Repetitive Transcranial Magnetic Stimulation as an Alternative Therapy for Cognitive Impairment in Alzheimer's Disease: A Meta-Analysis

Repetitive transcranial magnetic stimulation therapy for motor recovery in Parkinson's disease: A Meta-analysis

INTRODUCTION

Therapeutic effects of repetitive transcranial magnetic stimulation (rTMS) on motor recovery of Parkinson's disease (PD) have been reported; however, the protocols of these studies varied greatly. The aim of this meta-analysis was to evaluate the optimal rTMS parameters for motor recovery of PD.

METHODS

Electronic databases were searched for studies investigating the therapeutic effects of rTMS on motor function in patients with PD. The section III of the Unified Parkinson's Disease Rating Scale (UPDRS) was extracted as the primary outcome, and the standardized mean difference (SMD) with 95% confidence interval (CI) was calculated.

RESULTS

Twenty-three studies with a total of 646 participants were included. The pooled estimates of rTMS revealed significant short-term (SMD, 0.37; p < 0.00001) and long-term (SMD, 0.39; p = 0.005) effects on motor function improvement of PD. Subgroup analysis observed that high-frequency rTMS (HF-rTMS) was significant in improving motor function (SMD, 0.48; p < 0.00001), but low-frequency rTMS (LF-rTMS) was not. In particular, when HF-rTMS targeted over the primary motor cortex (M1), in which the bilateral M1 revealed a larger effect size than unilateral M1. Compared to single-session, multi-session of HF-rTMS over the M1 showed significant effect size. In addition, HF-rTMS over the M1 with a total of 18,000-20,000 stimulation pulses yielded more significant effects (SMD, 0.97; p = 0.01) than other dosages.

CONCLUSIONS

In conclusion, multi-session of HF-rTMS over the M1 (especially bilateral M1) with a total of 18,000-20,000 pulses appears to be the optimal parameters for motor improvement of PD.

Repetitive transcranial magnetic stimulation for the treatment of Alzheimer's disease: A systematic review and meta-analysis of randomized controlled trials

Background

Several studies have demonstrated that repetitive transcranial magnetic stimulation (rTMS) may have a beneficial effect in Alzheimer’s disease (AD). Nevertheless, the clinical benefit of rTMS for AD remains inconclusive.

Objective

This systematic review and meta-analysis aimed to evaluate the efficacy and safety of rTMS in AD.

Methods

We searched PubMed, Embase and Cochrane for randomized controlled trials (RCTs) of rTMS for AD. We calculated pooled estimates of mean difference (MD) with 95% confidence intervals (CI). The protocol was registered at International Prospective Register of Systematic Reviews (PROSPERO) (number CRD42018089990).

Results

Five RCTs involving 148 participants were included in this review. Compared with sham stimulation, high-frequency rTMS led to a significant improvement in cognition as measured by ADAS-cog (MD = -3.65, 95% CI -5.82 to -1.48, p = 0.001), but not MMSE (MD = 0.49, 95% CI -1.45 to 2.42, p = 0.62). High-frequency rTMS also improved the global impression in comparison to the placebo (MD = -0.79, 95% CI -1.24 to -0.34, p = 0.0006). There was no significant difference in mood (MD = -1.36, 95% CI -3.93 to 1.21, p = 0.30) and functional performance (MD = 0.59, 95% CI -1.21 to 2.38, p = 0.52) between high-frequency rTMS and sham groups. Only one trial included low-frequency rTMS reported no significant improvement in cognition, mood and functional performance. Few mild adverse events were observed in both the rTMS and sham groups.

Conclusions

RTMS is relatively well tolerated, with some promise for cognitive improvement and global impression in patients with AD. Our findings also indicate the variability between ADAS-cog and MMSE in evaluating global cognitive impairment.

Transcranial magnetic stimulation intervention in Alzheimer's disease: a research proposal for a randomized controlled trial

Objective

Alzheimer’s disease is a major health problem in our society. To date, pharmacological treatments have obtained poor results and there is a growing interest in finding non-pharmacological interventions for this disease. Transcranial magnetic stimulation (TMS) is a non-invasive technique that is able to induce changes in brain activity and long-term modifications in impaired neural networks, becoming a promising clinical intervention. Our goal is to study the benefit of individualized TMS targeting based on the patient’s functional connectivity (personalized targeting), and short duration TMS protocol, instead of current non-individualized and longer session approaches. A double blind randomized controlled trial will be conducted to assess the effects of TMS treatment immediately, 1 month, 3 months and 6 months after the end of the intervention. Fifty-four patients with a diagnosis of Alzheimer’s disease will be randomly allocated into experimental (active TMS), sham control, or conventional intervention control group. We will quantify changes in cognitive, functional, and emotional deficits in Alzheimer patients, as well as the functional connectivity changes induced by the TMS treatment.

Results

We expect to demonstrate that personalized TMS intervention has a measurable positive impact in cognition, emotion, daily living activities and brain connectivity, thus representing a potential treatment for Alzheimer’s disease.

Trial registration The trial has been prospectively registered at ClinicalTrials.gov, identifier NCT03121066. Date of registration: 04/19/2017

Intranasal insulin in Alzheimer's dementia or mild cognitive impairment: a systematic review

BACKGROUND AND AIMS

Due to common pathophysiological findings of Alzheimer's disease (AD) with diabetes mellitus (DM), insulin has been suggested as a possible treatment of AD or mild cognitive impairment (MCI). A safe alternative of IV insulin is intranasal (IN) insulin. The aim of this systematic review is to investigate the effects of IN insulin on cognitive function of patients with either AD or MCI.

METHODS

A literature search of the electronic databases Medline, Scopus and CENTRAL was performed to identify RCTs investigating the effect of IN insulin administration on cognitive tasks, in patients with AD or MCI.

RESULTS

Seven studies (293 patients) met our inclusion criteria. Most studies showed that verbal memory and especially story recall was improved after IN insulin administration. Sometimes the effect was restricted for apoe4 (-) patients. Intranasal insulin did not affect other cognitive functions. However, there were some positive results in functional status and daily activity. Data suggested that different insulin types and doses may have different effects on different apoe4 groups. In addition, the effects of treatment on Αβ levels differed from study to study. Finally, IN insulin resulted in minor adverse effects.

CONCLUSIONS

Intranasal insulin improved story recall performance of apoe4 (-) patients with AD or MCI. Other cognitive functions were not affected, but there were some positive results in functional status and daily activity. Since IN insulin is a safe intervention, future studies should be conducted with larger doses and after proper selection of patients and insulin types.

Effects of repetitive transcranial magnetic stimulation on improvement of cognition in elderly patients with cognitive impairment: a systematic review and meta-analysis

OBJECTIVE

This systematic review and meta-analysis aimed to examine the effects of repetitive transcranial magnetic stimulation (rTMS) on cognitive function in older patients with cognitive impairment.

METHODS

A literature search was performed for articles published in English using the 10 databases (MEDLINE, EMBASE, PsycINFO, INSPEC, the Cumulative Index to Nursing and Allied Health Literature Plus, AMED, Biological Sciences, ClinicalTrials.gov, the Cochrane Central Register of Controlled Trials and the Cochrane Database of Systematic Reviews) from their inception to May 2016. The primary outcome was cognitive function as measured by the Mini-Mental State Examination or the Alzheimer's Disease Assessment Scale-cognitive subscale.

RESULTS

Seven RCTs were included in the meta-analysis, with a sample of 107 active and 87 sham rTMS. Active rTMS was found to be more effective in improving cognition (Hedges' g = 0.48; 95% confidence interval 0.12 to 0.84).

CONCLUSIONS

High-frequency rTMS showed a benefit on cognition amongst older patients with mild to moderate Alzheimer's disease. rTMS was shown to have great potential as a safe and well-tolerated alternative intervention for cognition. Copyright © 2017 John Wiley & Sons, Ltd.

Extent of Dorsolateral Prefrontal Cortex Plasticity and Its Association With Working Memory in Patients With Alzheimer Disease

IMPORTANCE

The extent of dorsolateral prefrontal cortex (DLPFC) plasticity in Alzheimer disease (AD) and its association with working memory are not known.

OBJECTIVES

To determine whether participants with AD had impaired DLPFC plasticity compared with healthy control participants, to compare working memory between participants with AD and controls, and to determine whether DLPFC plasticity was associated with working memory.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study included 32 participants with AD who were 65 years or older and met diagnostic criteria for dementia due to probable AD with a score of at least 17 on the Mini-Mental State Examination and 16 age-matched control participants. Participants were recruited from a university teaching hospital from May 2013 to October 2016.

MAIN OUTCOMES AND MEASURES

Plasticity of the DLPFC measured as potentiation of cortical-evoked activity using paired associative stimulation (a combination of peripheral nerve electrical stimulation and transcranial magnetic stimulation) combined with electroencephalography. Working memory was assessed with the n-back task (1- and 2-back) and measured using the A' statistic.

RESULTS

Among the 32 participants with AD, 17 were women and 15 were men (mean [SD] age, 76.3 [6.3] years); among the 16 controls, 8 were men and 8 were women (mean [SD] age, 76.4 [5.1] years). Participants with AD had impaired DLPFC plasticity (mean [SD] potentiation, 1.18 [0.25]) compared with controls (mean [SD] potentiation, 1.40 [0.35]; F1,44 = 5.90; P = .02; between-group comparison, Cohen d = 0.77; P = .01). Participants with AD also had impaired performances on the 1-back condition (mean [SD] A' = 0.47 [0.30]) compared with controls (mean [SD] A' = 0.96 [0.01]; Cohen d = 1.86; P < .001), with similar findings for participants with AD on the 2-back condition (mean [SD] A' = 0.29 [0.2]) compared with controls (mean [SD], A' = 0.85 [0.18]; Cohen d = 2.83; P < .001). Plasticity of DLPFC was positively associated with working memory performance on the 1-back A' (parameter estimate B [SE] = 0.32 [0.13]; standardized β = 0.29; P = .02) and 2-back A' (B [SE] = 0.43 [0.15]; β = 0.39; P = .006) across both groups after controlling for age, education, and attention.

CONCLUSIONS AND RELEVANCE

This study demonstrated impaired in vivo DLPFC plasticity in patients with AD. The findings support the use of DLPFC plasticity as a measure of DLPFC function and a potential treatment target to enhance DLPFC function and working memory in patients with AD.

Using transcranial direct current stimulation to treat symptoms in mild cognitive impairment and Alzheimer's disease

Transcranial direct current stimulation (tDCS) has recently been investigated as a potential nonpharmacological treatment for individuals with mild cognitive impairment (MCI) and Alzheimer's disease (AD). A comprehensive literature search was performed on tDCS studies published until March 2017 using MEDLINE, Embase and PsychINFO databases. 12 articles with a total of 202 MCI or AD participants were included. Although ten of the 12 studies demonstrated positive findings with tDCS, two studies reported no effect on cognition. There was a wide range of methodological approaches used and in the cognitive functions measured. The variability in treatment response may be related to the heterogeneity in stimulation parameters including the site of stimulation, and cognitive assessments used. Patient-related factors including individual psychological, biological, and physiological status at the time of stimulation may also influence treatment response. We recommend that more comparative studies using similar patient factors and study parameters are needed in order to better understand the efficacy of tDCS in MCI and AD.

Cortical excitability and neuropsychological functioning in healthy adults

Evidence from clinical populations, such as epilepsy and attention deficit/hyperactivity disorder, suggests a relationship between hyperexcitability and cognitive impairment, but this relationship has not been demonstrated in healthy individuals. Here, we investigate the relationship between cortical excitability and cognitive functioning in healthy adults. Single- and paired-pulse TMS was applied to 20 healthy adults to measure cortical excitability and long-interval intracortical inhibition (LICI). A neuropsychological battery was administered to assess aspects of attention, executive function, and mood. Participants with primarily excitatory responses to the LICI paradigm performed worse on a composite measure of attention and reported more negative mood states than participants with primarily inhibitory responses. Thus, differences in attention and mood among healthy adults are related to differences in cortical excitability as measured by LICI. This is consistent with a role for GABA_B inhibitory circuits in regulating attention and mood, and suggests that individual variability in these domains may reflect variability in cortical excitability. This study demonstrates preliminary evidence that increased cortical excitability is associated with poorer cognition and mood in healthy adults. These findings provide new insight into the presence of cognitive dysfunction in several patient populations with hyperexcitability and support the development of neurostimulation interventions for clinical use.

Repetitive Transcranial Magnetic Stimulation Improved Symptoms of Obsessive-Compulsive Disorders but Not Executive Functions: Results from a Randomized Clinical Trial with Crossover Design and Sham Condition

OBJECTIVE

Whereas there is growing evidence that repetitive transcranial magnetic stimulation (rTMS) favorably impacts on symptoms of obsessive-compulsive disorders (OCD), less is known regarding the influence of rTMS on cognitive performance of patients with OCD. Here, we tested the hypothesis that rTMS has a positive impact both on symptom severity and executive functions in such patients.

METHODS

We assessed 10 patients diagnosed with OCD (mean age: 33.5 years) and treated with a standard medication; they were randomly assigned either to a treatment-first or to a sham-first condition. Symptom severity (experts' ratings) and executive functions (Wisconsin Card Sorting Test) were assessed by independent raters unaware of the patients' group assignments at baseline, after 2 and 4 weeks. After 2 weeks, treatment switched to sham condition, and sham condition switched to treatment condition.

RESULTS

Under treatment but not under sham conditions, symptom severity decreased. Performance on the executive function test increased continuously with every new assessment and was unrelated to rTMS treatment.

CONCLUSION

Whereas the present study confirmed previous research suggesting that rTMS improved symptoms of OCD, rTMS did not improve executive functions to a greater degree than sham treatment. More research is needed to investigate the effect of rTMS on executive functions in patients with OCD.

What can gait tell us about dementia? Review of epidemiological and neuropsychological evidence

BACKGROUND

Cognitive impairment and gait disorders in people over the age of 65 represent major public health issues because of their high frequency, their link to poor outcomes and high costs. Research has demonstrated that these two geriatric syndromes are closely related.

METHODS AND RESULTS

We aim to review the evidence supporting the relationship between gait and cognitive impairment, particularly focusing on epidemiological and neuropsychological studies in patients with Mild cognitive impairment, Alzheimer's disease and Vascular dementia. The review demonstrates that gait and cognition are closely related, but our knowledge of their interrelationship is limited. Emerging evidence shows that gait analysis has the potential to contribute to diagnosis and prognosis of cognitive impairment.

CONCLUSIONS

An integrated approach for evaluating these major geriatric syndromes, based on their close relationship, will not only increase our understanding of cognitive-motor interactions, but most importantly may be used to aid early diagnosis, prognosis and the development of new interventions.

Improved Prefrontal Activity and Chewing Performance as Function of Wearing Denture in Partially Edentulous Elderly Individuals: Functional Near-Infrared Spectroscopy Study

The purpose of this study was to elucidate the effects of wearing a denture on prefrontal activity during chewing performance. We specifically examined that activity in 12 elderly edentulous subjects [63.1±6.1 years old (mean ± SD)] and 12 young healthy controls (22.1±2.3 years old) using functional near-infrared spectroscopy (fNIRS) in order to evaluate the quality of prefrontal functionality during chewing performance under the conditions of wearing a denture and tooth loss, and then compared the findings with those of young healthy controls. fNIRS and electromyography were used simultaneously to detect prefrontal and masticatory muscle activities during chewing, while occlusal force and masticatory score were also examined by use of a food intake questionnaire. A significant increase in prefrontal activity was observed during chewing while wearing a denture, which was accompanied by increased masticatory muscle activity, occlusal force, and masticatory score, as compared with the tooth loss condition. Prefrontal activation during chewing while wearing a denture in the elderly subjects was not much different from that in the young controls. In contrast, tooth loss in the elderly group resulted in marked prefrontal deactivation, accompanied by decreased masticatory muscle activity, occlusal force, and masticatory score, as compared with the young controls. We concluded that intrinsic prefrontal activation during chewing with a denture may prevent prefrontal depression induced by tooth loss in elderly edentulous patients.

Apathy associated with neurocognitive disorders: Recent progress and future directions

INTRODUCTION

Apathy is common in neurocognitive disorders (NCDs) such as Alzheimer's disease and mild cognitive impairment. Although the definition of apathy is inconsistent in the literature, apathy is primarily defined as a loss of motivation and decreased interest in daily activities.

METHODS

The Alzheimer's Association International Society to Advance Alzheimer's Research and Treatment (ISTAART) Neuropsychiatric Syndromes Professional Interest Area (NPS-PIA) Apathy workgroup reviewed the latest research regarding apathy in NCDs.

RESULTS

Progress has recently been made in three areas relevant to apathy: (1) phenomenology, including the use of diagnostic criteria and novel instruments for measurement, (2) neurobiology, including neuroimaging, neuropathological and biomarker correlates, and (3) interventions, including pharmacologic, nonpharmacologic, and noninvasive neuromodulatory approaches.

DISCUSSION

Recent progress confirms that apathy has a significant impact on those with major NCD and those with mild NCDs. As such, it is an important target for research and intervention.