"Initial symptoms of early-onset dementia in Japan: A nationwide survey"

Ayako Edahiro, Deputy Director of Specialist Department, Dementia and Mental Health, Independence Promotion and Mental Health Research Team

◆Introduction

Research efforts regarding how to create a dementia-friendly society are increasing in various fields and local communities. Dementia that develops in individuals at a relatively young age is known as early-onset (or young-onset) dementia. Among the 'Ambassadors of Hope,' the term describing a group of individuals appointed in local communities to deliver messages from individuals with dementia themselves, there are many active individuals with early-onset dementia. These particular 'Ambassadors of Hope' are individuals living with dementia who are appointed by the government to take a leading role in communicating their voices to the public.

Early-onset dementia affects people in the prime of their lives, often resulting in financial problems, anxiety, conflict, and social isolation due to the greater complexity of challenges compared with late-onset dementia, such as overlaps in patient caregiving, child-rearing, and continued employment. The initial symptoms of early-onset dementia are often noticed by others in individual workplaces or community settings. Raising awareness and establishing support systems within companies are crucial to enable supervisors and coworkers to connect individuals exhibiting symptoms to appropriate services. Informing society about the symptoms of early-onset dementia may promote early recognition by others and facilitate the provision of appropriate support within the community.

Early-onset dementia is diagnosed less frequently than late-onset dementia and public awareness within local communities especially remains inadequate. Understanding early-onset dementia is vital for all members of society to foster a community in which individuals feel safe, regardless of when, where, or by whom the disease is experienced. This study aimed to promote greater societal awareness of early-onset dementia.

◆Methods for Evaluating the Condition of Individuals with Rare Variants of Early-Onset Dementia

Early-onset dementia is diagnosed in a small number of individuals, and does not always manifest with typical symptoms associated with the more widely recognized late-onset dementia. Early-onset dementia is occasionally misdiagnosed as depression or other mental health conditions, resulting in delayed diagnosis. Although prior research has examined the clinical symptoms of early-onset dementia, no study has yet specifically focused on the initial symptoms before diagnosis. Consequently, we sought the cooperation of medical and caregiving institutions, along with consultation offices across 12 regions of Japan, to support our research on individuals with early-onset dementia, which is still a rare disease. Subsequently, we investigated the living conditions of individuals diagnosed with early-onset dementia and their families through these institutions.

This study included individuals diagnosed with early-onset dementia aged between 18 and 64 years. The study was conducted in two phases. In the first phase, we sought cooperation from medical and caregiving institutions that provide healthcare, nursing care, and consultation services to individuals with early-onset dementia. In the second phase, we requested that these institutions distribute a questionnaire to each individual and their families.

The questionnaire included information such as age, sex, age at dementia onset, initial symptoms before diagnosis, and diagnosis of dementia subtype. The evaluation items were designed in a format that allowed individuals and their families to easily give information regarding six listed symptoms: 1) loss of memory, 2) difficulty in word generation, 3) irritability, 4) loss of motivation, 5) increased mistakes in the workplace or domestically, and 6) unusual behaviors or attitudes other than those listed.

◆Reflection on initial symptoms according to differential diagnosis of early-onset dementia

In the present study, we analyzed survey data from 770 individuals with early-onset dementia diagnosed with one of the following common types: Alzheimer's disease, vascular dementia, frontotemporal dementia, and dementia with Lewy bodies. The most common form of dementia was early-onset Alzheimer's disease (EO-AD), with 576 individuals), followed by early-onset vascular dementia (EO-VaD), early-onset frontotemporal dementia (EO-FTD), and early-onset dementia with Lewy bodies (EO-DLB).

At onset, 57.4% of the individuals were employed and, in many cases, their spouses noticed the initial symptoms (64.4%). The most common initial symptom was 'loss of memory' (69.6%), followed by 'increased mistakes in the workplace or domestically' (43.8%).

　Regarding the frequency of initial symptoms at diagnosis, the symptom 'loss of memory' was the most common in EO-AD (75.7%), whereas the symptom 'difficulty in word generation' was the most common in EO-VaD (41.3%) and EO-FTD (31.3%). The 'loss of motivation' symptom was most common in EO-FTD (34.9%); however, no statistically significant difference was observed between EO-VaD (26.3%) and EO-DLB (29.0%). The symptom 'increased mistakes in the workplace or domestically' was more common in the EO-FTD (49.4%) and EO-AD (46.5%) groups, whereas the frequency of 'unusual behaviors or attitudes other than those listed' showed a statistically significant difference (34.9%) (Figure 1).

Figure 1 Frequency of diagnosis for the initial symptoms

Analysis of the relationships among factors, including initial symptoms, sex, age, and residence status, revealed that the symptom 'loss of memory' was more common among women, while 'difficulty in word generation' was more common among individuals living alone. The symptom 'irritability' was more common among men, while 'increased mistakes in the workplace or domestically' was observed more often in younger individuals (under 58 years of age) and those employed at onset.

In addition to analysis by diagnosis, we examined multiple factors, including sex and age, yielding the following results:

The symptom of 'loss of memory' was more common among women, most of whom were eventually diagnosed with EO-AD.

-The symptom 'difficulty in word generation' was more common among individuals living alone, and most of these individuals were eventually diagnosed with EO-VaD or EO-FTD.

-The symptom of 'irritability ' was more common among men, most of whom were eventually diagnosed with EO-VaD.

-The 'loss of motivation' symptom was largely associated with the eventual diagnosis of EO-FTD.

The symptom 'increased mistakes in the workplace or domestically' was more common among individuals who were employed at the time of onset, with most eventually being diagnosed with EO-AD or EO-FTD.

Symptoms of 'unusual behaviors or attitudes other than those listed' were more common among those eventually diagnosed with EO-FTD.

(Table 1, based on Appendix Tables)

Table 1 Diagnosis and factors showing statistical differences in multivariate analysis

◆What is the relationship between diagnosis and initial symptoms?

The results of this study showed that the frequency and manifestations of symptoms may vary depending on the type of early-onset dementia eventually diagnosed. In particular, the symptom 'loss of memory' was a characteristic of EO-AD, whereas 'difficulty in word generation' was the most common symptom in EO-VaD and EO-FTD. In EO-FTD, symptoms such as 'loss of motivation', 'increased mistakes in the workplace or domestically', and 'unusual behaviors or attitudes other than those listed' are all characteristic. These findings have significant implications for the early diagnosis and appropriate treatment of early-onset dementia.

By communicating this information to the public, we may raise awareness, encouraging people to think, 'My colleague, family member, or even I have this symptom; it might be a disease. Medical consultations may be necessary. Early recognition of symptoms and prompt diagnosis can facilitate appropriate treatment and timely adjustments at work and home, helping individuals maintain a better quality of life. Furthermore, early diagnosis could facilitate individuals to access psychological support and find opportunities to connect with others who have faced similar experiences.

Adjustments that create an equitable and accessible system for individuals with difficulties or specific needs are referred to as reasonable accommodations. The results of this study will contribute to building a society in which the early symptoms of early-onset dementia are widely recognized, thus enabling early diagnosis and implementation of reasonable accommodations in workplaces, homes, and local communities. Furthermore, these findings will support advocacy efforts to encourage government initiatives that promote awareness of early-onset dementia among companies, emphasizing the importance of symptom recognition and the establishment of reasonable accommodations, with the understanding that anyone in the workforce may develop early-onset dementia. Additionally, our findings will serve as a valuable resource for occupational physicians to support the diagnosis of dementia by considering initial symptoms.

As this study was based on a multiple-choice questionnaire, it was difficult to confirm the presence of additional symptoms. Nevertheless, this study successfully revealed the relationships among initial symptoms, diagnoses, and social factors through a nationwide investigation of this rare disease.

In the future, it will be essential to enhance the public understanding of early-onset dementia to provide a detailed and individualized diagnosis and support based on epidemiological research.

　

This study was conducted as part of the nationwide AMED research project, the 'Japan National Early-Onset Dementia Prevalence Study' (JNEP Study), with the aim of investigating and categorizing the initial symptoms of early-onset dementia prior to diagnosis according to the dementia type.

(https://www.tmghig.jp/research/AMED-research/index.html)　

A Edahiro, T Okamura, T Arai, et al. Initial symptoms of early-onset dementia in Japan: nationwide survey. Psychogeriatrics. 2023 May;23(3):422-433. doi: 10.1111/psyg.12949. Epub 2023 Feb 22. PMID: 36814116