Challenges to and Facilitators of Recruitment to an Alzheimer's Disease Clinical Trial: A Qualitative Interview Study

A "Patient Preference" Model of Recruitment for Research from Primary-Care-Based Memory Clinics: A Promising New Approach

Recruiting persons with dementia for clinical trials can be challenging. Building on a guide initially developed to assist primary-care-based memory clinics in their efforts to support research, a key stakeholder working group meeting was held to develop a standardized research recruitment process, with input from patients, care partners, researchers, and clinicians. Discussions in this half-day facilitated meeting focused on the wishes and needs of patients and care partners, policy and procedures for researchers, information provided to patients, and considerations for memory clinics. Patients and care partners valued the opportunity to contribute to science and provided important insights on how to best facilitate recruitment. Discussions regarding proposed processes and procedures for research recruitment highlighted the need for a new, patient-driven approach. Accordingly, a key stakeholder co-designed "Memory Clinic Research Match" program was developed that has the potential to overcome existing barriers and to increase recruitment for dementia-related research.

Radiation Therapy in Alzheimer's Disease: A Systematic Review

PURPOSE

Pathophysiological hallmarks of Alzheimer's disease (AD) include extracellular amyloid plaques and intracellular neurofibrillary tangles. Recent studies also demonstrated a role of neuroinflammation in the progression of the disease. Clinical trials and animal studies using low-dose radiation therapy (LDRT) have shown therapeutic potential for AD. This systematic review summarizes the current evidence on the use of LDRT for the treatment of AD, outlines potential mechanisms of action, and discusses current challenges in the planning of future trials.

METHODS AND MATERIALS

A systematic review of human and animal studies as well as registered clinical trials describing outcomes for RT in the treatment of AD was conducted. We followed the 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Articles published until July 1, 2023, were included.

RESULTS

The initial search yielded 993 articles. After the removal of duplicates and ineligible publications, a total of 16 (12 animal, 4 human) studies were included. Various dose regimens were utilized in both animal and human trials. The results revealed that LDRT reduced the number of amyloid plaques and neurofibrillary tangles, and it has a role in the regulation of genes and protein expression involved in the pathological progression of AD. LDRT has demonstrated reduced astro- and microgliosis, anti-inflammatory and neuroprotective effects, and an alleviation of symptoms of cognitive deficits in animal models. Most studies in humans suggested improvements in cognition and behavior. None of the trials or studies described significant (>grade 2) toxicity.

CONCLUSIONS

Preclinical studies, animal studies, and early clinical trials in humans have shown a promising role for LDRT in the treatment of AD pathologies, although the underlying mechanisms are yet to be fully explored. Phase I/II/III trials are needed to assess the long-term safety, efficacy, and optimal treatment parameters of LDRT in AD treatment.

Barriers to Alzheimer Disease Clinical Trial Participation in a Minority Population

BACKGROUND

Alzheimer disease (AD), the most common neurodegenerative disorder in the United States, disproportionately burdens minority populations.

OBJECTIVE

To explore barriers to AD clinical trial participation by Asian and Native Hawaiian patients diagnosed with AD or mild cognitive impairment.

METHOD

We surveyed 187 patients with a Mini-Mental State Examination score ≥14 between January 2022 and June 2022. The score cutoff for clinical trial eligibility was set by the institution. Individuals also completed a 15-question telephone survey that assessed demographics, barriers to clinical trial participation, and clinical trial improvement methods.

RESULTS

Forty-nine patients responded, with a response rate of 26%. Asian and Native Hawaiian patients were less likely than White patients to participate in AD trials. The main barrier to participation was a lack of information about AD trials. Providing additional information regarding AD trials to patients and family members were listed as the top two reasons patients would consider participating in a clinical trial.

CONCLUSION

Insufficient information about AD clinical trials is the primary barrier to participation among Asian and Native Hawaiian patients, followed by difficulty coordinating transportation and, in the case of Asians, the time required for clinical trials. Increased outreach, education, and assistance with logistics in these populations should be pursued to improve rates of participation in clinical trials.

Recruitment of pre-dementia participants: main enrollment barriers in a longitudinal amyloid-PET study

BACKGROUND

The mismatch between the limited availability versus the high demand of participants who are in the pre-dementia phase of Alzheimer's disease (AD) is a bottleneck for clinical studies in AD. Nevertheless, potential enrollment barriers in the pre-dementia population are relatively under-reported. In a large European longitudinal biomarker study (the AMYPAD-PNHS), we investigated main enrollment barriers in individuals with no or mild symptoms recruited from research and clinical parent cohorts (PCs) of ongoing observational studies.

METHODS

Logistic regression was used to predict study refusal based on sex, age, education, global cognition (MMSE), family history of dementia, and number of prior study visits. Study refusal rates and categorized enrollment barriers were compared between PCs using chi-squared tests.

RESULTS

535/1856 (28.8%) of the participants recruited from ongoing studies declined participation in the AMYPAD-PNHS. Only for participants recruited from clinical PCs (n = 243), a higher MMSE-score (β =  - 0.22, OR = 0.80, p < .05), more prior study visits (β =  - 0.93, OR = 0.40, p < .001), and positive family history of dementia (β = 2.08, OR = 8.02, p < .01) resulted in lower odds on study refusal. General study burden was the main enrollment barrier (36.1%), followed by amyloid-PET related burden (PCresearch = 27.4%, PCclinical = 9.0%, X2 = 10.56, p = .001), and loss of research interest (PCclinical = 46.3%, PCresearch = 16.5%, X2 = 32.34, p < .001).

CONCLUSIONS

The enrollment rate for the AMYPAD-PNHS was relatively high, suggesting an advantage of recruitment via ongoing studies. In this observational cohort, study burden reduction and tailored strategies may potentially improve participant enrollment into trial readiness cohorts such as for phase-3 early anti-amyloid intervention trials. The AMYPAD-PNHS (EudraCT: 2018-002277-22) was approved by the ethical review board of the VU Medical Center (VUmc) as the Sponsor site and in every affiliated site.

Digital health technologies and Alzheimer's disease clinical trials: might decentralized clinical trials increase participation by people with cognitive impairment?

BACKGROUND

Therapeutic trials in Alzheimer's disease (AD) face many obstacles-particularly with regard to screening and recruitment.

DISCUSSION

Decentralized clinical trials (DCTs) are being developed in other diseases and appear to be of value for overcoming these difficulties. The use of remote visits offers hope of broader recruitment and thus a reduction in inequalities due to age, geography, and ethnicity. Furthermore, it might be easier to involve primary care providers and caregivers in DCTs. However, further studies are needed to determine the feasibility of DCTs in AD. A mixed-model DCT might constitute the first step towards completely remote trials in AD and should be assessed first.

Experiences of and recommendations on clinical trial design in Alzheimer's disease from the participant's point of view: a mixed-methods study in two clinical trial centers in the Netherlands

INTRODUCTION

In the context of the development of pharmaceutical interventions, expectations and experiences of participants are essential. Their insights may be particularly helpful to address the challenges of recruiting and retaining participants for Alzheimer's disease (AD) clinical trials. We examined clinical trial participants' experiences to optimize trial design in Alzheimer's disease (AD).

METHOD

In this mixed-methods study, we included adults who participated in sponsor-initiated AD trials at Brain Research Center, a clinical trial organization in the Netherlands. Participants (N = 71, age 69 ± 6.5, 54%F, 19 cognitively normal (CN), 19 mild cognitive impairment (MCI), and 33 AD dementia) first completed an online survey. Diagnostic group differences were investigated using chi-square tests or one-way ANOVAs. Next, a subsample (N = 12; 8 = CN, 4 = MCI) participated in focus groups to gain in-depth insight into their opinions on optimizing trial design from a participants' point of view. Audio recordings from focus group interviews were transcribed verbatim and analyzed by thematic content analysis by two independent researchers.

RESULTS

Most reported motives for enrolment included "to benefit future generations" (89%), followed by "for science" (66%) and "better monitoring" (42%). Frequent suggestions for increasing willingness to participate included a smaller chance to receive placebo (n = 38, 54%), shorter travel times (n = 27, 38%), and sharing individual results of different assessments (n = 57, 80%), as well as receiving trial results (n = 52, 73). Highest visual analogue burden scores (0-100) were found for the lumbar puncture (M = 47.2, SD = 38.2) and cognitive assessments (M = 27.2, SD = 25.7). Results did not differ between diagnostic groups, nor between patient and caregiver participants (all p-values>.05). Two additional themes emerged from the focus groups: "trial design," such as follow-up visit(s) after participating, and "trial center," including the relevance of a professional and empathic staff.

CONCLUSION

Relevant factors include expectation management and careful planning of high-burden assessments, provision of individual feedback, and prioritizing professionalism and empathy throughout conduct of the trial. Our findings provide insight into participants' priorities to increase willingness to participate and can be used to optimize trial success.

Challenges for machine learning in clinical translation of big data imaging studies

Combining deep learning image analysis methods and large-scale imaging datasets offers many opportunities to neuroscience imaging and epidemiology. However, despite these opportunities and the success of deep learning when applied to a range of neuroimaging tasks and domains, significant barriers continue to limit the impact of large-scale datasets and analysis tools. Here, we examine the main challenges and the approaches that have been explored to overcome them. We focus on issues relating to data availability, interpretability, evaluation, and logistical challenges and discuss the problems that still need to be tackled to enable the success of "big data" deep learning approaches beyond research.

Understanding the perspectives of recruiters is key to improving randomised controlled trial enrolment: a qualitative evidence synthesis

Background

Recruiting patients to randomised controlled trials (RCTs) is often reported to be challenging, and the evidence base for effective interventions that could be used by staff (recruiters) undertaking recruitment is lacking. Although the experiences and perspectives of recruiters have been widely reported, an evidence synthesis is required in order to inform the development of future interventions. This paper aims to address this by systematically searching and synthesising the evidence on recruiters’ perspectives and experiences of recruiting patients into RCTs. 

Methods

A qualitative evidence synthesis (QES) following Thomas and Harden’s approach to thematic synthesis was conducted. The Ovid MEDLINE, CINAHL, EMBASE, PsycInfo, Cochrane Central Register of Controlled Trials, ORRCA and Web of Science electronic databases were searched. Studies were sampled to ensure that the focus of the research was aligned with the phenomena of interest of the QES, their methodological relevance to the QES question, and to include variation across the clinical areas of the studies. The GRADE CERQual framework was used to assess confidence in the review findings.

Results

In total, 9316 studies were identified for screening, which resulted in 128 eligible papers. The application of the QES sampling strategy resulted in 30 papers being included in the final analysis. Five overlapping themes were identified which highlighted the complex manner in which recruiters experience RCT recruitment: (1) recruiting to RCTs in a clinical environment, (2) enthusiasm for the RCT, (3) making judgements about whether to approach a patient, (4) communication challenges, (5) interplay between recruiter and professional roles.

Conclusions

This QES identified factors which contribute to the complexities that recruiters can face in day-to-day clinical settings, and the influence recruiters and non-recruiting healthcare professionals have on opportunities afforded to patients for RCT participation. It has reinforced the importance of considering the clinical setting in its entirety when planning future RCTs and indicated the need to better normalise and support research if it is to become part of day-to-day practice.

Trial registration

PROSPERO CRD42020141297 (registered 11/02/2020).

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06818-4.

Recruitment of Older Adults With Dementia for Research: An Integrative Review

Recruitment of persons with dementia into research studies is essential to provide evidence for effective care and treatment. However, recruitment is known to be difficult for this population. The current integrative review was undertaken to synthesize evidence surrounding best practices for recruiting older adults with dementia into research. Fourteen studies were identified that examined recruitment strategies for persons with cognitive impairment over a 10-year time period. Most studies were retrospective and descriptive. Studies revealed three facilitators and three barriers for recruitment. Facilitators included community partnerships and trust, incentives, and use of multiple recruitment methods. Barriers included non-targeted recruitment methods, gatekeepers, and mistrust. Further studies, including randomized controlled trials, are needed to determine specific strategies that yield effective recruitment. Theoretically based recruitment strategies need to be defined and tested and the measures of recruitment efforts standardized to compare effectiveness and build a science of recruitment. [Research in Gerontological Nursing, 15(5), 255-264.].

The role of massive demographic databases in intractable illnesses: Denomics for dementia

Despite intensive research, effective treatments for many common and devastating diseases are lacking. For example, huge efforts and billions of dollars have been invested in Alzheimer's disease (AD), which affects over 50 million people worldwide. However, there is still no effective drug that can slow or cure AD. This relates, in part, to the absence of an animal model or cellular system that incorporates all the relevant features of the disease. Therefore, large scale studies on human populations and tissues will be key to better understanding dementia and developing methods to prevent or treat it. This is especially difficult because the dementia phenotype can result from many different processes and is likely to be affected by multiple personal and environmental variables. We hypothesize that analyzing massive volumes of demographic data that are currently available and combining this with genomic, proteomic, and metabolomic profiles of AD patients and their families, new insights into pathophysiology and treatment of AD may arise. While this requires much coordination and cooperation among large institutions, the potential for advancement would be life-changing for millions of people. In many ways this represents the next step in the information revolution started by the Human Genome Project.

A four-month home-based tDCS study on patients with Alzheimer's disease

In the present open-label study, our first aim was to study the tolerability and feasibility of long-term treatment with transcranial direct current stimulation (tDCS) and the second aim was to measure whether the treatment led to cognitive improvement. Participants with AD used a tDCS home-treatment kit inducing a low current (2 mA) via two scalp electrodes 30 minutes daily for 4 months. A total of 8 participants were recruited. The treatment technique was manageable for the participants and their spouses, and no troublesome side effects were reported. No significant effects of treatment were found after 4 months.

Success and failure factors of patient recruitment for industry-sponsored clinical trials and the role of the electronic health records-a qualitative interview study in the Nordic countries

Background

Patient recruitment for clinical trials is challenging—only approximately one third of all trials recruit their participants as planned. The pharmaceutical industry’s views on recruitment success have not been comprehensively investigated, although the industry globally conducts almost one third of all clinical drug trials. This study explored patient recruitment success and failure factors and the role of electronic health records (EHR) in the recruitment of trial participants in the Nordic countries.

Methods

A descriptive qualitative interview study was conducted with 21 representatives of the pharmaceutical industry or contract research organizations operating in Finland, Sweden, Denmark, and Norway. The interviews covered 34 clinical pre-market drug trials. Qualitative data were analyzed using inductive content analysis.

Results

Four main categories were derived to represent both success and failure factors, whereas a fifth category represented only failure factors: (1) sponsor-related (protocol and trial preparation and feasibility evaluations), (2) site/investigator-related (access to patients, motivation, commitment and resources), (3) patient-related recruitment factors (medical need, patients’ role in their care and attitudes towards trials), (4) Sponsor—sites—patients collaboration factors, and (5) start-up related factors. EHR was the most important source of recruitment, utilized in 29 out of 34 trials discussed. Revision of the legislation regulating the secondary use of EHR was highlighted as the most effective measure to facilitate the use of EHR in recruitment of trial participants.

Conclusions

The industry representatives recognized quite well their own role in contributing to the success or failure of the recruitment: to facilitate recruitment of trial participants, many obstacles can be avoided with better trial preparation and proper feasibility evaluations. As access to patients represents one of the key success or failure factors of recruitment, and as the EHR is regarded the main source of searching for and finding patients, the development of EHR utilization appears to represent a powerful tool to improve patient recruitment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06144-9.

Predictors of Willingness to Enroll in Hypothetical Alzheimer Disease Biomarker Studies that Disclose Personal Results

INTRODUCTION

We examined factors related to willingness to enroll in hypothetical Alzheimer disease (AD) biomarker studies.

METHODS

Using linear regression, we assessed the relationship among enrollment willingness and demographics, family dementia history, research attitudes, concern about AD, experiences of discrimination, and belief in AD risk modifiability. Inductive coding was used to assess qualitative data.

RESULTS

In middle-aged and older adult AD research participants (n=334), willingness to enroll in biomarker studies was driven by biomarker collection method, research attitudes, and disclosure of personal results. Predictors of willingness were similar for Black and White participants. Themes associated with increased willingness included a desire to learn biomarker results and support research.

DISCUSSION

Research attitudes were an important predictor of biomarker study willingness regardless of race. As seen elsewhere, Black participants were more hesitant to participate in biomarker research. Disclosure of biomarker results/risk can bolster willingness to enroll in biomarker studies, particularly for Black participants.

The role of Memory Clinics in the assessment and management of dementia, now and into the future

PURPOSE OF REVIEW

The diagnosis of dementia is often delayed and many individuals with the disorder go undiagnosed or receive an inadequate assessment. Specialist Memory Clinics have long been at the centre of such assessments. Recent developments in biomarkers and disease-modifying treatments are likely increase the need for specialist assessments. It is therefore timely to review the role of Memory Clinics internationally.

RECENT FINDINGS

The timely diagnosis of dementia and cognitive decline is the main responsibility of Memory Clinics. These clinics can diagnose dementia up to 4 years earlier than primary care services, but their low numbers and capacity of leads to long waiting times and a focus on complex cases. Few clinics are resourced to offer specific postdiagnostic support services, and their roles in clinical trials and research have not been realised. They are often well integrated with primary care and aged care services.

SUMMARY

Memory Clinics play an important role in bridging the gap between research and clinical practice and providing high-quality assessment and care. Additional Memory Clinic services and greater harmonisation of their responsibilities and procedures are needed to exploit their full potential.

Neural correlates of dual-task walking in people with central neurological disorders: a systematic review

BACKGROUND

People with central neurological disorders experience difficulties with dual-task walking due to disease-related impairments. The objective of this review was to provide a comprehensive examination of the neural correlates (structural/functional brain changes) of dual-task walking in people with Parkinson's disease (PD), multiple sclerosis (MS), stroke, and Alzheimer's disease (AD).

METHODS

A systematic review of the literature was conducted, following PRISMA guidelines, on Medline, Embase, and Scopus. Included studies examined the relationship between structural and functional brain imaging and dual-task walking performance in people with PD, MS, stroke, and AD. Articles that met the inclusion criteria had baseline characteristics, study design, and behavioral and brain outcomes extracted. Twenty-three studies were included in this review.

RESULTS

Most structural imaging studies (75%) found an association between decreased brain integrity and poor dual-task performance. Specific brain regions that showed this association include the striatum regions and hippocampus in PD and supplementary motor area in MS. Functional imaging studies reported an association between increased prefrontal activity and maintained (compensatory recruitment) or decreased dual-task walking performance in PD and stroke. A subset (n = 2) of the stroke papers found no significant correlations. Increased supplementary motor area activity was associated with decreased performance in MS and stroke. No studies on AD were identified.

CONCLUSION

In people with PD, MS, and stroke, several neural correlates of dual-task walking have been identified, however, the direction of the association between neural and performance outcomes varied across the studies. The type of cognitive task used and presentation modality (e.g., visual) may have contributed to these mixed findings.

Experiences of Participation in a Multimodal Preventive Trial MIND-ADMINI Among Persons with Prodromal Alzheimer’s Disease: A Qualitative Study

Introduction

Alzheimer’s disease (AD) is one of the world’s leading public health challenges. One-third of AD cases are attributable to modifiable vascular and lifestyle-related risk factors. The Multimodal Preventive Trial for Alzheimer’s Disease, MIND-AD_MINI a 6-month multinational parallel-group randomized controlled trial (RCT), targeted persons with prodromal AD and built on the positive outcomes from the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) trial. The intervention consisted of four main components of (i) physical exercise training program, (ii) nutrition guidance, (iii) cognitive training, and (iv) social stimulation, as well as (iv) monitoring of metabolic/vascular risk factors.

Aim

The study aimed to explore and describe the experiences of participation in MIND-AD_MINI among persons with prodromal AD.

Methods

This qualitative study was part of the larger MIND-AD_MINI project. Eight participants were interviewed twice, before and after the intervention. The data was analyzed using qualitative content analysis.

Results

The results are presented as categories of (i) knowledge of AD and prevention, (ii) motives for study participation, (iii) experiences of the received information about the study, (iv) taking the decision to participate, (v) expectations on study participation, (vi) experiences of study participation and (vii) internal and external factors influencing study participation.

Conclusion

The MIND-AD_MINI was well-tolerated by the participants. At the beginning of the study, the number of tasks and visits was perceived as burdensome but was later well-tolerated. The participant’ knowledge about AD and prevention increased during the trial. Their motives for participating in MIND-AD_MINI were described as both altruistic and self-beneficial. Health benefits from the study components, access to specialized medical care were identified as benefits. Managing the intensive flow of information was described a major challenge. The participants’ needs for personalized support during the trial stress the importance of applying a person-centered approach providing the preventive trials.

Safety and efficacy of losartan for the reduction of brain atrophy in clinically diagnosed Alzheimer's disease (the RADAR trial): a double-blind, randomised, placebo-controlled, phase 2 trial

Background

Drugs modifying angiotensin II signalling could reduce Alzheimer's disease pathology, thus decreasing the rate of disease progression. We investigated whether the angiotensin II receptor antagonist losartan, compared with placebo, could reduce brain volume loss, as a measure of disease progression, in clinically diagnosed mild-to-moderate Alzheimer's disease.

Methods

In this double-blind, multicentre, randomised controlled trial, eligible patients aged 55 years or older, previously untreated with angiotensin II drugs and diagnosed (National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association criteria) with mild-to-moderate Alzheimer's disease, and who had capacity to consent, were recruited from 23 UK National Health Service hospital trusts. After undergoing a 4-week, open-label phase of active treatment then washout, participants were randomly assigned (1:1) oral over-encapsulated preparations of either 100 mg losartan (after an initial two-dose titration stage) or matched placebo daily for 12 months. Randomisation, minimised by age and baseline medial temporal lobe atrophy score, was undertaken online or via pin-access service by telephone. Participants, their study companions, and study personnel were masked to group assignment. The primary outcome, analysed by the intention-to-treat principle (ie, participants analysed in the group to which they were randomised, without imputation for missing data), was change in whole brain volume between baseline and 12 months, measured using volumetric MRI and determined by boundary shift interval (BSI) analysis. The trial is registered with the International Standard Randomised Controlled Trial Register (ISRCTN93682878) and the European Union Drug Regulating Authorities Clinical Trials Database (EudraCT 2012–003641–15), and is completed.

Findings

Between July 22, 2014, and May 17, 2018, 261 participants entered the open-label phase. 211 were randomly assigned losartan (n=105) or placebo (n=106). Of 197 (93%) participants who completed the study, 171 (81%) had complete primary outcome data. The mean brain volume (BSI) reduction was 19·1 mL (SD 10·3) in the losartan group and 20·0 mL (10·8) in the placebo group. The difference in total volume reduction between groups was –2·29 mL (95% CI –6·46 to 0·89; p=0·14). The number of adverse events was low (22 in the losartan group and 20 in the placebo group) with no differences between treatment groups. There was one treatment-related death per treatment group.

Interpretation

12 months of treatment with losartan was well tolerated but was not effective in reducing the rate of brain atrophy in individuals with clinically diagnosed mild-to-moderate Alzheimer's disease. Further research is needed to assess the potential therapeutic benefit from earlier treatment in patients with milder cognitive impairment or from longer treatment periods.

Funding

Efficacy and Mechanism Evaluation Programme (UK Medical Research Council and National Institute for Health Research).

Predicting future amyloid biomarkers in dementia patients with machine learning to improve clinical trial patient selection

INTRODUCTION

In Alzheimer's disease, asymptomatic patients may have amyloid deposition, but predicting their progression rate remains a substantial challenge with implications for clinical trial enrollment. Here, we demonstrate an artificial intelligence approach to use baseline clinical information and images to predict changes in quantitative biomarkers of brain pathology on future images.

METHODS

Patients from the Alzheimer's Disease Neuroimaging Initiative (ADNI) who underwent positron emission tomography (PET) with the amyloid radiotracer 18F-AV45 (florbetapir) were included. We identified important baseline PET image features using a deep convolutional neural network based on ResNet. These were combined with eight clinical, demographic, and genetic markers using a gradient-boosted decision tree (GBDT) algorithm to predict future quantitative standardized uptake value ratio (SUVR), an established biomarker of brain amyloid deposition. We used this model to better identify individuals with the highest positive change in amyloid deposition on future images and compared this to typical inclusion criteria for clinical trials. We also compared the model's performance to other methods such as multivariate linear regression and GBDT without imaging features.

FINDINGS

Using 2577 PET scans from 1224 unique individuals, we showed that the GBDT with deep image features was significantly more accurate than the other approaches, reaching a root mean squared error of 0.0339 ± 0.0027 for future SUVR prediction. Using this approach, we could identify individuals with the highest 10% SUVR accumulation at rates 2- to 4-fold higher than by random pick or existing inclusion criteria.

DISCUSSION

Predicting quantitative biomarkers on future images using machine learning methods consisting of deep image features combined with clinical data may allow better targeting of treatments or enrollment in clinical trials.

High-Definition Transcranial Direct Current Stimulation Improves Delayed Memory in Alzheimer's Disease Patients: A Pilot Study Using Computational Modeling to Optimize Electrode Position

BACKGROUND

The optimal stimulation parameters when using transcranial direct current stimulation (tDCS) to improve memory performance in patients with Alzheimer's disease (AD) are lacking. In healthy individuals, inter-individual differences in brain anatomy significantly influence current distribution during tDCS, an effect that might be aggravated by variations in cortical atrophy in AD patients.

OBJECTIVE

To measure the effect of individualized HD-tDCS in AD patients.

METHODS

Nineteen AD patients were randomly assigned to receive active or sham high-definition tDCS (HD-tDCS). Computational modeling of the HD-tDCS-induced electric field in each patient's brain was analyzed based on magnetic resonance imaging (MRI) scans. The chosen montage provided the highest net anodal electric field in the left dorsolateral prefrontal cortex (DLPFC). An accelerated HD-tDCS design was conducted (2 mA for 3×20 min) on two separate days. Pre- and post-intervention cognitive tests and T1 and T2-weighted MRI and diffusion tensor imaging data at baseline were analyzed.

RESULTS

Different montages were optimal for individual patients. The active HD-tDCS group improved significantly in delayed memory and MMSE performance compared to the sham group. Five participants in the active group had higher scores on delayed memory post HD-tDCS, four remained stable and one declined. The active HD-tDCS group had a significant positive correlation between fractional anisotropy in the anterior thalamic radiation and delayed memory score.

CONCLUSION

HD-tDCS significantly improved delayed memory in AD. Our study can be regarded as a proof-of-concept attempt to increase tDCS efficacy. The present findings should be confirmed in larger samples.

Recruiting Persons with Dementia and Caregivers in a Clinical Trial: Dyads Perceptions

Recruitment for dementia research is challenging and costly. Using Ajzen's Theory of Planned Behavior we explored attitudes, perceived norms, and perceived behavioral control of persons living with dementia (PLWD) and their caregivers who participated in one clinical trial to better understand factors that influence dyads' decisions to enroll. We conducted semi-structured telephone interviews with 12 PLWD and 9 caregivers and utilized directed content analysis. Categories connected with positive attitudes about study enrollment were personal desires of wanting to learn and in-person meetings with knowledgeable staff. Additionally, participants said the money always helps in terms of the financial incentive. Participants reported enrolling to support another person (perceived norm). Study requirements were thought to be easy (perceived behavioral control). Participants highlighted the importance of flexible scheduling and study tasks being completed at their home. Findings can inform future recruitment efforts and should be investigated as effective recruitment methods in other clinical trials.

Modifiable Barriers for Recruitment and Retention of Older Adults Participants from Underrepresented Minorities in Alzheimer's Disease Research

Clinical Alzheimer's disease (AD) trials currently face a critical shortfall of thousands of eligible participants, which inflates the duration and cost of the clinical study as well as threatens the scientific merit of promising clinical interventions. This recruitment crisis is further compounded by the fact that underrepresented and marginalized populations-particularly those identifying as a racial or ethnic minority, those with low socioeconomic status, or living in rural areas-have been historically underrepresented in ongoing AD clinical trials despite overwhelming evidence that such populations are at increased risk for developing dementia. As a result of various recruitment barriers, current AD clinical studies frequently reflect a decreasingly representative segment of the US population, which threatens the overall generalizability of these findings. The current narrative review provides an updated examination and critique of common recruitment barriers and potential solutions, as well as a discussion of theoretical approaches that may address barriers disproportionately experienced by underrepresented communities. AD clinical researchers are encouraged to take purposive action aimed at increasing diversity of enrolled AD clinical trial cohorts by actively identifying and quantifying barriers to research participation-especially recruitment barriers and health disparities that disproportionately prevent underrepresented and marginalized populations from participating in research. Furthermore, researchers are encouraged to closely track which individuals who express interest in AD research ultimately enroll in research studies to examine whether AD research participation is appropriately representative of the intended population for whom these new and novel AD interventions are being designed.