Bearded capuchin monkeys as a model for Alzheimer's disease.

The absence of a natural animal model is one of the main challenges in Alzheimer's disease research. Despite the challenges of using nonhuman primates in studies, these animals can bridge mouse models and humans, as nonhuman primates are phylogenetically closer to humans and can spontaneously develop AD-type pathology. The capuchin monkey, a New World primate, has recently attracted attention due to its skill in creating and using instruments. We analyzed one capuchin brain using structural 7 T MRI and performed a neuropathological evaluation of three animals. Alzheimer-type pathology was found in the two of the capuchins. Widespread ß-amyloid pathology was observed, mainly in focal deposits with variable morphology and a high density of mature plaques. Notably, plaque-associated dystrophic neurites associated with disruption of axonal transport and early cytoskeletal alteration were frequently found. Unlike in other species of New World monkeys, cerebral arterial angiopathy was not the predominant form of ß-amyloid pathology. Additionally, abnormal aggregates of hyperphosphorylated tau, resembling neurofibrillary pathology, were observed in the temporal and frontal cortex. Astrocyte hypertrophy surrounding plaques was found, suggesting a neuroinflammatory response. These findings indicate that aged capuchin monkeys can spontaneously develop Alzheimer-type pathology, indicating that they may be an advantageous animal model for research in Alzheimer's disease.

Comparative anatomy of the Sapajus sp. (bearded capuchin) hand with comments on tool use in a parallel evolution with the hominid pathway.

Introduction: Bearded capuchins display a wide variety of manipulatory skills and make routine use of tools in both captivity and the wild. The efficient handling of objects in this genus has led several investigators to assume near-human thumb movements, despite a lack of anatomical studies. Methods: Here, we performed an anatomical analysis of muscles and bones in the capuchin hand. Sapajus morphological traits were quantitatively compared with those of humans, chimpanzees, gorillas, and baboons. Results: The comparative analysis indicated that the Sapajus hand is more similar to that of baboons and least similar to that of humans according to the muscles, bones, and three-dimensional data. Furthermore, these findings suggest that bearded capuchins lack true thumb opponency. Regarding manipulatory skills, they display rather primitive hand traits, with limited resources for precision grasping using the opponens pollicis. Discussion: These findings suggest that bearded capuchins' complex use of tools depends more heavily on their high cognitive abilities than on a versatile hand apparatus. These findings offer crucial insights into the evolution of primate cognition.

Bearded capuchin monkey as a model for Alzheimer's disease research.

The absence of a natural animal model is one of the main challenges in Alzheimer's disease research. Despite the challenges of using non-human primates in studies, they can bridge mouse models and humans, as non-human primates are phylogenetically close to humans and can spontaneously develop AD-type pathology. The capuchin monkey, a New World primate, has recently attracted attention due to its skill in creating and using instruments. We analyzed three capuchin brains using structural 7T MRI and neuropathological evaluation. Alzheimer-type pathology was found in one case. Widespread ß-amyloid pathology mainly in the form of focal deposits with variable morphology and high density of mature plaques. Noteworthy, plaque-associated dystrophic neurites, associated with disrupted of axonal transport and early cytoskeletal alteration, were frequently found. Unlike other species of New World monkeys, cerebral arterial angiopathy was not the predominant form of ß-amyloid pathology. Additionally, abnormal aggregates of hyperphosphorylated tau, resembling neurofibrillary pathology, were observed in the temporal and frontal cortex. Besides, astrocyte hypertrophy surrounding plaques was found, suggesting a neuroinflammatory response. Aged capuchin monkeys can spontaneously develop Alzheimer-type pathology, indicating that they may be an advantageous animal model for research in Alzheimer's disease.

The study of rs324420 (C385A) polymorphism of the FAAH gene of the endocannabinoid system in patients with epilepsy and ADHD.

The endocannabinoid (eCB) system regulates many physiological functions in the central nervous system. Fatty acid amide hydrolase (FAAH) is an essential enzyme in the eCB system, degrading anandamide. Single nucleotide polymorphism (SNP) rs324420 is a common genetic polymorphism of the FAAH gene and has been associated with susceptibility to neurological conditions. This study examined whether the SNP rs324420 (C385A) is associated with epilepsy and attention deficit hyperactivity disorder (ADHD). This study consists of two case-control parts. The first part comprises 250 epilepsy subjects and 250 healthy individuals as controls. The second one comprises 157 cases with ADHD and 136 healthy individuals as controls. Genotyping was carried out using polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) technique. Interestingly, the FAAH C384A genotype (OR 1.755, 95 % CI 1.124-2.742, p = 0.013) and allele (OR 1.462, 95 % CI 1.006-2.124, p = 0.046) distribution showed an association with generalized epilepsy. On the other hand, this SNP was not associated with the risk of ADHD. To our knowledge, there was no study on the association between rs324420 (C385A) polymorphism and the risks of ADHD or epilepsy. This study provided the first evidence of an association between generalized epilepsy and rs324420 (C385A) of FAAH. Larger sample sizes and functional studies are warranted to explore the clinical utility of FAAH genotyping as a possible marker for increased generalized epilepsy risk.

Cognitive evaluation following the evolution of brain myofibroblastic tumor in the adolescence: a case study report / Avaliação cognitiva após a evolução do tumor miofibroblástico cerebral na adolescência: relato de estudo de caso

ABSTRACT Objective To report the case of a teenager (12 years old) diagnosed with a brain tumor in the right frontal-parietal region emphasizing the main characteristics observed in neuropsychological examinations. Methods In the pre-surgical evaluation, the patient presented behavioral alterations, including deficits in verbal comprehension, perceptual organization, working memory, processing speed, and slight alterations regarding constructive praxis. Results A reevaluation after two years surgery revealed significant improvement in verbal and perceptual comprehension and constructive praxis while remaining a slight change in processing speed. These results suggest that the tumor's surgical resection produced significant improvements in the patient's neurocognitive context, especially in executive functions. This study also indicates that Neuropsychological evaluation are useful for pre- and post- surgical evaluation of cognitive functioning and its evolution. Conclusion Brain tumor causes cognitive and behavioral changes and its resection can result in improvements in the patient's quality of life.

RESUMO Objetivo Relatar o caso de uma adolescente (12 anos de idade) diagnosticada com tumor cerebral na região frontoparietal direita, enfatizando as principais características observadas em exames neuropsicológicos. Métodos Na avaliação pré-cirúrgica, a paciente apresentou alterações comportamentais, incluindo déficits na compreensão verbal, organização perceptual, memória de trabalho, velocidade de processamento e pequenas alterações na praxia construtiva. Resultados Uma reavaliação dois anos após a cirurgia revelou melhora significativa na compreensão verbal e perceptiva e na práxis construtiva, permanecendo uma ligeira alteração na velocidade de processamento. Esses resultados sugerem que a ressecção cirúrgica do tumor produziu melhoras significativas no contexto neurocognitivo da paciente, sobretudo nas funções executivas. Este estudo também indica que a avaliação neuropsicológica é útil para avaliação pré e pós-cirúrgica do funcionamento cognitivo e sua evolução. Conclusão O tumor cerebral causa alterações cognitivas e comportamentais e a sua ressecção pode resultar em melhorias na qualidade de vida do paciente.

Effective connectivity within the corticothalamic circuit in the neuromyelitis optica patients: A comparative study using resting-state fMRI.

Neuromyelitis Optica, which is known as NMO, is a demyelination syndrome and inflammatory condition of the central nervous system that affects the optic nerves. Since structural imaging approaches cannot adequately describe the brain disorders in patients with NMO, functional magnetic resonance imaging (fMRI) can be used. Resting-state fMRI was performed on 25 healthy subjects and 26 NMO patients. After preprocessing the data, the time series belonging to the regions of the middle frontal gyrus (MFG), inferior frontal gyrus (IFG), precuneus (PRE), thalamus (THA), and middle temporal gyrus (MTG) were extracted as components of the corticothalamic circuit. The obtained time series were statistically analyzed as the input of dynamic causal modeling (DCM) in order to evaluate the effective connectivity within the corticothalamic circuit. The statistical analyses showed that the mean of effective connectivity power was significantly higher in the healthy subjects than in the NMO patients. For the healthy subjects, there was no significant difference in effective connectivity power between the two groups of males and females at the significance level of 0.05. In the NMO patients, there was a significant difference between the effective connectivity levels of the male and female groups only for IFG â†’ MFG, in which it was greater in males than in females. The results of our studies showed that resting-state fMRI could exhibit the difference between healthy and NMO subjects.

Preferential Neuronal Responses to Snakes in the Monkey Medial Prefrontal Cortex Support an Evolutionary Origin for Ophidiophobia.

Ophidiophobia (snake phobia) is one of the most common specific phobias. It has been proposed that specific phobia may have an evolutionary origin, and that attentional bias to specific items may promote the onset of phobia. Noninvasive imaging studies of patients with specific phobia reported that the medial prefrontal cortex (mPFC), especially the rostral part of the anterior cingulate cortex (rACC), and amygdala are activated during the presentation of phobogenic stimuli. We propose that the mPFC-amygdala circuit may be involved in the pathogenesis of phobia. The mPFC receives inputs from the phylogenically old subcortical visual pathway including the superior colliculus, pulvinar, and amygdala, while mPFC neurons are highly sensitive to snakes that are the first modern predator of primates, and discriminate snakes with striking postures from those with non-striking postures. Furthermore, the mPFC has been implicated in the attentional allocation and promotes amygdala-dependent aversive conditioning. These findings suggest that the rACC focuses attention on snakes, and promotes aversive conditioning to snakes, which may lead to anxiety and ophidiophobia.

Cannabidiol attenuated the maintenance and reinstatement of extinguished methylphenidate-induced conditioned place preference in rats.

Methylphenidate (MPH) is a mild CNS stimulant that has been used in hyperactive children, and patients with neurodegenerative and major depressive disorders. Exposure to MPH-associated cues enhances craving and arousal in drug users. On the other hand, cannabidiol (CBD) has antipsychotic potential that might be useful in alleviating symptoms of drug addiction. The aim of this study was to investigate the effect of CBD administration on extinction and reinstatement of MPH-induced conditioning place preference (CPP) in rats. Male rats received MPH (1, 2.5 or 5 mg/kg, i.p) or morphine (5 or 10 mg/kg, s.c.) during the conditioning phase. Following the establishment of CPP, during extinction training, 60 min prior to every CPP session, animals were given daily ICV CBD (10 or 50 µg/5 µL), vehicle alone (DMSO) 10 % or were treatment-naïve. On the reinstatement day animals after receiving the initial dose of MPH, 0.5 mg/kg, and were placed into the CPP box to evaluate the CPP scoring for 10-min. Our findings indicated that morphine (5 and 10 mg/kg; s.c.) and MPH (1 and 2.5 mg/kg; i.p.) induced a CPP. The ICV administration of both doses of CBD (10 and 50 µg/5 µL) prevented the reinstatement of MPH-induced CPP, which displayed shorter extinction latency compared to treatment-naïve or DMSO 10 % groups. Therefore, CBD's site of action is a potential target for reducing the risk of MPH relapse; however, more investigation is required.

Cognitive impairment in Parkinson's disease: A clinical and pathophysiological overview.

Cognitive dysfunction in Parkinson's disease (PD) has received increasing attention, and, together with other non-motor symptoms, exert a significant functional impact in the daily lives of patients. This article aims to compile and briefly summarize selected published data about clinical features, cognitive evaluation, biomarkers, and pathophysiology of PD-related dementia (PDD). The literature search included articles indexed in the MEDLINE/PubMed database, published in English, over the last two decades. Despite significant progress on clinical criteria and cohort studies for PD-mild cognitive impairment (PD-MCI) and PDD, there are still knowledge gaps about its exact molecular and pathological basis. Here we overview the scientific literature on the role of functional circuits, neurotransmitter systems (monoaminergic and cholinergic), basal forebrain, and brainstem nuclei dysfunction in PD-MCI. Correlations between neuroimaging and cerebrospinal fluid (CSF) biomarkers, clinical outcomes, and pathological results are described to aid in uncovering the neurodegeneration pattern in PD-MCI and PDD.

Corticosterone impairs contextual fear recall after reactivation in the ovariectomized rat model of menopause.

Menopause affects most physiological processes, including cognitive functions, although, the extent to which these functions are affected is not clear. The aim of this study was to investigate the effect of corticosterone (CORT) administration after reactivation on contextual fear recall in ovariectomized female rats. Adult female rats were ovariectomized and trained in a fear conditioning chamber (conditioned stimulus, CS) using electrical foot shock (unconditioned stimulus, US); with moderate or strong intensities. After reactivation 48 h later, rats were injected with CORT (0.3, 3 or 10 mg/kg) or vehicle. 2, 4 and 11 days after memory reactivation freezing behavior was scored. The results showed that CORT at the low dose of 0.3 mg/kg when injected after memory reactivation impaired memory recall in both moderate and strong shock on the third test (day 11). Because extinction process occurs after repeated presentation of CS without US (electrical shock during reactivation and recall days), memory impairment in our experiments is more likely to be due to increased memory extinction. Our findings suggest that CORT administration after reactivation of fear memory impairs recall in the rat model of menopause and more research is needed to find the exact mechanisms involved in this process which is of great value for treating cognitive problems during menopause.

A Prototypical Template for Rapid Face Detection Is Embedded in the Monkey Superior Colliculus.

Human babies respond preferentially to faces or face-like images. It has been proposed that an innate and rapid face detection system is present at birth before the cortical visual pathway is developed in many species, including primates. However, in primates, the visual area responsible for this process is yet to be unraveled. We hypothesized that the superior colliculus (SC) that receives direct and indirect retinal visual inputs may serve as an innate rapid face-detection system in primates. To test this hypothesis, we examined the responsiveness of monkey SC neurons to first-order information of faces required for face detection (basic spatial layout of facial features including eyes, nose, and mouth), by analyzing neuronal responses to line drawing images of: (1) face-like patterns with contours and properly placed facial features; (2) non-face patterns including face contours only; and (3) nonface random patterns with contours and randomly placed face features. Here, we show that SC neurons respond stronger and faster to upright and inverted face-like patterns compared to the responses to nonface patterns, regardless of contrast polarity and contour shapes. Furthermore, SC neurons with central receptive fields (RFs) were more selective to face-like patterns. In addition, the population activity of SC neurons with central RFs can discriminate face-like patterns from nonface patterns as early as 50 ms after the stimulus onset. Our results provide strong neurophysiological evidence for the involvement of the primate SC in face detection and suggest the existence of a broadly tuned template for face detection in the subcortical visual pathway.

CB1 receptor antagonism in capuchin monkeys alters social interaction and aversive memory extinction.

RATIONALE: The endocannabinoid system (eCS) is an important modulator of social anxiety and social reward, as well as memory functions. OBJECTIVES: The present study evaluated the role of eCS in social interactions and aversive memory extinction in capuchin monkeys (Sapajus spp.) by blocking the cannabinoid type 1 receptor (CB1r). METHODS: In experiment 1, spontaneous social and non-social behaviors of five capuchin males, each one living in triads with two other females, were observed after AM251 treatment (vehicle, 0.3, 1.0, and 3.0 mg/kg; i.m.). In experiment 2, seven male capuchin monkeys were trained to reach for a reward inside a wooden box. After training, they were given either vehicle or a 3.0-mg/kg i.m. dose of AM251 before a single aversive encounter with a live snake in the box. The latency to return to reach the reward inside the box in subsequent trials was measured. RESULTS: The 3.0-mg/kg dose significantly increased the time spent performing self-directed behaviors, while decreasing that of social interactions. No changes were observed in vigilance or locomotion. AM251 increased the latency to reach the reward after the aversive encounter. CONCLUSION: Taken together, these results suggest that CB1r antagonism induces social deficits without increasing anxiety levels and impairs the extinction of aversive memories. This behavioral profile in monkeys underscores the potential involvement of eCS signaling in the deficits observed in autism spectrum disorders.

Continuous Use of Combined Hormonal Contraceptive and the Effect on Blood Coagulation Factors in Female Capuchin Monkeys (Sapajus libidinosus).

This study aimed at evaluating the availability of the primate Sapajus libidinosus as an animal model for research assessing the physiological effects of the continuous use of combined hormonal contraceptives. In order to do this, six reproductively active female S. libidinosus from the Primate Research Center of the University of Brasília were selected to take part in this experiment. Every 21 days or so, each female received a single dose of combined hormonal contraceptive (algestone acetophenide and 17-enanthate estradiol) in a total of five doses throughout the experiment. The physiological parameters were accessed by means of 13 blood samples from each female, whereas three were gathered during the baseline and 10 samples were collected during the treatment phase. The results showed that the contraceptive use provoked changes in hematological coagulation factors such as an increase in the amount of platelets (p = 0.039) and a reduction in both prothrombin (p < 0.001) and thromboplastin coagulation time (p < 0.001). These results are similar to what has been observed in human patients; thus, it is concluded that S. libidinosus can be successfully used in studies about the physiological impact of hormonal contraceptives.

The effects of oxytocin on primates' working memory depend on the emotional valence of contextual factors.

Current models suggest that neuropeptide oxytocin modulates the salience of emotional/social stimuli and consequently influences perceptual, attentional and learning processes that underlie social behaviour. Therefore, oxytocin has been considered as a potential treatment in managing social and communication deficits in neuropsychological disorders. Recent studies indicate that effects of oxytocin on social and cognitive functions greatly vary and even lead to opposite outcomes. The factors leading to such variabilities in behavioural effects of oxytocin and their underlying mechanisms remain unclear. Here, we examined the effects of exogenously administered (intranasal) oxytocin (48 IU) on cognitive functions of macaque monkeys within a controlled experimental condition in a randomized crossover study. Monkeys performed a working memory task in which they memorized and subsequently matched stimuli with different emotional/social content (positive, negative, and neutral) at different levels of cognitive difficulties (delay period). Monkeys' accuracy was lower at longer delay intervals indicating that higher cognitive demands adversely affected their performance. There was a significant difference in accuracy and response time between the three emotional conditions. The effects of oxytocin on monkeys' performance were dependent on the emotional content of stimuli so that oxytocin enhanced the adverse effects of negative stimuli, however, moderated the effects of positive stimuli. Our findings in monkeys do not support models suggesting a general effect of oxytocin in enhancing salience or heightening of attention to social stimuli and instead suggest that the cognitive effects of oxytocin depend on the emotional valence of contextual factors.

Gamma oscillations in the superior colliculus and pulvinar in response to faces support discrimination performance in monkeys.

The subcortical visual pathway including the superior colliculus (SC), pulvinar, and amygdala has been implicated in unconscious visual processing of faces, eyes, and gaze direction in blindsight. Our previous studies reported that monkey SC and pulvinar neurons responded preferentially to images of faces while performing a delayed non-matching to sample (DNMS) task to discriminate different visual stimuli (Nguyen et al., 2013, 2014). However, the contribution of SC and pulvinar neurons to the discrimination of the facial images and subsequent behavioral performance remains unknown. Since gamma oscillations have been implicated in sensory and cognitive processes as well as behavioral execution, we hypothesized that gamma oscillations during neuronal responses might contribute to achieving the appropriate behavioral performance (i.e., a correct response). In the present study, we re-analyzed those neuronal responses in the monkey SC and pulvinar to investigate possible relationships between gamma oscillations in these neurons and behavioral performance (correct response ratios) during the DNMS task. Gamma oscillations of SC and pulvinar neuronal activity were analyzed in three phases around the stimulus onset [inter-trial interval (ITI): 1000ms before trial onset; Early: 0-200ms after stimulus onset; and Late: 300-500ms after stimulus onset]. We found that human facial images elicited stronger gamma oscillations in the early phase than the ITI and late phase in both the SC and pulvinar neurons. Furthermore, there was a significant correlation between strengths of gamma oscillations in the early phase and behavioral performance in both the SC and pulvinar. The results suggest that gamma oscillatory activity in the SC and pulvinar contributes to successful behavioral performance during unconscious perceptual and behavioral processes.

Delay-Dependent Impairments in Memory and Motor Functions After Acute Methadone Overdose in Rats.

Methadone is used as a substitution drug for the treatment of opioid dependence and chronic pain. Despite its widespread use and availability, there is a serious concern with respect to the relative safety of methadone. The purpose of this study was to characterize how acute methadone overdose affects the cognitive and motor performance of naïve healthy rats. The methadone overdose was induced by administering an acute toxic dose of methadone (15 mg/kg; ip; the equivalent dose of 80% of LD50) to adolescent rats. Resuscitation using a ventilator pump along with a single dose of naloxone (2 mg/kg; ip) was administered following the occurrence of apnea. The animals which were successfully resuscitated divided randomly into three apnea groups that evaluated either on day 1, 5, or 10 post-resuscitation (M/N-Day 1, M/N-Day 5, and M/N-Day 10 groups) in the Y-maze and novel object memory recognition tasks as well as pole and rotarod tests. The data revealed that a single toxic dose of methadone had an adverse effect on spontaneous behavior. In addition, Recognition memory impairment was observed in the M/N-Day 1, 5, and 10 groups after methadone-induced apnea. Further, descending time in the M/N-Day 5 group increased significantly in comparison with its respective Saline control group. The overall results indicate that acute methadone-overdose-induced apnea produced delay-dependent cognitive and motor impairment. We suggest that methadone poisoning should be considered as a possible cause of delayed neurological disorders, which might be transient, in some types of memory or motor performance in naïve healthy rats.

Cannabidiol effects on prepulse inhibition in nonhuman primates.

Prepulse inhibition (PPI) of acoustic startle reflex is a well-established behavior paradigm to measure sensorimotor gating deficits. PPI is disrupted in several neuropsychiatric disorders, including schizophrenia. PPI tests can be used to screen new drugs for treatment of such disorders. In this review, we discuss how PPI paradigm can help in screening the therapeutic effects of cannabidiol (CBD). We look into recent literature about CBD effects on PPI response in animal models, especially in nonhuman primates. CBD has been shown to modify PPI in N-methyl d-aspartate receptor antagonist models for schizophrenia, both in rodents and in nonhuman primates. These results show CBD as a potential drug for the treatment of neurologic disorders that present alterations in sensorimotor system, such as schizophrenia. Moreover, the PPI paradigm seems to be a useful and relative simple paradigm to test the efficacy of CBD as a potential therapeutic drug.

SMR Neurofeedback Training Facilitates Working Memory Performance in Healthy Older Adults: A Behavioral and EEG Study.

Cognitive aging has become a major concern because life expectancy has increased and elderly populations are socially and economically active. Neurofeedback is a technique of neuromodulation through operant conditioning paradigm that uses a computer interface to provide real-time information about brain activity to increase individual self-perception and assist in modulation. The sensorimotor rhythm (SMR) training protocol is known to enhance attention and has been applied to improve cognitive performance, primarily for attention and memory gains. The aim of this study is to test if the SMR protocol can improve working memory performance in an aging population and consequently favor cognitive reserve. Seventeen older adults (12 females) took part in a randomized placebo-controlled study. They completed a visual working memory test, Delayed Matching to Sample Task (DMTS), before and after the SMR neurofeedback protocol in order to compare their visual working memory performance. Moreover, a 19-channels EEG was collected while they perform the DMTS pre- and post-training. The experimental group showed an improvement in their working memory performance after the training with similar activation power, mainly in theta and beta frequency band at frontal and alpha at temporal regions. The sham group showed some variations in the score of working memory after the training, but were not statistically significant and their power spectrum demonstrate enhancement in alpha and beta band frontal and temporal. The group that did not receive neurofeedback training did not show a change in their working memory performance, neither in their EEG spectrum. The results suggest that neurofeedback can benefit brain reserve in an aging population because individuals enhanced their working memory performance after training and have their EEG activation changed according to expected in working memory tasks.

Superior Neuronal Detection of Snakes and Conspecific Faces in the Macaque Medial Prefrontal Cortex.

Snakes and conspecific faces are quickly and efficiently detected in primates. Because the medial prefrontal cortex (mPFC) has been implicated in attentional allocation to biologically relevant stimuli, we hypothesized that it might also be highly responsive to snakes and conspecific faces. In this study, neuronal responses in the monkey mPFC were recorded, while monkeys discriminated 8 categories of visual stimuli. Here, we show that the monkey mPFC neuronal responses to snakes and conspecific faces were unique. First, the ratios of the neurons that responded strongly to snakes and monkey faces were greater than those of the neurons that responded strongly to the other stimuli. Second, mPFC neurons responded stronger and faster to snakes and monkey faces than the other categories of stimuli. Third, neuronal responses to snakes were unaffected by low-pass filtering of the images. Finally, activity patterns of responsive mPFC neurons discriminated snakes from the other stimuli in the second 50 ms period and monkey faces in the third period after stimulus onset. These response features indicate that the mPFC processes fast and coarse visual information of snakes and monkey faces, and support the hypothesis that snakes and social environments have shaped the primate visual system over evolutionary time.

Planning ability impairments in probable Alzheimer's disease patients: Evidence from the Tower of London test.

Alzheimer's disease (AD) is associated with progressive impairment of higher-level cognitive abilities. Previous research suggests that early impairment of executive functions occurs during the course of the disease, but few studies have specifically investigated planning ability in an AD population. OBJECTIVE: The purpose of the current study was to examine whether AD patients retain the ability to plan ahead, by analyzing specificities of their behavior in successfully achieving a pre-established goal. METHODS: Twenty-one AD patients and thirty-three elderly controls underwent a problem-solving assessment using the Tower of London (TOL) test. RESULTS: AD patients were less accurate and less efficient than controls. AD patients also committed more mistakes. This indicates a decline in working memory and inhibitory deficits, resulting in impulsive and inappropriate behaviors. CONCLUSION: These results are in agreement with previous studies, showing executive function problems in patients with AD. Specifically, this study demonstrates the presence of planning ability deficits in AD, considering both qualitative and quantitative approaches. The wide range of analysis presented in this study can aid clinicians in identifying the nature of the poor performance of AD patients during a planning task.

A doença de Alzheimer (DA) é associada a um comprometimento progressivo das habilidades cognitivas superiores. Pesquisas anteriores sugerem que o comprometimento precoce das funções executivas ocorre durante o curso da doença, mas poucos estudos têm investigado especificamente a capacidade de planejamento em uma população com DA. OBJETIVO: O objetivo do presente estudo foi analisar se os pacientes com DA mantêm a capacidade de planejar antecipadamente, analisando as especificidades de seu comportamento para alcançar com êxito uma meta pré-estabelecida. MÉTODOS: Vinte e um pacientes com DA e trinta e três controles idosos foram submetidos a uma avaliação de resolução de problemas utilizando o teste de Torre de Londres (TOL). RESULTADOS: Os pacientes com DA foram menos precisos e menos eficientes do que os controles. Os pacientes com DA também cometeram mais erros. Isso indica um declínio na memória operacional e déficits inibitórios, resultando em comportamentos impulsivos e inadequados. CONCLUSÃO: Estes resultados estão de acordo com estudos anteriores, mostrando problemas de função executiva em pacientes com DA. Especificamente, este estudo demonstra a presença de déficits de capacidade de planejamento na DA, considerando abordagens qualitativas e quantitativas. A ampla gama de análises apresentadas neste estudo poderá auxiliar aos profissionais da área da saúde na identificação da natureza do baixo desempenho dos pacientes com DA durante uma tarefa de planejamento.