Background

Busselton Healthy Ageing study will  establish a powerful new resource for the ongoing investigation of the aetiology, treatment and prevention of most common human diseases related to ageing.

Epidemic rises in the incidence of many chronic diseases such as asthma, mental illness, and type 2 diabetes (T2D) have occurred in Australia and many other developed countries. Such diseases are associated with significant long-term morbidity and mortality, and are major public health problems both in Australia and worldwide. For instance, it has been estimated that by 2020 the metabolic syndrome will account for half of the global burden of disease and represent a major public health issue in most countries of the world. In 2003, 20% of the Australian population (~4 million people) had a chronic condition leading to disability. The causes and consequences of these common diseases and their relationship to ageing are not fully understood, making the formulation of effective preventive policies difficult.

The rising numbers and proportion of aged individuals in the Australian population reflects global demographic trends. The diseases associated with ageing are therefore becoming more prevalent, and the associated healthcare costs are having a significant economic impact in all countries. As the population ages, successive cohorts of older adults will account for increasingly larger segments of the Australian population. One of the major challenges facing developed nations is the increasing complexity of disease diagnosis, prevention, and treatment associated with ageing. Community-based studies offer the opportunity to formulate a more comprehensive analysis of disease aggregation within individuals, families and socioeconomic groups.

Physical and cognitive capabilities are terms used to describe an individual’s ability to undertake the physical and intellectual tasks of everyday living. Functional measures that assess these capabilities involve several body systems. For example, tests of standing balance require muscle strength, mental concentration and fine motor control, all of which decline with age. Physical capability peaks in the third decade of life and exhibits a gradual decline which then accelerates markedly beginning in the sixth decade. Decrements in muscle mass, strength and power are the primary factors in loss of independence with ageing. This is also true for most measures of cognitive capability, particularly memory, reasoning, processing speed and executive functions.

Despite the rising incidence and serious complications of many chronic adult diseases, their natural history and aetiology remain poorly defined. Simultaneously, we are in the midst of genomics and biomarker revolutions that are focused on specific aspects of medicine, epidemiology and drug discovery that may be applied to population health. It is clear that all of the common human diseases are the result of multiple, interacting genetic and environmental/behavioural factors. Recently, human genome epidemiology (HuGE) has had unprecedented success in discovering validated genes underlying common, complex diseases by undertaking genome-wide association scans (GWAS) of large, population-based samples. To understand the relationships of diseases within individuals and communities there is a need for human epidemiological, clinical and genetics research into common diseases associated with ageing using large, comprehensive, and longitudinal population-based resources.

In Western Australia, the necessary history, infrastructure and resources to support the creation of an outstanding population-based ageing cohort already exist. WA has a long history of population-based medical research. The core WA Data Linkage System (WADLS) data (www.datalinkage-wa.org.au/) have been recorded over 30 years, and are based on linkage within and between the WA statutory collections, Commonwealth datasets such as the PBS and MBS registers, aggregated ABS data (SEIFA), and additional registers and surveys. A number of internationally unique population-based disease registries are linked to the core datasets, e.g., mental health, birth defects, and cancer. The Family Connections project has recently linked families within the core WADLS, and is enabling novel genealogical and family-based health research.

The Busselton Health Study (BHS) has established a structure for population sampling, community participation and longitudinal, familial and cross-sectional studies of environmental and genetic factors associated with disease. The Shire of Busselton is a coastal community in the South-West of WA with a stable population of predominantly European descent. The BHS is one of the longest running epidemiological research programs in the world, with repeated cross-sectional surveys of adults listed on the electoral roll undertaken 1966 to 2007, with participation rates ranging from 64 to 91%. Cross-sectional studies of adults, focused on respiratory and cardiovascular phenotypes, have been conducted in 1966, ’69, ’72, ’75, ’78, ’81, ’90, and 2005/07. In 1994/95, a follow-up survey was conducted of all surviving participants previously surveyed. Approximately 3,500 adults attended each of the adult surveys in 1966, ‘69, ‘72, ‘85, ‘78 and ‘81; approximately 1,500 school children attended each of the surveys in ‘67, ‘70, ‘73 and ‘83 and 500 (high school only) attended in ‘77; 1,120 attended the survey of the elderly (65+) in ‘87; 5,700 attended the follow-up survey in ‘94/95; 4,268 adults and children attended the cross-sectional survey in 2005-07. There are a total of 16,000 individuals in the accumulated BHS database; the average number of surveys attended is 2.5 with 57% having attended ≥2 surveys and 25% having attended ≥4 surveys.

Underpinned by the WADLS, the BHS has produced a unique database containing 40 years of information related to respiratory and cardiovascular disease, human pedigree data, disease risk factors, lifestyle and environmental variables. To date, the BHS has produced over 250 peer-reviewed journal articles in journals including Nature, Nature Genetics, New England Journal of Medicine, and The Lancet. Research topics have primarily focused on respiratory medicine, cardiovascular disease and iron metabolism, with additional studies on endocrinology, gastrointestinal disease, cancer mortality, metabolic syndrome and diabetes. Genetic epidemiology has been a key activity of the BHS. The archived collection of data from these Busselton studies has been described as a National Treasure by the WA Government.