Conclusions

Cognitive performance declined with age, and more rapidly with increasing age, across samples from diverse ethnocultural groups and geographical regions. Associations varied across cohorts, suggesting that different rates of cognitive decline might contribute to the global variation in dementia prevalence. However, the many similarities and consistent associations with education and APOE genotype indicate a need to explore how international differences in associations with other risk factors such as genetics, cardiovascular health, and lifestyle are involved. Future studies should attempt to use multiple tests for each cognitive domain and feature populations from ethnocultural groups and geographical regions for which we lacked data.

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