Introduction
Dementia is defined as a decline in cognitive function that is severe enough to affect daily life and activities. Early-onset dementia (EOD) specifically refers to dementia that occurs before the age of 65. As stated by the World Health Organization, around 5-10% of all dementia cases are classified as early onset. Symptoms of EOD often include memory loss, difficulties with problem-solving or language, disorientation, and changes in mood or behavior. These symptoms can vary significantly depending on the underlying cause of dementia, which may include Alzheimer’s disease, frontotemporal dementia, or vascular dementia.
Bibliometric analysis is a valuable tool for examining research trends in any field. It allows for a comprehensive investigation of leaders and new ideas in the field and the overall research status, providing a thorough approach to the analysis of published studies.1 This approach has rapidly developed in the last decades and is extensively used in various domains, including medicine and biology.2 By analyzing and visualizing research literature through tools like VOSviewer, bibliometric analysis can reveal trends and insights that assist future researchers in quickly understanding the new progress and focus areas within a field.3
Recently, the number of articles focusing on early-onset dementia has increased significantly. This paper utilizes bibliometric analysis to investigate research literature on EOD from 1967 to 2024, collected from Web of Science. The analysis aims to uncover research focal points and developments in the field of early-onset dementia, providing new insights that can guide future research efforts. The results of this analysis will help researchers understand the overall progress and direction of EOD research, fostering continued advancements in understanding and addressing this challenging condition.
Material and Methods
Indicators of evaluation that were used for analysis in this study consist of the quantity of articles published, nations, growth, organizations, authors, and keywords. The primary analysis method used for these articles was association strength using VOSviewer. Without any restrictions on the date of publication, every article that was obtained was from Web of Science. The search term “dementia AND early-onset AND symptoms” was created using boolean operators to narrow down the results. This made it possible to use 2433 publications for the bibliometric analysis.
Results
Countries and Growth
Of the 82 countries and 2433 papers, the USA is the leading producer of papers regarding early onset symptoms of dementia. The top 10 most productive countries in this field are the USA, England, Japan, People’s Republic Of China, France, Spain, Netherlands, Canada, Australia, Italy, Germany, and Sweden. The earliest published papers available on the Web of Science regarding this topic date back to 1967. From 1967 to 1990, there was an average of two papers published annually. However, in 1991, research on early onset symptoms of dementia began to increase significantly. From 1990 to 2024, the average number of papers published per year was approximately 70. This notable increase in research activity can be attributed to the breakthrough discovery of a gene associated with Alzheimer’s disease, which sparked renewed interest in degenerative diseases.
Figure 1 illustrates a line graph depicting the number of published articles in this period. The graph depicts that the number of articles on early onset dementia maintained an almost linear growth with slight, but ultimately insignificant, fluctuations from 1967 to 1990. However, starting in 1991, there was a marked acceleration in the publication rate, reflecting the growing attention and research efforts in this domain. Listed in Table 1 are the top 10 leading countries in this field.
The USA is the leading country in the production of publications and citations, followed by England and Germany (Figure 2). This indicates that these countries are crucial in advancing the research on early-onset symptoms of dementia.
Organizations and Authors
Out of 2316 organizations, the majority of the publications originate from University College London (UCL), totaling 110 publications and 8966 citations. The connections illustrated in Figure 3 highlight UCL’s extensive international reach. Similarly, other highly productive institutions like the University of California San Francisco and Mayo Clinic cluster with 79 and 155 organizations, respectively, indicating frequent cross-citations and collaborative research efforts. Notably, UCL and Mayo Clinic share a cluster due to their significant collaborative research and mutual citations.
The most prolific author in this field is Professor Bruce I. Miller, with 22 works focused on early-onset symptoms of dementia. Following closely is Nick C. Fox, a neurology professor at UCL, with 20 published works on the same topic. Both authors are highly cited, as demonstrated in the linkage chart in Figure 4. While many clusters in the chart reflect language and geographical proximity, Miller’s and Fox’s publications bridge these gaps, underscoring the significance of their contributions to the field.
Keyword Analysis
Out of 8055 total keywords analyzed, 23 keywords were identified with over 100 occurrences each. Leading the list is “Dementia,” appearing 1081 times, followed by “Alzheimer’s disease” (504), “Alzheimer’s-disease” (476), “diagnosis” (354), and “mild cognitive impairment” (334). These findings are visually represented in Figure 5, where all keywords stem from the central and highly cited term, “Dementia.” The figure’s color-coded clusters denote distinct research trajectories: some studies focus on early onset symptom identification and treatment strategies, while others delve into the fundamental science behind dementia’s pathology.
Despite this diversity in research focus, there’s significant crossover among keywords across studies, reflecting a shared interest in comprehensive approaches to understanding and addressing dementia. This collaborative trend is pivotal in advancing knowledge, bridging clinical insights with molecular understanding, and developing effective interventions. The prominence of particular keywords underscores their critical role in shaping research agendas and fostering interdisciplinary collaboration.
Moreover, the comprehensive analysis of keyword frequency and clustering in Figure 5 highlights emerging trends and focal points within dementia research. This cohesive technique not only enhances scientific discourse but also supports the expansion of targeted therapies aimed at mitigating the impact of dementia on global health.
Discussion
This bibliometric analysis of 2,433 papers across 82 countries provides a detailed perspective on the global landscape of research into early-onset dementia (EOD). The findings underline the United States’ leadership in research output and influence, consistent with broader trends in biomedical research where nations with robust infrastructure and substantial funding dominate scientific progress. The dramatic post-1990 surge in publications aligns with pivotal discoveries in Alzheimer’s disease genetics, such as the identification of mutations in the APP, PSEN1, and PSEN2 genes, which have reshaped research priorities and fostered advancements in understanding neurodegeneration.1
Socioeconomic Contexts and Global Disparities
The geographic distribution of research productivity highlights significant disparities rooted in socioeconomic factors. High-income countries, characterized by strong research funding and established academic ecosystems, account for the majority of publications and citations. For instance, countries like the United States and England, which rank among the top contributors, also lead in clinical trials and therapeutic innovations for dementia.2 However, the growing prevalence of dementia in low- and middle-income countries (LMICs), driven by aging populations and limited healthcare infrastructure, underscores a critical gap.3 Recent initiatives, such as the World Health Organization’s Global Dementia Observatory (GDO), represent essential steps toward bridging this divide by promoting international collaboration and capacity-building efforts.4
Institutional Leadership and Collaboration
University College London (UCL) exemplifies the impact of institutional leadership in advancing dementia research. As a nexus for interdisciplinary studies, UCL collaborates extensively with global institutions, including the University of California San Francisco and Mayo Clinic. This network amplifies research impact through shared expertise, particularly in neuroimaging and genetic studies. Similar collaborative models have proven effective in other fields, such as oncology, where consortia like the International Cancer Genome Consortium have accelerated discoveries by pooling resources.5 The importance of these partnerships in dementia research cannot be overstated, as they enable comprehensive approaches that integrate molecular biology, behavioral science, and clinical practice.
Individual Contributions and Emerging Paradigms
The contributions of key researchers such as Professors Bruce I. Miller and Nick C. Fox highlight the critical role of individual expertise in shaping the field. Miller’s work on frontotemporal dementia (FTD) and Fox’s advancements in neuroimaging have not only deepened our understanding of disease pathologies but also enhanced early detection strategies.6 Recent studies emphasize the value of early intervention, with evidence suggesting that addressing modifiable risk factors such as hypertension, diabetes, and physical inactivity can significantly delay the onset of dementia.7 These findings align with broader trends in precision medicine, where tailored approaches based on individual risk profiles are gaining traction.
Expanding Research Horizons
Keyword analysis reveals diverse research trajectories within the field, from molecular mechanisms to clinical management and non-pharmacological interventions. Leading terms such as “Dementia” and “Alzheimer’s disease” reflect sustained efforts to unravel the biological underpinnings of neurodegeneration. Emerging areas of interest include the role of gut microbiota in cognitive health and the application of artificial intelligence (AI) in early diagnosis and personalized treatment planning.8 For instance, machine learning algorithms have demonstrated promising accuracy in detecting dementia-related changes in imaging and speech patterns, heralding a new era of diagnostic innovation.9
Equally important is the increasing attention to lifestyle and psychosocial interventions. Studies on cognitive training, diet, and physical activity suggest these approaches can improve quality of life and delay disease progression.10 Digital health technologies, including mobile applications for cognitive assessment and virtual reality therapies, are also gaining momentum as accessible tools for both patients and caregivers.11 These advancements highlight the need for an integrative framework that combines pharmacological and non-pharmacological strategies to address the multifaceted nature of dementia.
Addressing Challenges and Future Directions
Despite significant progress, the heterogeneity of early-onset dementia presents persistent challenges in diagnosis and management. Unlike late-onset dementia, EOD often involves diverse pathologies, including frontotemporal lobar degeneration and vascular dementia, complicating standardized approaches to care.12 Moreover, the stigma surrounding dementia, particularly in LMICs, delays help-seeking behavior and access to treatment.13 Addressing these barriers requires not only scientific innovation but also targeted public health campaigns to raise awareness and reduce stigma.
Future research must prioritize inclusivity by involving underrepresented populations in clinical studies and fostering equitable access to emerging therapies. Collaborative initiatives like the Alzheimer’s Disease Neuroimaging Initiative (ADNI) and international funding mechanisms can facilitate these goals by creating platforms for data sharing and multidisciplinary collaboration.14 Additionally, integrating patient-centered approaches and leveraging advancements in big data analytics will be crucial for translating research into tangible benefits for diverse populations.
Strengths and Limitations
In contrast to traditional reviews, various bibliometric tools were utilized to visually map the dispersion of countries, journals, organizations, authors, and key terms in the studies on early onset signs of dementia. However, this study has certain limitations. Since all of the documents and articles were pulled from the Web of Science (WoS database), articles not included in WoS were excluded. Despite that, WoS remains the most commonly utilized database for bibliometric analysis and includes most articles related to early-onset dementia (EOD).
Conclusions
This study completed a bibliometric analysis of articles in the field of early-onset dementia (EOD) from 1967 to 2024. The USA, England, and Japan lead in research productivity, with the USA holding a significant position regarding publications and citations. University College London emerged as the most prolific institution, demonstrating extensive international collaborations. The most published author is Professor Bruce I. Miller, with significant contributions from Professor Nick C. Fox. The analysis highlights diverse research trajectories, including clinical management and molecular mechanisms of EOD, with “Dementia,” “Alzheimer’s disease,” and “mild cognitive impairment” as prominent keywords. This study provides a new perspective into research focal points and developments in EOD, suggesting future directions for collaborative and interdisciplinary research efforts to address this global health challenge.