Many prey species, including amphibian larvae, can adaptively alter coloration and morphology to become more or less conspicuous to predators. Despite abundant research on predator-induced plasticity ...in tadpoles, the combination of color and morphological responses to predators remains largely unexplored. We measured predator-induced morphological and color plasticity in tadpoles. We reared tadpoles of the neotropical treefrog Dendropsophus ebraccatus with dragonfly nymph or fish predators, or in a predator-free control. After 10 days, we digitally photographed tadpoles and measured eight morphometric variables and five tail color variables. Tadpoles reared with nymphs developed the largest and reddest tails, but incurred a developmental cost, being the smallest overall. Cues from fish induced an opposite tail phenotype in tadpoles, causing shallow achromatic tails. Control tadpoles developed intermediate tail phenotypes. This provides the first experimental evidence that tadpoles can shift both color and morphology in opposite, predator-specific directions in response to a fish and an odonate predator. Despite mean differences, however, there was substantial variation in the degree of phenotype induction across treatments. Tail redness was correlated with tail spot size, but not perfectly, indicating that color and morphology may be partially decoupled in D. ebraccatus. Balancing selection from multiple conflicting predators may result in genetic variation for developmental plasticity.
The frailty syndrome has recently attracted attention of the scientific community and public health organizations as precursor and contributor of age-related conditions (particularly disability) in ...older persons. In parallel, dementia and cognitive disorders also represent major healthcare and social priorities. Although physical frailty and cognitive impairment have shown to be related in epidemiological studies, their pathophysiological mechanisms have been usually studied separately. An International Consensus Group on “Cognitive Frailty” was organized by the International Academy on Nutrition and Aging (I.A.N.A) and the International Association of Gerontology and Geriatrics (I.A.G.G) on April 16th, 2013 in Toulouse (France). The present report describes the results of the Consensus Group and provides the first definition of a “Cognitive Frailty” condition in older adults. Specific aim of this approach was to facilitate the design of future personalized preventive interventions in older persons. Finally, the Group discussed the use of multidomain interventions focused on the physical, nutritional, cognitive and psychological domains for improving the well-being and quality of life in the elderly. The consensus panel proposed the identification of the so-called “cognitive frailty” as an heterogeneous clinical manifestation characterized by the simultaneous presence of both physical frailty and cognitive impairment. In particular, the key factors defining such a condition include: 1) presence of physical frailty and cognitive impairment (CDR=0.5); and 2) exclusion of concurrent AD dementia or other dementias. Under different circumstances, cognitive frailty may represent a precursor of neurodegenerative processes. A potential for reversibility may also characterize this entity. A psychological component of the condition is evident and concurs at increasing the vulnerability of the individual to stressors.
Les syndromes neurologiques fréquemment associés à la présence d’anticorps anti-glutamic acid decarboxylase (GAD) sont le syndrome de l’homme raide et l’ataxie cérébelleuse.
Un homme de 59ans, aux ...antécédents de tabagisme actif et de polyarthrite rhumatoïde, consulta pour une ataxie cérébelleuse d’évolution subaigüe. Il présentait également une encéphalite limbique radioclinique et un syndrome dysautonomique. Le LCR était inflammatoire et le bilan dysimmun révéla la présence d’anticorps anti-GAD dans le sérum. Les anticorps onconeuronaux et notamment les anticorps anti-récepteurs GABAB étaient négatifs. L’évolution neurologique fut favorable après réalisation de trois cures d’immunoglobulines et lors du suivi, un carcinome bronchique à petites cellules fut diagnostiqué permettant une prise en charge oncologique précoce.
Même si la présence d’anticorps anti-GAD est rarement d’origine paranéoplasique, notre observation montre l’intérêt de la recherche d’une néoplasie primitive devant un tableau neurologique associé à ces anticorps.
Cerebellar ataxia and stiff person-syndrome are the main neurological syndromes associated with antibodies to glutamic acid decarboxylase (GAD).
A 59-year-old patient, with history of polymyalgia rheumatica and active smoking, was admitted for subacute cerebellar ataxia and memory dysfunction explained by limbic encephalitis on brain MRI. He also presented with orthostatic hypotension and erectile dysfunction revealing autonomic dysfunction. CSF was inflammatory and antibodies to GAD were positive. Onconeuronal antibodies including GABAB receptor antibodies were negative. Patient's condition quickly improved after intravenous immunoglobulins. A few months later, a small cell lung carcinoma was diagnosed and precociously treated.
This case report underlines the importance of appropriate studies to confirm a primitive neoplasia, when confronted with limbic encephalitis and cerebellar ataxia, even if anti-GAD antibodies rarely define paraneoplastic syndromes.
To compare the power of tests assessing different cognitive domains for the identification of prodromal Alzheimer disease (AD) among patients with mild cognitive impairment (MCI).
Given the early ...involvement of the medial temporal lobe, a precocious and specific pattern of memory disorders might be expected for the identification of prodromal AD.
A total of 251 patients with MCI were tested at baseline by a standardized neuropsychological battery, which included the Free and Cued Selective Recall Reminding Test (FCSRT) for verbal episodic memory; the Benton Visual Retention Test for visual memory; the Deno 100 and verbal fluency for language; a serial digit learning test and the double task of Baddeley for working memory; Wechsler Adult Intelligence Scale (WAIS) similarities for conceptual elaboration; and the Stroop test, the Trail Making test, and the WAIS digit symbol test for executive functions. The patients were followed at 6-month intervals for up to 3 years in order to identify those who converted to AD vs those who remained stable over time. Statistical analyses were based on receiver operating characteristic curve and Cox proportional hazards models.
A total of 59 subjects converted to AD dementia. The most sensitive and specific test for diagnosis of prodromal AD was the FCSRT. Significant cutoff for the diagnosis was 17/48 for free recall, 40/48 for total recall, and below 71% for index of sensitivity of cueing (% of efficacy of semantic cues for retrieval).
The amnestic syndrome of the medial temporal type, defined by the Free and Cued Selective Recall Reminding Test, is able to distinguish patients at an early stage of Alzheimer disease from mild cognitive impairment non-converters.
There is accumulating evidence that involvement in leisure activities may be related to risk of dementia; however, there is no consensus concerning the underlying mechanism of this association. ...Hypothesizing that leisure activities may contribute to cognitive reserve (CR), we examined the association between leisure activities and risk of incident dementia and its subtypes within a general population sample, categorizing leisure activity as stimulating, passive, physical, and social. The possibility that these associations may be driven by other proxies of CR was also examined.
Analyses were carried out on 5,698 dementia-free participants aged 65 and over included in the Three-City cohort study in Dijon and Montpellier (France) in 1999-2001. Hazard ratios (HR) were calculated for incident dementia and its subtypes (mixed/vascular dementia and Alzheimer disease) in relation to category of leisure activity.
Stimulating leisure activities were found to be significantly associated with a reduced risk of dementia (n = 161, HR = 0.49, 95% confidence interval CI: 0.31; 0.79) and Alzheimer disease (n = 105, HR = 0.39, 95% CI: 0.21; 0.71) over the 4-year follow-up 1) independently of other proxies of CR, 2) after adjusting for vascular risk factors, depressive symptoms, and physical functioning, and 3) independently of other leisure activities. Furthermore, no significant association was found with other leisure activities and dementia after controlling for the potential confounders.
Our findings support the hypothesis that cognitively stimulating leisure activities may delay the onset of dementia in community-dwelling elders.
Objective To assess the potential of anticholinergic drugs as a cause of non-degenerative mild cognitive impairment in elderly people. Design Longitudinal cohort study. Setting 63 randomly selected ...general practices in the Montpellier region of southern France. Participants 372 people aged > 60 years without dementia at recruitment. Main outcome measures Anticholinergic burden from drug use, cognitive examination, and neurological assessment. Results 9.2% of subjects continuously used anticholinergic drugs during the year before cognitive assessment. Compared with non-users, they had poorer performance on reaction time, attention, delayed non-verbal memory, narrative recall, visuospatial construction, and language tasks but not on tasks of reasoning, immediate and delayed recall of wordlists, and implicit memory. Eighty per cent of the continuous users were classified as having mild cognitive impairment compared with 35% of non-users, and anticholinergic drug use was a strong predictor of mild cognitive impairment (odds ratio 5.12, P = 0.001). No difference was found between users and non-users in risk of developing dementia at follow-up after eight years. Conclusions Elderly people taking anticholinergic drugs had significant deficits in cognitive functioning and were highly likely to be classified as mildly cognitively impaired, although not at increased risk for dementia. Doctors should assess current use of anticholinergic drugs in elderly people with mild cognitive impairment before considering administration of acetylcholinesterase inhibitors.
A large number of promising candidate disease-modifying treatments for Alzheimer disease (AD) continue to advance into phase II and phase III testing. However, most completed trials have failed to ...demonstrate efficacy, and there is growing concern that methodologic difficulties may contribute to these clinical trial failures. The optimal time to intervene with such treatments is probably in the years prior to the onset of dementia, before the neuropathology has progressed to the advanced stage corresponding to clinical dementia.
An international task force of individuals from academia, industry, nonprofit foundations, and regulatory agencies was convened to discuss optimal trial design in early (predementia) AD.
General consensus was reached on key principles involving the scope of the AD diagnosis, the selection of subjects for trials, outcome measures, and analytical methods.
A consensus has been achieved in support of the testing of candidate treatments in the early (predementia) AD population.
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