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Objective: Our study evaluates how aging and Parkinson's disease (PD) alter temporal order judgment (TOJ)., Method: Two TOJ experiments were performed with young participants, healthy elderly participants, and PD patients. Two white squares were presented on opposite sides of a screen and participants responded which appeared first. In Experiment 1, it was assessed how accurately each group could judge temporal order at intervals from 0ms to 167ms. Detectability, the capacity of detecting which stimulus appeared first, was measured. In Experiment 2, participants were asked to orient their attention to the hemifield indicated by a cue. The PSS ("point of subjective simultaneity"), where the participant was equally likely to respond that either stimulus appeared first, was measured., Results: In Experiment 1, PD patients had smaller detectability than healthy elderly (p<0.05) and young participants (p<0.001), and healthy elderly participants had smaller detectability than young participants (p<0.001). In Experiment 2, PSS was 29ms for young participants, 121ms for healthy elderly participants, and 283ms for PD patients; differences were statistically significant for comparisons between PD patients and healthy elderly participants (p<0.001), PD patients and young participants (p<0.001), and healthy elderly and young participants (p<0.04)., Conclusions: TOJ is impaired by aging and PD. Our results suggest that dopamine loss increases latency and variability in visual decision making due to a lower signal-to-noise ratio in the visual pathways., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

In the central nervous system, the degree of decline in memory retrieval along the aging process depends on the quantity and quality of the stimuli received during lifetime. The cholinergic system modulates long-term potentiation and, therefore, memory processing. This study evaluated the spatial memory, the synaptic plasticity and the density of cholinergic markers in the hippocampi of mice submitted to cognitive stimulation during lifetime or during their aged phase. Male C57Bl/6 mice (2 months old) were exposed to enriched environment during 15 months (EE-15). An age-matched group was left in standard cages during the same period (SC-15). Spatial memory was evaluated using the Barnes maze at 2, 5, 11 and 17 months of age. At the 17-month-old time point, EE-15 mice showed better performance in the spatial memory task (P<0.05), when compared to C-15 mice. Other two groups of mice were left in regular cages until the age of 15 months, and then one of the groups was transferred to an enriched environment for two months (EE-2). The other group was kept in regular cages (C-2). After two months of stimulation, EE-2 showed a significant increase in spatial memory (P<0.01). At the end, brains were extracted and kept at -80°C. Slices were obtained from one hemisphere in a cryostat (20 μm, -18°C) and thaw-mounted on gelatin coated slides. Synaptic densities, cellular bodies, BDNF densities and α4β2 nicotinic cholinergic receptors (nAChR) were evaluated by immunohistochemistry. Autoradiography for α7 nAChR was conducted using [(125)I]-α-bungarotoxin. The other half of the brains was used for Western blotting analysis of choline acetyltransferase (ChAT) density. There was no difference in synaptophysin or MAP-2 densities, but BDNF was increased in some hippocampal areas of EE-15 and EE-2, in comparison to control groups. In the same way, increases in ChAT and α7 densities, but not in α4β2, were observed. Both cognitive stimuli during lifetime or during the aged phase improved spatial memory of mice. No difference in structural plasticity was observed, but the maintenance of memory can be due to improvement in long-term potentiation functionality in the hippocampus, modulated, at least, by BDNF and the cholinergic system., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Objective: In Brazil, not many studies have investigated the validation of cognitive tests in the ageing population and none of them has analyzed the psychometric properties of Tuokko's Clock Test. The objective of the study was to translate and adapt the test to the Brazilian context, and to assess its construct validation., Methods: This is a cross-sectional population-based study, involving 353 elderly patients from Juiz de Fora (Southeastern Brazil), from 2004-2005. To assess convergent and divergent validities Pearson's correlation statistics was used. The Clock Test substests were correlated with theses reference instruments: mini-mental state examination, digits, block design to evaluate the convergent validity. the divergent validity was assessed by comparing the substests to the Center for Epidemiologic Studies Depression Scale., Results: In the sample, 74.1% were women, aged between 63 and 107 years (73.8+/-8.5), average schooling was 7.4 years (SD=4.7). In regard to convergent validity, significant correlations were found between all CT subtests and MMSE, Digits, and Block Design (p<0.01). As for the divergent validity, the only subtest that had significant association with the reference scale was the "clock setting" (p<0.05)., Conclusions: The translated and validated Clock Test into a community sample of aged showed to be a brief screening instrument, with good construct validity when compared to other studies. Future research must investigate other psychometric properties, such as content and criterion validities.