Neuromodulation in the Treatment of Alzheimer's Disease: Current and Emerging Approaches

Multifactorial effects of short duration early exposure low intensity magnetic field stimulation in Streptozotocin induced Alzheimer's disease rat model

Alzheimer's disease (AD) is an approaching, progressive public health crisis which presently lacks an effective treatment. Various non-invasive novel therapies like repetitive transcranial magnetic stimulation have shown potential to improve cognitive performance in AD patients. In the present study, the effect of extremely low intensity magnetic field (MF) stimulation on neurogenesis and cortical electrical activity was explored. Adult Wistar rats were divided into Sham, AD and AD + MF groups. Streptozotocin (STZ) was injected intracerebroventricularly, at a dose of 3 mg/kg body weight for developing AD model. The AD rats were then exposed to MF (17.96 µT) from 8th day of STZ treatment until 15th day, followed by cognitive assessments and electrocortical recording. In brain tissue samples, cresyl violet staining and BrdU immunohistochemistry were done. MF exposure, improved passive avoidance and recognition memory, attenuated neuronal degeneration and enhanced cell proliferation (BrdU positive cells) in comparison to AD rats. It also significantly restores delta wave power from frontal lobe. Our results suggest that early-stage MF exposure could be an asset for AD research and open new avenues in slowing down the progression of Alzheimer's disease.

Alzheimer's Disease and Related Dementias in Muslim Women: Recommendations for Culturally Sensitive Care

Alzheimer's disease and related dementias (ADRD) present significant challenges including cognitive and functional loss, behavioral disruption, emotional distress, and significant financial burden. These stressors are amplified in minority groups, who experience higher rates of ADRD but less frequent and later diagnosis. There is therefore a critical need to identify tangible approaches to culturally informed dementia assessment and care for patients from diverse communities. Muslim patients and particularly Muslim women are among the populations most understudied in the ADRD space. Muslim patients may hold unique religious, spiritual, and cultural beliefs and practices that can impact care-seeking for dementia symptoms, diagnostic accuracy, and treatment uptake. This paper outlines culturally informed approaches to assessing and treating Muslim women and families at each stage of ADRD care, though many recommendations extend to the broader Muslim community and others of diverse racial-ethnic backgrounds. We provide concrete suggestions for building rapport within and leveraging common family structures, respecting principles of modesty and privacy for all women including those who observe hijab or niqab, and communicating dementia diagnosis and care in the context of spiritual and ethical beliefs. While not intended as a comprehensive and prescriptive guide, this review provides important points of consideration and discussion with patients of Muslim backgrounds.

Functional material-mediated wireless physical stimulation for neuro-modulation and regeneration

Nerve injuries and neurological diseases remain intractable clinical challenges. Despite the advantages of stem cell therapy in treating neurological disorders, uncontrollable cell fates and loss of cell function in vivo are still challenging. Recently, increasing attention has been given to the roles of external physical signals, such as electricity and ultrasound, in regulating stem cell fate as well as activating or inhibiting neuronal activity, which provides new insights for the treatment of neurological disorders. However, direct physical stimulations in vivo are short in accuracy and safety. Functional materials that can absorb energy from a specific physical field exerted in a wireless way and then release another localized physical signal hold great advantages in mediating noninvasive or minimally invasive accurate indirect physical stimulations to promote the therapeutic effect on neurological disorders. In this review, the mechanism by which various physical signals regulate stem cell fate and neuronal activity is summarized. Based on these concepts, the approaches of using functional materials to mediate indirect wireless physical stimulation for neuro-modulation and regeneration are systematically reviewed. We expect that this review will contribute to developing wireless platforms for neural stimulation as an assistance for the treatment of neurological diseases and injuries.

[Non-pharmacological interventions for people with dementia]

BACKGROUND

Non-pharmacological interventions for people with dementia are intended to improve quality of life and well-being, alleviate psychopathological and behavioral symptoms, and also offer caregivers support and opportunities to promote resilience. Against the background of the multiple failures in the field of pharmacological-therapeutic research, these approaches have become increasingly important.

OBJECTIVE

An up-to-date overview of the most important non-drug interventions for people with dementia and related recommendations for therapeutic use.

MATERIAL AND METHODS

Narrative review taking into account the current state of research and the recommendations of the Working Group of (German) Scientific Medical Societies (Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften, AWMF) S3 guideline "Dementia".

RESULTS AND CONCLUSIONS

The most important interventions from this therapeutic spectrum include cognitive stimulation to maintain cognitive functioning, physical activation and creative therapeutic activities to promote communication skills and social participation. In the meantime, access to these diverse psychosocial interventions has also been supplemented by digital technology. What these interventions have in common is that they are based on the individual cognitive and physical resources of those affected, improve quality of life and mood, and promote participation and self-efficacy. In addition to psychosocial interventions, nutrition-related approaches ("medical food") and non-invasive neurostimulation have recently also shown potential in the context of non-drug therapy for people with dementia.

Connectomic neuromodulation for Alzheimer's disease: A systematic review and meta-analysis of invasive and non-invasive techniques

Deep brain stimulation (DBS) and non-invasive neuromodulation are currently being investigated for treating network dysfunction in Alzheimer's Disease (AD). However, due to heterogeneity in techniques and targets, the cognitive outcome and brain network connectivity remain unknown. We performed a systematic review, meta-analysis, and normative functional connectivity to determine the cognitive outcome and brain networks of DBS and non-invasive neuromodulation in AD. PubMed, Embase, and Web of Science were searched using three concepts: dementia, brain connectome, and brain stimulation, with filters for English, human studies, and publication dates 1980-2021. Additional records from clinicaltrials.gov were added. Inclusion criteria were AD study with DBS or non-invasive neuromodulation and a cognitive outcome. Exclusion criteria were less than 3-months follow-up, severe dementia, and focused ultrasound intervention. Bias was assessed using Centre for Evidence-Based Medicine levels of evidence. We performed meta-analysis, with subgroup analysis based on type and age at neuromodulation. To determine the patterns of neuromodulation-induced brain network activation, we performed normative functional connectivity using rsfMRI of 1000 healthy subjects. Six studies, with 242 AD patients, met inclusion criteria. On fixed-effect meta-analysis, non-invasive neuromodulation favored baseline, with effect size -0.40(95% [CI], -0.73, -0.06, p = 0.02), while that of DBS was 0.11(95% [CI] -0.34, 0.56, p = 0.63), in favor of DBS. In patients ≥65 years old, DBS improved cognitive outcome, 0.95(95% [CI] 0.31, 1.58, p = 0.004), whereas in patients <65 years old baseline was favored, -0.17(95% [CI] -0.93, 0.58, p = 0.65). Functional connectivity regions were in the default mode (DMN), salience (SN), central executive (CEN) networks, and Papez circuit. The subgenual cingulate and anterior limb of internal capsule (ALIC) showed connectivity to all targets of neuromodulation. This meta-analysis provides level II evidence of a difference in response of AD patients to DBS, based on age at intervention. Brain stimulation in AD may modulate DMN, SN, CEN, and Papez circuit, with the subgenual cingulate and ALIC as potential targets.

Effects of Photobiomodulation on Changes in Cognitive Function and Regional Cerebral Blood Flow in Patients with Mild Cognitive Impairment: A Pilot Uncontrolled Trial

BACKGROUND

Photobiomodulation (PBM) affects local blood flow regulation through nitric oxide generation, and various studies have reported on its effect on improving cognitive function in neurodegenerative diseases. However, the effect of PBM in the areas of the vertebral arteries (VA) and internal carotid arteries (ICA), which are the major blood-supplying arteries to the brain, has not been previously investigated.

OBJECTIVE

We aimed to determine whether irradiating PBM in the areas of the VA and ICA, which are the major blood-supplying arteries to the brain, improved regional cerebral blood flow (rCBF) and cognitive function.

METHODS

Fourteen patients with mild cognitive impairments were treated with PBM. Cognitive assessment and single-photon emission computed tomography were implemented at the baseline and at the end of PBM.

RESULTS

Regarding rCBF, statistically significant trends were found in the medial prefrontal cortex, lateral prefrontal cortex, anterior cingulate cortex, and occipital lateral cortex. Based on the cognitive assessments, statistically significant trends were found in overall cognitive function, memory, and frontal/executive function.

CONCLUSION

We confirmed the possibility that PBM treatment in the VA and ICA areas could positively affect cognitive function by increasing rCBF. A study with a larger sample size is needed to validate the potential of PBM.

An Effective and Safe Novel Treatment of Opioid Use Disorder: Unilateral Transcranial Photobiomodulation

Background: The opioid epidemic is a global tragedy even with current treatments, and a novel, safe, and effective treatment would be welcomed. We report here our findings from our second randomized controlled trial to evaluate unilateral transcranial photobiomodulation as a treatment for opioid use disorder. Methods: We enrolled 39 participants with active opioid cravings at 2 sites, 19 received the active treatment which consisted of a 4-min twice weekly (every 3 or 4 days) application of a light-emitting diode at 810 nm with an irradiance of 250 mW/cm2 and a fluence of 60 J/cm2 to the forehead over either the left or right dorsolateral prefrontal cortex with a fluence to the brain of 2.1 J/cm2. Twenty participants received a sham treatment with the same device with foil over the bulb. The side of the treatment was based on Dual-Brain Psychology, which posits that one hemisphere is more affected by past maltreatments and is more prone to anxiety and drug cravings that the other hemisphere. We treated the hemisphere with the more positive hemispheric emotional valence (HEV) by 2 tests for HEV. Results: Our primary outcome was changes in pre-treatment opioid craving scale (OCS) minus baseline, and we found using a mixed model that the active group had a highly significant treatment * time benefit over the sham group, p < 0.0001, effect size at the last follow-up of 1.5. The active treatment benefited those not on buprenorphine as well as those not on it. The TimeLine Follow Back measure of opioid use was significantly better in the actively treated group, p = 0.0001, with an effect size of 0.45. We observed no adverse effects. Conclusion: Active unilateral transcranial photobiomodulation to the brain hemisphere with the better HEV was better than sham in the reduction of opioid cravings and opioid use to a very significant degree in a RCT of 39 participants at 2 independent sites. In the active group those on buprenorphine and those not on it both had improvements in cravings over the study. No adverse responses were reported in either group. ClinicalTrials.gov Identifier: NCT04340622.

Repetitive transcranial magnetic stimulation increases the brain's drainage efficiency in a mouse model of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease with high prevalence rate among the elderly population. A large number of clinical studies have suggested repetitive transcranial magnetic stimulation (rTMS) as a promising non-invasive treatment for patients with mild to moderate AD. However, the underlying cellular and molecular mechanisms remain largely uninvestigated. In the current study, we examined the effect of high frequency rTMS treatment on the cognitive functions and pathological changes in the brains of 4- to 5-month old 5xFAD mice, an early pathological stage with pronounced amyloidopathy and cognitive deficit. Our results showed that rTMS treatment effectively prevented the decline of long-term memories of the 5xFAD mice for novel objects and locations. Importantly, rTMS treatment significantly increased the drainage efficiency of brain clearance pathways, including the glymphatic system in brain parenchyma and the meningeal lymphatics, in the 5xFAD mouse model. Significant reduction of Aβ deposits, suppression of microglia and astrocyte activation, and prevention of decline of neuronal activity as indicated by the elevated c-FOS expression, were observed in the prefrontal cortex and hippocampus of the rTMS-treated 5xFAD mice. Collectively, these findings provide a novel mechanistic insight of rTMS in regulating brain drainage system and β-amyloid clearance in the 5xFAD mouse model, and suggest the potential use of the clearance rate of contrast tracer in cerebrospinal fluid as a prognostic biomarker for the effectiveness of rTMS treatment in AD patients.