1,721,154 research outputs found
Alpha tACS Improves Cognition and Modulates Neurotransmission in Dementia with Lewy Bodies
No full textBackground: Dementia with Lewy bodies (DLB) is characterized by a marked shift of electroencephalographic (EEG) power and dominant rhythm, from the α toward the θ frequency range. Transcranial alternate current stimulation (tACS) is a non-invasive brain stimulation technique that allows entrainment of cerebral oscillations at desired frequencies. Objectives: Our goal is to evaluate the effects of occipital α-tACS on cognitive functions and neurophysiological measures in patients with DLB. Methods: We conducted a double-blind, randomized, sham-controlled, cross-over clinical trial in 14 participants with DLB. Participants were randomized to receive either α-tACS (60 minutes of 3 mA peak-to-peak stimulation at 12 Hz) or sham stimulation applied over the occipital cortex. Clinical evaluations were performed to assess visuospatial and executive functions, as well as verbal episodic memory. Neurophysiological assessments and EEG recordings were conducted at baseline and following both α-tACS and sham stimulations. Results: Occipital α-tACS was safe and well-tolerated. We observed a significant enhancement in visuospatial abilities and executive functions, but no improvement in verbal episodic memory. We observed an increase in short latency afferent inhibition, a neurophysiological marker indirectly and partially dependent on cholinergic transmission, coinciding with an increase in α power and a decrease in Δ power following α-tACS stimulation, effects not seen with sham stimulation. Conclusions: This study demonstrates that occipital α-tACS is safe and enhances visuospatial and executive functions in patients with DLB. Improvements in indirect markers of cholinergic transmission and EEG changes indicate significant neurophysiological engagement. These findings justify further exploration of α-tACS as a therapeutic option for DLB patients. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society
Age-related changes in implicit emotion processing
No full textThe aim of the present study was to compare the performance of older and younger adults on an emotional priming task. Moreover, a nonemotional priming paradigm was used as a control task to disentangle age-related changes due to emotional processing difficulties from modifications due to a decline of executive inhibitory control abilities. Twenty-two young and 22 older healthy participants completed an emotional priming task and a nonemotional priming task. In the older adult group, reaction times in the emotional priming paradigm were not influenced by any of the prime conditions, whereas both groups exhibited similar facilitation effects induced by the congruent prime in the nonemotional task. The selective lack of an emotional priming effect in older adults shown in this preliminary report suggests that aging-induced changes in the ability to recognize emotions implicitly are directly dependent on emotional processing difficulties and not due to a general age-related modification of cognitive processes
Better together: Left and right hemisphere engagement to reduce age-related memory loss
No full textEpisodic memory is a cognitive function that appears more susceptible than others to the effects of aging. The main aim of this study is to investigate if the magnitude of functional hemispheric lateralization during episodic memory test was positively correlated with memory performance, proving the presence of a beneficial pattern of neural processing in high-performing older adults but not in low-performing participants.We have applied anodal transcranial Direct Current Stimulation (tDCS) or sham stimulation over left and right hemisphere in a group of young subjects and in high-performing and low-performing older participants during an experimental verbal episodic memory task.Remarkably, young individuals and high-performing older adults exhibited similar performances on episodic memory tasks and both groups showed symmetrical recruitment of left and right areas during memory retrieval. In contrast, low-performing older adults, who obtained lower scores on the memory tasks, demonstrated a greater engagement of the left hemisphere during verbal memory task. Furthermore, structural equation model was performed for analyzing the interrelations between the index of interhemispheric asymmetry and several neuropsychological domains. We found that the bilateral engagement of dorsolateral prefrontal cortex and parietal cortex regions had a direct correlation with memory and executive functions evaluated as latent constructs. These findings drew attention to brain maintenance hypothesis. The potential of neurostimulation in cognitive enhancement is particularly promising to prevent memory loss during aging
Alpha tACS Improves Cognition and Modulates Neurotransmission in Dementia with Lewy Bodies
Full text linkBackground: Dementia with Lewy bodies (DLB) is characterized by a marked shift of electroencephalographic (EEG) power and dominant rhythm, from the α toward the θ frequency range. Transcranial alternate current stimulation (tACS) is a non-invasive brain stimulation technique that allows entrainment of cerebral oscillations at desired frequencies. Objectives: Our goal is to evaluate the effects of occipital α-tACS on cognitive functions and neurophysiological measures in patients with DLB. Methods: We conducted a double-blind, randomized, sham-controlled, cross-over clinical trial in 14 participants with DLB. Participants were randomized to receive either α-tACS (60 minutes of 3 mA peak-to-peak stimulation at 12 Hz) or sham stimulation applied over the occipital cortex. Clinical evaluations were performed to assess visuospatial and executive functions, as well as verbal episodic memory. Neurophysiological assessments and EEG recordings were conducted at baseline and following both α-tACS and sham stimulations. Results: Occipital α-tACS was safe and well-tolerated. We observed a significant enhancement in visuospatial abilities and executive functions, but no improvement in verbal episodic memory. We observed an increase in short latency afferent inhibition, a neurophysiological marker indirectly and partially dependent on cholinergic transmission, coinciding with an increase in α power and a decrease in Δ power following α-tACS stimulation, effects not seen with sham stimulation. Conclusions: This study demonstrates that occipital α-tACS is safe and enhances visuospatial and executive functions in patients with DLB. Improvements in indirect markers of cholinergic transmission and EEG changes indicate significant neurophysiological engagement. These findings justify further exploration of α-tACS as a therapeutic option for DLB patients. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society
The role of the motor system in action naming in patients with neurodegenerative extrapyramidal syndromes
No full textPrevious studies of patients with brain damage have suggested a close relationship between aphasia and movement disorders. Neurodegenerative extrapyramidal syndromes associated with cognitive impairment provide an interesting model for studying the neural substrates of cognitive and motor symptoms. In this review, we focused on studies investigating language production abilities in patients with Parkinson's disease (PD), Corticobasal Syndrome (CBS) and Progressive Supranuclear Palsy (PSP). According to some reports, these patients exhibit a reduction in performance in both action and object naming or verb production compared to healthy individuals. Furthermore, a disproportional impairment of action naming compared to object naming was systematically observed in patients with these disorders. The study of these clinical conditions offers the unique opportunity to examine the close link between linguistic features and motor characteristics of action. This particular pattern of language impairment may contribute to the debate on embodiment theory and on the involvement of the basal ganglia in language and in integrating language and movement. From a translational perspective, we suggest that language ability assessments are useful in the clinical work-up, along with neuropsychological and motor evaluations. Specific protocols should be developed in the near future to better characterize language deficits and to permit an early cognitive diagnosis. Moreover, the link between language deficits and motor impairment opens a new issue for treatment approaches. Treatment of one of these two symptoms may ameliorate the other, and treating both may produce a greater improvement in patients' global clinical conditions
Transcranial direct current stimulation combined with cognitive training for the treatment of Parkinson Disease: a randomized, placebo-controlled study
No full textBackground: A number of non-motor symptoms occurs in Parkinson Disease (PD), cognitive decline and mood disturbances representing the most prevalent. Recent studies reported that cognitive training could potentially help to attenuate cognitive deficits in patients with PD and several researches demonstrated a beneficial effect of active transcranial Direct Current Stimulation (tDCS) over the left dorsolateral prefrontal cortex (anode over left dorsolateral prefrontal cortex, cathode over right supraorbital area) on cognitive deficits and mood disturbances. Objective: To investigate the effects of active tDCS combined with computerized cognitive training on cognition and mood disturbances in PD patients. Methods: Twenty-two patients with PD were assigned to either active tDCS plus computerized cognitive training (CCT) or sham tDCS plus CCT groups. Each patient underwent two weeks’ treatment of daily application of tDCS for 25 minutes during CCT focalized on functions related with prefrontal cortex. Each patient was evaluated at baseline, after treatment and at 3-month follow-up. Results: A significant reduction of depressive symptoms was observed in the active tDCS group from baseline to post-treatment assessment and from baseline to 3-month follow-up. An improvement in cognitive performances, referring more specifically to language, attentional and executive functions, was observed in both groups post-treatment and at follow-up. However, phonemic verbal fluency showed significant greater changes from baseline in the active tDCS group. Conclusions: We concluded that cognitive training along with active tDCS is a useful combined approach in the management of mood and cognitive dysfunctions in PD
Cognitive telerehabilitation in mild cognitive impairment, Alzheimer’s disease and frontotemporal dementia: a systematic review
No full textIntroduction: Given the limited effectiveness of pharmacological treatments, non-pharmacological interventions in neurodegenerative diseases have gained increasing attention in recent years and telerehabilitation has been proposed as a cognitive rehabilitation strategy. The purpose of this systematic review is to examine the evidence for the efficacy of cognitive telerehabilitation interventions compared with face-to-face rehabilitation in patients with mild cognitive impairment, Alzheimer’s disease and frontotemporal dementia. Methods: In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a systematic search of the Medline database was conducted. Out of 14 articles assessed for eligibility, five studies were identified, three in participants with mild cognitive impairment or Alzheimer’s disease, two in patients with primary progressive aphasia. Results: The Physiotherapy Evidence Database scale was used to assess the methodological quality of four out of five studies included in this systematic review, with only one report receiving a high-quality rating. Effect-size analysis evidenced positive effects of telerehabilitation interventions, comparable with those reported for face-to-face rehabilitation. Discussion: The available evidence for the effectiveness of cognitive telerehabilitation is limited, and the quality of the evidence needs to be improved. The systematic review provides preliminary evidence suggesting that cognitive telerehabilitation for neurodegenerative disease may have comparable effects as conventional in-person cognitive rehabilitation
Facial feedback effect explains the autonomic impairment in PD for emotional recognition
No full textParkinson’s Disease (PD) is a degenerative neurological disorder of the central
nervous system with a strong impact on both social and emotional level. Parkinson
patients typically present with emotional processing impairment in emotional
experience and emotion recognition. However, it is not yet known whether these
patients have lost the capability to feel the emotions intrinsically, to modulate to
emotional experience associating subjective response with physiological modulations,
or to decipher emotions in others. The present research aims at investigating
the contribution of central, peripheral and facial feedback measures in PD patients
when they processed emotional cues using a multilevel approach, comparting selfreport
(appraisal), autonomic (Skin Conductance Response, SCR) and motor electromyographic
(EMG zygomaticus and corrugators facial muscles) measures. The
integration of these measures allowed firstly a direct comparison between the explicit
appraisal of emotions (with specific reference to the two parameters of valence and
arousal) and the autonomic responsiveness to emotions. Secondly the role of EMG
(zygomaticus and corrugators muscle) in determining the central and peripheral
modulation was explored. Indeed the facial feedback model supposed that the
autonomic facial response by facial muscles may affect both the emotional appraisal
and the physiological modulation. 20 patients have been selected and 34 healthy
volunteers (HC), matched for age and education. PD patients observed and evaluated
affective pictures that were chosen from International Affective Picture System
(IAPS). These pictures concerned four types of stimuli: 10 pleasant – low and high
arousal; 10 unpleasant – low and high arousal, 5 neutral. PD patients seemed to
not adequately answer to the emotional categories which were considered salient in
standard conditions (HC). Indeed, there was an autonomic impairment for a category-
specific emotion (negative and high arousal). Particularly, patients have revealed
an inadequate sensibility (reduced SCR) only for negative emotional condition. In
parallel EMG behavior was disrupted (reduced corrugators activity) in response to
negative high arousal emotional cues. However, PD patients were able to correctly
categorize the emotional cues based on their valence/arousal, probably due to a “gap”
between this central process and the autonomic system activity. Then, the regression
analysis pointed out the predictive role of the corrugators activity to explain the
impaired autonomic response: a reduced corrugators mimic was linked to a reduced
peripheral responsiveness toward the negative and high arousal emotional stimuli
Predicting Alzheimer's disease severity by means of TMS–EEG coregistration
No full textClinical manifestations of Alzheimer's disease (AD)are associated with a breakdown in large-scale communication, such that AD may be considered as a “disconnection syndrome.” An established method to test effective connectivity is the combination of transcranial magnetic stimulation with electroencephalography (TMS–EEG)because the TMS-induced cortical response propagates to distant anatomically connected regions. To investigate whether prefrontal connectivity alterations may predict disease severity, we explored the relationship of dorsolateral prefrontal cortex connectivity (derived from TMS–EEG)with cognitive decline (measured with Mini Mental State Examination and a face–name association memory task)in 26 patients with AD. The amplitude of TMS–EEG evoked component P30, which was found to be generated in the right superior parietal cortex, predicted Mini Mental State Examination and face–name memory scores: higher P30 amplitudes predicted poorer cognitive and memory performances. The present results indicate that advancing disease severity might be associated with effective connectivity increase involving long-distance frontoparietal connections, which might represent a maladaptive pathogenic mechanism reflecting a damaged excitatory–inhibitory balance between anterior and posterior regions
Cognitive reserve predicts episodic memory enhancement induced by transcranial direct current stimulation in healthy older adults
Full text linkEpisodic memory shows the largest degree of age-related decline. Anodal transcranial Direct Current Stimulation (tDCS) can enhance episodic memory in aging but there is also evidence of response variability even when using identical stimulation parameters. To explore which inter-individual factors (i.e. age, education, encoding performance, cognitive reserve, tDCS group and timing of tDCS application) may directly and/or indirectly modulate verbal memory recall, we used data from our previous tDCS studies that showed enhanced episodic memory recall in 80 healthy older adults. In these studies we used the same paradigm and stimulation parameters but tDCS was applied during different memory stages. Memory recall was tested 48 hours and 30 days after encoding. Univariate regression models showed that tDCS group (Anodal vs. Sham) predicted memory recall, indicating higher scores in the Anodal group than in the Sham group. Encoding performance predicted memory recall in both tDCS groups. Multiple regression models revealed that cognitive reserve, measured with a life experience questionnaire, predicted memory recall only for the Anodal group. Higher cognitive reserve was linked to better memory recall. Accounting for individual differences in cognitive reserve at baseline helps to explain tDCS responsiveness. This knowledge may contribute to optimize its use in older adults
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