Synaptic alterations in the rTg4510 mouse model of tauopathy

Synapse loss, rather than the hallmark amyloid‐β (Aβ) plaques or tau‐filled neurofibrillary tangles (NFT), is considered the most predictive pathological feature associated with cognitive status in the Alzheimer's disease (AD) brain. The role of Aβ in synapse loss is well established, but despite data linking tau to synaptic function, the role of tau in synapse loss remains largely undetermined. Here we test the hypothesis that human mutant P301L tau overexpression in a mouse model (rTg4510) will lead to age‐dependent synaptic loss and dysfunction. Using array tomography and two methods of quantification (automated, threshold‐based counting and a manual stereology‐based technique) we demonstrate that overall synapse density is maintained in the neuropil, implicating synapse loss commensurate with the cortical atrophy known to occur in this model. Multiphoton in vivo imaging reveals close to 30% loss of apical dendritic spines of individual pyramidal neurons, suggesting these cells may be particularly vulnerable to tau‐induced degeneration. Postmortem, we confirm the presence of tau in dendritic spines of rTg4510‐YFP mouse brain by array tomography. These data implicate tau‐induced loss of a subset of synapses that may be accompanied by compensatory increases in other synaptic subtypes, thereby preserving overall synapse density. Biochemical fractionation of synaptosomes from rTg4510 brain demonstrates a significant decrease in expression of several synaptic proteins, suggesting a functional deficit of remaining synapses in the rTg4510 brain. Together, these data show morphological and biochemical synaptic consequences in response to tau overexpression in the rTg4510 mouse model. J. Comp. Neurol., 521:1334–1353, 2013. © 2012 Wiley Periodicals, Inc.     

Cognitive and MRI correlates of orthostatic hypotension in Parkinson’s disease

Orthostatic hypotension (OH) is a frequent nonmotor feature of Parkinson’s disease (PD), and its occurrence has been associated with cognitive impairment. The underlying mechanism could be mediated by development of cerebrovascular disease induced by chronic or episodic hypoperfusion, but the extent of brain vascular load in PD patients with OH has never been investigated. This study aimed to assess the relationship between OH and cognitive function in PD patients and to investigate the contribution of brain vascular lesions. Forty-eight PD patients underwent a tilt table test (TT) to assess supine and orthostatic blood pressure as well as an extensive neuropsychological evaluation to evaluate cognitive function. Brain magnetic resonance imaging was acquired in 44/48 patients and analyzed by a visual semiquantitative scale. Twenty-three patients presented OH at TT (13/23 were symptomatic), and 25 did not. There were no differences in motor severity or disease duration between patients with and without OH. In patients with OH we found significantly worse cognitive performance in specific tasks, such as sustained attention, visuospatial and verbal memory, compared with patients without OH. However, there were no differences in vascular burden between the two groups. Our study confirms that there is an association between OH and selective cognitive deficits in PD, but rebuts the hypothesis that this is underlined by the development of cerebrovascular disease.     

Use of the Gait Profile Score for the evaluation of patients with joint hypermobility syndrome/Ehlers–Danlos syndrome hypermobility type

Gait analysis (GA) is widely used for clinical evaluations in various pathological states, both in children and in adults, such as in patients with joint hypermobility syndrome/Ehlers–Danlos syndrome hypermobility type (JHS/EDS-HT). Otherwise, GA produces a large volume of data and there is the clinical need to provide also a quantitative measure of the patient's overall gait. Starting from this aim some global indexes were proposed by literature as a summary measure of the patient's gait, such as the Gait Profile Score (GPS). While validity of the GPS was demonstrated for the evaluation of the functional limitation of children with Cerebral Palsy, no studies have been conducted in patients JHS/EDS-HT. The aim of our study was therefore to investigate the effectiveness of the GPS in the quantification of functional limitation of patients with JHS/EDS-HT. Twenty-one adult (age: 36.1 ± 12.7 years) individuals with JHS/EDS-HT were evaluated using GA and from GA data the GPS was computed. The results evidenced that the GPS value of patients was 8.9 ± 2.6, statistically different from 4.6 ± 0.9 displayed by the control group. In particular, all values of Gait Variable Scores (GVS) which compose the GPS were higher if compared to controls, with the exception of Pelvic Tilt and Foot Progression. The correlations between GPS/GVS and Lower Extremity Functional Scale (LEFS) showed significant relationship between GPS and the item 11 (“Walking 2 blocks”) (ρ = ?0.56; p < 0.05) and 12 (“Walking a mile”) of LEFS (ρ = ?0.76; p < 0.05). Our results showed that GPS and GVS seem to be appropriate outcome measures for the evaluation of the functional limitation during gait of patients with JHS/EDS-HT.     

Pathological gambling in Parkinson's disease: Subthalamic oscillations during economics decisions

Pathological gambling develops in up to 8% of patients with Parkinson's disease. Although the pathophysiology of gambling remains unclear, several findings argue for a dysfunction in the basal ganglia circuits. To clarify the role of the subthalamic nucleus in pathological gambling, we studied its activity during economics decisions. We analyzed local field potentials recorded from deep brain stimulation electrodes in the subthalamic nucleus while parkinsonian patients with (n = 8) and without (n = 9) pathological gambling engaged in an economics decision‐making task comprising conflictual trials (involving possible risk‐taking) and non conflictual trials. In all parkinsonian patients, subthalamic low frequencies (2–12 Hz) increased during economics decisions. Whereas, in patients without gambling, low‐frequency oscillations exhibited a similar pattern during conflictual and non conflictual stimuli, in those with gambling, low‐frequency activity increased significantly more during conflictual than during non conflictual stimuli. The specific low‐frequency oscillatory pattern recorded in patients with Parkinson's disease who gamble could reflect a subthalamic dysfunction that makes their decisional threshold highly sensitive to risky options. When parkinsonian patients process stimuli related to an economics task, low‐frequency subthalamic activity increases. This task‐related change suggests that the cognitive‐affective system that drives economics decisional processes includes the subthalamic nucleus. The specific subthalamic neuronal activity during conflictual decisions in patients with pathological gambling supports the idea that the subthalamic nucleus is involved in behavioral strategies and in the pathophysiology of gambling. © 2013 International Parkinson and Movement Disorder Society     

Longitudinal study of depression and health status in pregnant women: incidence, course and predictive factors

The aim of this study was to determine the effect of isolated psychological intimate partner violence and psychosocial factors (social support and alcohol or drug use by a partner/family member) on psychological well-being (depression or poor self-perceived health status) at 5 and 12 months post-partum. A longitudinal cohort study was carried out with a consecutive sample of 1,400 women in their first trimester of pregnancy, who attended the prenatal programme in the Valencia Region (Spain) in 2008 and were followed up at 5 months and 12 months post-partum. A logistic regression model was fitted using generalized estimating equations, to assess the effect of isolated psychological intimate partner violence, social support, alcohol consumption and illicit drug use problems by a partner or family member on subsequent psychological well-being at follow-up. We observed a decrease in the incidence of poorer psychological well-being (post-partum depression and poor self-perceived health status) at 12 months post-partum. The strongest predictor of poor psychological well-being was depression (AOR = 6.83, 95 % CI: 3.44–13.58) or poor self-perceived health status (AOR = 5.34, 95 % CI: 2.37–12.02) during pregnancy. Isolated psychological IPV increased the risk of a deterioration in psychological well-being. Having a tangible social network was also a predictor of both post-partum depression and poor self-perceived health status. The effect of functional social support varied according to the type of psychological well-being indicator being used. Problems of alcohol consumption or illicit drug use by a partner or family member were a predictor of post-partum depression only. Psychological well-being during the first year after birth is highly affected by isolated psychological IPV and psychosocial factors.     

Multifocal nivolumab immune-related adverse effects during asymptomatic SARS-CoV-2 infection: causality or casuality?

Neurological Sciences -