Prevalence and geographical variation of dementia in New Zealand from 2012 to 2015: Brief report utilising routinely collected data within the Integrated Data Infrastructure

Associations of hospital-treated infections with subsequent dementia: nationwide 30-year analysis

Infections, which can prompt neuroinflammation, may be a risk factor for dementia1-5. More information is needed concerning associations across different infections and different dementias, and from longitudinal studies with long follow-ups. This New Zealand-based population register study tested whether infections antedate dementia across three decades. We identified individuals born between 1929 and 1968 and followed them from 1989 to 2019 (n = 1,742,406, baseline age = 21-60 years). Infection diagnoses were ascertained from public hospital records. Dementia diagnoses were ascertained from public hospital, mortality and pharmaceutical records. Relative to individuals without an infection, those with an infection were at increased risk of dementia (hazard ratio 2.93, 95% confidence interval 2.68-3.20). Associations were evident for dementia diagnoses made up to 25-30 years after infection diagnoses. Associations held after accounting for preexisting physical diseases, mental disorders and socioeconomic deprivation. Associations were evident for viral, bacterial, parasitic and other infections, and for Alzheimer's disease and other dementias, including vascular dementia. Preventing infections might reduce the burden of neurodegenerative conditions.

Dementia, dementia's risk factors and premorbid brain structure are concentrated in disadvantaged areas: National register and birth-cohort geographic analyses

INTRODUCTION

Dementia risk may be elevated in socioeconomically disadvantaged neighborhoods. Reasons for this remain unclear, and this elevation has yet to be shown at a national population level.

METHODS

We tested whether dementia was more prevalent in disadvantaged neighborhoods across the New Zealand population (N = 1.41 million analytic sample) over a 20-year observation. We then tested whether premorbid dementia risk factors and MRI-measured brain-structure antecedents were more prevalent among midlife residents of disadvantaged neighborhoods in a population-representative NZ-birth-cohort (N = 938 analytic sample).

RESULTS

People residing in disadvantaged neighborhoods were at greater risk of dementia (HR per-quintile-disadvantage-increase = 1.09, 95% confidence interval [CI]:1.08-1.10) and, decades before clinical endpoints typically emerge, evidenced elevated dementia-risk scores (CAIDE, LIBRA, Lancet, ANU-ADRI, DunedinARB; β's 0.31-0.39) and displayed dementia-associated brain structural deficits and cognitive difficulties/decline.

DISCUSSION

Disadvantaged neighborhoods have more residents with dementia, and decades before dementia is diagnosed, residents have more dementia-risk factors and brain-structure antecedents. Whether or not neighborhoods causally influence risk, they may offer scalable opportunities for primary dementia prevention.

Prevalence of dementia among older age people and variation across different sociodemographic characteristics: a cross-sectional study in Bangladesh

Background

Dementia is a significant global health issue, particularly for low-income and middle-income countries which majorly contribute to the dementia cases reported globally (67%). We estimated the prevalence of dementia among older people in Bangladesh and compared the estimate across different sociodemographic characteristics and divisions.

Methods

A cross-sectional study was conducted in 2019 among individuals aged 60 years or older in seven administrative divisions in Bangladesh. Equal numbers of male and female participants were recruited from each division through a multi-stage random sampling technique. Recruitment was proportionally distributed in urban and rural areas in each division. Following consent, the Mini Mental State Examination (MMSE) was performed on all participants. Dementia was defined as an MMSE score of <24 out of 30. Data on age, sex, education, marital status, occupation, socioeconomic status, and type of community (urban or rural) were obtained using a structured questionnaire to compare the prevalence of dementia across different sociodemographic characteristics.

Findings

Between January and December 2019, 2795 individuals were recruited including ∼400 from each of the seven administrative divisions. The mean age was 67 years (SD: 7), 68% were from rural areas and 51% were female. The prevalence of dementia was 8.0% (95% CI: 7.0-8.9%) with variations across age, sex, education, marital status, occupation, and division. No variations in prevalence were observed across urban/rural locations or socioeconomic status. After adjusting for age, sex, education, occupation and marital status, the odds of dementia was two times higher in females than males (OR: 2.15, 95% CI: 1.43-3.28); nine times higher in people aged ≥90 years than people aged 60-69 years (OR: 9.62, 95% CI: 4.79-19.13), and three times higher in people with no education compared to those who had completed primary school (OR: 3.10, 95% CI: 1.95-5.17).

Interpretations

The prevalence of dementia is high in Bangladesh and varies across sociodemographic characteristics with a higher prevalence among females, older people, and people with no education. There is an urgent need to identify the key risk factors for dementia in developing countries, such as Bangladesh, to inform the development of context-relevant risk reduction and prevention strategies.

Funding

None.

Dementia and cataract surgery in Australia and New Zealand

BACKGROUND

Cataract surgery improves quality of life and reduces cognitive deterioration.

OBJECTIVES

This paper discusses the health implications of low vision, commonly related to cataracts, in older adults. A recent publication reported that cataract surgery reduces the risk of dementia by 30% over 10 years.

METHODS

We searched Medline from inception to January 2023. We also conducted backward and forward citation searches of included studies and set up alerts to identify studies published after the search date. We performed discussion groups with multidisciplinary experts.

RESULTS

This article provides a broad description of the importance of vision for cognitive function. We discuss access to public-funded cataract surgery in Australia and New Zealand and how this impacts population benefits.

CONCLUSIONS

We have evidence that cataract surgery can decrease the risk of dementia. This is an important topic that deserves recognition as part of an overall ageing response by policymakers and health professionals.

Dementia prevalence estimation among the main ethnic groups in New Zealand: a population-based descriptive study of routinely collected health data

OBJECTIVE

Estimates of dementia prevalence in New Zealand (NZ) have previously been extrapolated from limited Australasian studies, which may be neither accurate nor reflect NZ's unique population and diverse ethnic groups. This study used routinely collected health data to estimate the 1-year period prevalence for diagnosed dementia for each of the 4 years between July 2016 and June 2020 in the age 60+ and age 80+ populations and for the four main ethnic groups.

DESIGN

A population-based descriptive study.

SETTING

Seven national health data sets within the NZ Integrated Data Infrastructure (IDI) were linked. Diagnosed dementia prevalence for each year was calculated using the IDI age 60+ and age 80+ populations as the denominator and also age-sex standardised to allow comparison across ethnic groups.

PARTICIPANTS

Diagnosed dementia individuals in the health datasets were identified by diagnostic or medication codes used in each of the data sets with deduplication of those who appeared in more than one data set.

RESULTS

The crude diagnosed dementia prevalence was 3.8%-4.0% in the age 60+ population and 13.7%-14.4% in the age 80+ population across the four study years. Dementia prevalence age-sex standardised to the IDI population in the last study period of 2019-2020 was 5.4% for Māori, 6.3% for Pacific Islander, 3.7% for European and 3.4% for Asian in the age 60+ population, and 17.5% for Māori, 22.2% for Pacific Islander, 13.6% for European and 13.5% for Asian in the age 80+ population.

CONCLUSIONS

This study provides the best estimate to date for dementia prevalence in NZ but is limited to those people who were identified as having dementia based on data from the seven included data sets. The findings suggest that diagnosed dementia prevalence is higher in Māori and Pacific Islanders. A nationwide NZ community-based dementia prevalence study is much needed to confirm the findings of this study.

Anti-dementia medication use in Aotearoa New Zealand: An exploratory study using health data from the Integrated Data Infrastructure (IDI)

OBJECTIVE

Anti-dementia medications such as acetylcholinesterase inhibitors are an important part of the management pathway for dementia. However, there are limited data in New Zealand that have examined the rates and patterns of use of funded anti-dementia medication and how use differs with ethnicity, age and sex.

METHODS

This was a retrospective population-based descriptive study. Using the Integrated Data Infrastructure, we identified individuals of all ages coded for a diagnosis of dementia and estimated the proportion dispensed funded anti-dementia medication - donepezil tablets and rivastigmine patches - between 1 July 2016 and 30 June 2020. Rates of medication use in five main ethnic groups (Māori, Pacific peoples, Asian, European, and Middle Eastern, Latin American and African) in the <65, 65-79 and 80 and over (80+) age groups were compared and also between males and females in all sub-groups. Log-binomial models were used to calculate relative risks to determine any differences in anti-dementia medication use in the five ethnic groups and the three age groups and between males and females in each of the four study years.

RESULTS

Overall, one-third of the dementia population received a funded anti-dementia medication in the total population (all ages) between 2016 and 2020. Donepezil tablets were dispensed in 31.6-34.0% and rivastigmine patches in 1.4-2.1% across the four study years. Compared to people of European ethnicity, Māori, Pacific peoples, and Middle Eastern, Latin American and African groups were less likely to be dispensed an anti-dementia medication (Māori: relative risk = 0.79-0.81, p < 0.0001; Pacific peoples: relative risk = 0.72-0.74, p < 0.0001; Middle Eastern, Latin American and African: relative risk = 0.73-0.78, p < 0.05). Compared to the age 80+ group, the 65-79 age group was more likely (relative risk = 1.50-1.54, p < 0.0001), while the age <65 group was less likely (relative risk = 0.67-0.71, p < 0.0001) to be dispensed an anti-dementia medication. There were no statistically significant differences in anti-dementia medication use between males and females.

CONCLUSION

This study provides important information about funded anti-dementia medication use in New Zealand and how this differs by ethnicity, age and sex. Despite higher dementia prevalence in Māori and Pacific peoples, these groups were less likely to receive funded anti-dementia medication.

Prevalence of young-onset dementia: nationwide analysis of routinely collected data

INTRODUCTION

Young-onset dementia prevalence is understudied internationally. Previous studies have been limited by low case numbers, reliance on single sources of routinely collected health data for case identification and inclusion of a limited age range. Our objective was to determine the 1-year period prevalence of diagnosed dementia in people aged 0-64 in the entire New Zealand population using routinely collected health data.

METHODS

A population-based descriptive study was carried out in New Zealand (population 4.8 million) using routinely collected deidentified health data from 2016 to 2020. Dementia cases in seven linked health datasets in the New Zealand Integrated Data Infrastructure were identified using diagnostic codes and/or use of antidementia medication. Prevalence for each of the four study years was calculated by age, sex and ethnicity.

RESULTS

From a total population of 4 027 332-4 169 754 individuals aged 0-64, we identified 3396-3474 cases of 'all-cause' dementia in each of the study years (prevalence crude range: 83-84/100 000 people aged 0-64; 139-141/100 000 people aged 30-64 years; 204-207/100 000 people aged 45-64 years). Age-standardised prevalence was higher in males than females. Age-standardised and sex-standardised prevalence was higher in Māori and Pacific People than European and Asian.

DISCUSSION

By using a large study population and multiple national health datasets, we have minimised selection bias and estimated the national prevalence of diagnosed young-onset dementia with precision. Young-onset dementia prevalence for the total New Zealand population was similar to reported global prevalence, validating previous estimates. Prevalence differed by ethnicity, which has important implications for service planning.

Longitudinal Associations of Mental Disorders With Dementia: 30-Year Analysis of 1.7 Million New Zealand Citizens

IMPORTANCE

Mental disorders are an underappreciated category of modifiable risk factors for dementia. Developing an evidence base about the link between mental disorders and dementia risk requires studies that use large, representative samples, consider the full range of psychiatric conditions, ascertain mental disorders from early life, use long follow-ups, and distinguish between Alzheimer disease and related dementias.

OBJECTIVE

To test whether mental disorders antedate dementia across 3 decades of observation.

DESIGN, SETTING, AND PARTICIPANTS

This population-based administrative register study of mental disorders and Alzheimer disease and related dementias included all individuals born in New Zealand between 1928 and 1967 who resided in the country for any time during the 30-year observation period between July 1988 and June 2018. Data were from the New Zealand Integrated Data Infrastructure, a collection of whole-of-population administrative data sources linked at the individual level. Data were analyzed from October 2020 to November 2021.

EXPOSURES

Diagnoses of mental disorders were ascertained from public-hospital records.

MAIN OUTCOMES AND MEASURES

Diagnoses of dementia were ascertained from public-hospital records, mortality records, and pharmaceutical records.

RESULTS

Of 1 711 386 included individuals, 866 301 (50.6%) were male, and individuals were aged 21 to 60 years at baseline. Relative to individuals without a mental disorder, those with a mental disorder were at increased risk of developing subsequent dementia (relative risk [RR], 4.24; 95% CI, 4.07-4.42; hazard ratio, 6.49; 95% CI, 6.25-6.73). Among individuals with dementia, those with a mental disorder developed dementia a mean of 5.60 years (95% CI, 5.31-5.90) earlier than those without a mental disorder. Associations held across sex and age and after accounting for preexisting chronic physical diseases and socioeconomic deprivation. Associations were present across different types of mental disorders and self-harm behavior (RRs ranged from 2.93 [95% CI, 2.66-3.21] for neurotic disorders to 6.20 [95% CI, 5.67-6.78] for psychotic disorders), and were evident for Alzheimer disease (RR, 2.76; 95% CI, 2.45-3.11) and all other dementias (RR, 5.85; 95% CI, 5.58-6.13).

CONCLUSIONS AND RELEVANCE

In this study, mental disorders were associated with the onset of dementia in the population. Ameliorating mental disorders in early life might also ameliorate neurodegenerative conditions and extend quality of life in old age.