In the early years, illnesses were studied only in terms of single causes; one agent led to one particular disease. However, we now know that the health of individuals and societies are affected by a combination of factors such as hereditary factors, living conditions, socioeconomic status and social support networks. A life course approach to health focuses on all ages and stages of life and takes into account a wide range of processes that interact and influence people’s health from birth to old age ( Kuh et al, 2003) and also has implications on the way health care needs of people are considered. Based on the understanding that one’s past and present life experiences are shaped by the wider socio-cultural context, we can study the current pattern of health and disease of an individual by looking into and examining their past life events for clues into present health related behaviour (WHO, 2000) such as smoking, excessive alcohol consumption, unhealthy diets and similar behaviours that have adverse effects on one’s health and overall well being.
Although, in the past, the Biomedical model of health which emphasizes on the biological determinants or external pathogens has proven to be effective in the control of massive infectious diseases ( Havelka et al, 2009), there is a crucial need to understand health and diseases from various other perspectives that take into account major influential factors such as biological, behavioural and psychosocial processes that run throughout the life of an individual and contribute towards both acquisition and attrition of physiological and psychological functioning. Such an approach aids in understanding the development and course taken by various diseases, leading to the formulation of preventive measures and treatment plans. A life course approach to health emphasizes on events from all stages of life, starting from the intrauterine environment and throughout adult life, subsequently studying how such events influence the risk for chronic illnesses and health outcomes later in life, which is why the narrow biomedical model has been broadened into an integrated model that looks at not only the biological determinants of health but also the psychosocial and behavioural aspects.
On a simpler note, life course approach aims to understand how biological, psychosocial and behavioural risk factors during the fetal period, infancy, childhood and early adulthood accumulate and increase the risk for a number of diseases. Timing of physical growth and psychological transitions are known to be influential in the manifestation of various adult chronic diseases and therefore strongly affects an individual’s capacity to be healthy (Osler, 2006). While one’s genetic makeup or external pathogens (biological factors) may determine the onset of an illness up to certain degree, it can be debated that this is intensified by various personal behaviours and societal influences. A classic example of a life course approach to health would be the field of gerontology which studies how people age by examining an array of biological, psychological, social and lifestyle factors. Furthermore, if we were to consider cigarette smoking, a detrimental health related behaviour and a frequently used example in health related research, we can say that although an individual’s family history of smoking( genetic influence) will definitely increase the risk of engaging in such behaviour, other factors such as exposure to smokers( peer/societal factor) or the need to live up to the expectations of others(psychosocial factor) will intensify the risk of smoking behaviour which, in turn, increases the risk for various health complications related to cigarette smoking, such as lung cancer, later in life.
The importance of a life course approach lies in its implications for the way an individual’s health is assessed, formulation of treatment plans based on past and ongoing events and training of health care professionals to equip them with a better understanding of peoples health and its underlying determinants ( WHO,2006). This paper focuses on the life course perspective on health, which is gradually becoming an efficient framework to study health and development of diseases, and also looks into the biological, psychosocial and behavioural processes that influence health throughout the lifespan.
TIME, CRITICAL PERIOD AND ACCUMULATION OF RISKS
The functional capacity of our physiological systems that increases during the early years of life reaches its peak in adulthood and begins to decline thereafter; external factors determine the intensity and speed of both the increase and decline. Therefore the lifespan perspective is defined by major concepts such as health trajectories, accumulation of risk factors, chains of risk, timing of exposure ( critical and sensitive periods), factors that mediate and modify the ‘exposure-disease’ association and various adaptive strategies (Wethington, 2005).
The life course perspective is a much broader approach than the ‘Barker hypothesis’ or the ‘Fetal origins hypothesis’ which focuses entirely on the relationships between early fetal environment and development of diseases later during adulthood and old age. It takes into account the contributions of both early ‘biological programming’ (Barker, 1992) and later adult lifestyle factors which lead to the formation of biological, psychological and social chains of risks (Power et al, 1999).
A number of researches (Smith, 2000; Lumey, 1998) and birth cohort studies reveal the existence of critical periods, not just during the intrauterine phase but also later in life, characterized by exogenous stimuli that have lasting effects on the structural and functional development of bodily systems leading to lifelong health implications. For example, fetal alcohol exposure during the first trimester is often associated with craniofacial abnormalities in conjunction with improper mental development (Fetal Alcohol Syndrome) as well as low birth weight (Coles, 1994). Similarly, there are various sensitive periods, mainly during childhood and adolescence, when the timing of exposure plays a crucial role in determining the development of lifelong adaptive strategies, social skills and health behaviours that have direct implications on development of illnesses later in life. For instance, the period between birth to 4 years is very crucial for ‘sensory refinement’ in children, whereby failure to attend to the differences in sensory stimuli can lead to a diminished ability to make sense of the broader social environment leading to deprivation of social interaction and formation of social relationships (characterized by accumulation of stress and anxiety) which will eventually lead to adverse effects on the health of individuals later in life.
Accumulation of risk factors over time also determines the likelihood of a disease occurring, for instance people who belonged to a poor socioeconomic environment as a child are more likely to have had poor educational attainment, exposure to poor eating habits and nutrition, air pollution, passive smoking, detrimental lifestyle choices, infections due to childhood neglect and inadequate social support, all of which carries onto a similar pattern in adulthood and increases the risk of adult health complications such as poor immune system, coronary heart diseases, high blood pressure and so on (Kuh & Ben-Schlomo, 2002). In addition, the life course approach aims to understand whether such early bio psychosocial factors lead to just additional risk or interact with later adulthood events to intensify long term health conditions.
Hence, the life course perspective combines the ‘Early programming model’ and ‘cumulative pathway model’; the former is concerned with Biopsychosocial events in early life, starting from the fetal period until childhood, that have life-long influences while the latter focuses on lifelong accumulation of stress through various social and behavioural expectations that ultimately affects an individual’s overall adaptive system. So, this approach focuses on the determinants of health from early developmental phase and also over the course of lifespan where ‘time’ takes the centre stage, focusing on different ‘exposure-timing’ interactions resulting in different health outcomes.
BIOPSYCHOSOCIAL DETERMINANTS OF HEALTH
Development of human beings is characterized by a number of biological, psychosocial and behavioural processes, each with different levels of importance at different developmental stages, and which involves growth, maintenance and loss of physiological and psychological functioning. Human development is, therefore, shaped by biological, social and behavioural factors working together (Myers et al). It is quite interesting to note that development is multidimensional in nature, involving the body, mind and emotions that interact and bring about significant changes at different stages in the lifespan and so it can be argued that the events that occur during such interactions or the individual lifestyle choices one makes will lead to either accumulation of risk or protective factors which will subsequently determine the susceptibility of individuals to adult diseases or chronic illnesses. So, the life course approach to health focuses on understanding the individual nature as well as the cumulative impact of such bio-psychosocial and behavioural factors that co-constructs development and also health in the long run.
A variety of behavioural factors or habits can have adverse effects on one’s health. Some of the most commonly known factors include smoking, alcohol consumption, dietary pattern, level of physical activity, sexual behaviour and substance abuse. While excessive consumption of alcohol is associated with liver cirrhosis, untimely death and hazards to health from alcohol related violence, smoking is one of the leading causes of coronary heart diseases, asthma, lung cancer and a reduced life expectancy by seven to eight years (NWPHO data, 2005). In addition, poor dietary pattern/habit established during early childhood can increase the risk for obesity or malnutrition, leading to further health complications later in life such as weak immune system and eventually a decrease in life expectancy.
Substance abuse and sexual behaviour (unprotected sex), like any other lifestyle habit, has devastating effects on health and general wellbeing, and in almost all cases they impact family and social relationships through events such as teenage pregnancy, domestic violence, unrest in the household, etc.
Socioeconomic condition of people shape their risk for diseases later in life since both harmful exposures and opportunities are patterned by one’s social environment, not to mention the life choices we make that are influenced by our social experiences. People interact with their social environment on a daily basis and such interactions affect their health either directly through psychobiological processes (experience of stress and anxiety) or indirectly leading to the development or modification of health related behaviours formerly discussed. The psychosocial factors that are known to impact one’s health status include the social support network, work environment (ideal vs. stressful), work-home balance, sense of security, autonomy and so on. Stress and anxiety brought upon by such processes can lead to various psychological conflicts such as loss of self-esteem, feelings of worthlessness, which will in turn affect the physiological functioning of the body. This brings us to the understanding that psychosocial processes or environment may have a role to play in disease aetiology (Cassel, 1974). In addition, it can also be argued that positive social support network facilitates behaviours that are considered healthy by the promotion of healthy eating, abstinence from substances and better adherence to treatments (Uchino, 2006).
In his paper, “Policy, Biology, and health”, Bortz emphasizes that biological factors occur in various combinations to determine the functional well being of individuals. Although the human genome is often regarded as the ultimate determinant of human health, there are other equally important factors that influence health and well being, such as threats presented by the external environment (agents) and deterioration of internal bodily functioning.
The life course approach to health is characterized by a temporal ordering of formerly mentioned biological, psychosocial and behavioural processes and is built on the view that these factors interact and have a cumulative influence on the development and course of illnesses in adulthood (Hertzman et al, 2001). So, the genetic makeup of individuals interact with intrauterine insults and various socially patterned exposures during childhood, adolescence, and early adulthood that determine the risk for a number of health conditions and also accounts for socioeconomic, gender and ethnic inequalities in health ( Kuh, Ben-Schlomo, Lynch, et al, 2003). This approach helps us address some of the most common and emerging health conditions at present such as obesity, asthma and diabetes.
In a study by Lamont et al in 2000, a number of early and later life factors were ordered temporally and the inter relationships were examined leading to the discovery of several potential disease pathway. In a similar study by Eriksson et al in 2001, these disease pathways were found to be influenced by a number of confounding factors and mediators and therefore, depending on the type and time of exposure, the pathways can be predominant in one of the following areas: biological, social, socio-biological and bio-social (Krieger, 2001). Specifically, if we consider respiratory problems like chronic bronchitis, improper lung development during the intrauterine period, in collaboration with later extraneous agents, will form the biological pathway to a greater risk of respiratory system dysfunction as an adult. Whereas if the individual’s socioeconomic condition has led to adverse exposures during childhood, followed by detrimental health behaviour such as smoking, then the pathway to respiratory diseases would be predominantly ‘social’. Likewise, the ‘socio-biological’ pathway is characterized by the exposure to harmful biological agents as a result of adverse socioeconomic conditions. Or it can be the other way around whereby frequent infections during childhood would come in the way of proper development, leading to a low socioeconomic position during adulthood.
RESEARCH AND CLINICAL IMPLICATIONS
We can say that the life course approach to health is based on the “Biopsychosocial model” that maintains that both macro level and micro level processes interact and produce multiple effects on health. But the question arises as to how biological factors (micro level) and psychosocial factors (macro level) interact if they are on different levels. In order to address this issue, researches in health psychology adopts the “system theory”, according to which “all levels in any entity are linked to each other hierarchically and that change in any one level will effect change in all other levels.” Based on this understanding, researchers often take an interdisciplinary and multivariate approach to study the interacting processes, both within an individual and at the macro level and maintains that the process of defining an illness should always be done in terms of the biological, psychological and social factors (Oken, 2000). Health psychologists also carry out various prospective studies to evaluate events or variables relating to a particular health condition, such as intervening the smoking habits of people in one society and not in another and looking into the differences in the rate or prevalence of respiratory conditions in both the groups. Prospective longitudinal study is perhaps one of the popular research designs that health psychology adopts in order to follow a group of people and assess them on a number of variables over a long period of time and provides a good measure of factors affecting health of an individual. While correlational research has often been criticized for its inability to determine the direction of causality, researchers often make use of the retrospective approach to rearrange and understand the past conditions and how they lead to the present situation.
The life course approach to health has various implications for clinical diagnosis of illnesses, development of treatment plans and training of health care professionals. By examining the Biopsychosocial processes underlying the lifespan development of individuals, health professional can formulate treatment plans and therapies unique to each individual; some may be a predominantly biological approach such as invasive methods while others may take a more psychological stance like cognitive behavioural therapy or relaxation therapy. Therefore, we can understand the health status of people only by viewing them in the social and psychological contexts ( Belar, 1997).
Health psychology strives to understand health in all its dimensions, recognizing all internal and external exposures throughout the life of an individual, giving more importance to the events that occur during the fetal period, childhood and early adulthood and their subsequent impact on adult health and development of illnesses. By downplaying the earlier assumptions that only current exposures or factors influence the onset of a disease or that illness is caused entirely by biological agents, it takes a rather multidimensional and multidirectional approach, taking into consideration the biological, psychosocial and behavioural processes occurring throughout the lifespan, their interactions and the cumulative impact on one’s health and disease occurrence. In short, it integrates the lifelong progression of individuals from the intrauterine environment to the larger social environment; a progression that encompasses a series of social and biological factors that work together to determine the health status of individuals in the long run.
Health psychology, therefore, tries to explore all the underlying causes of ill health and subsequently develop treatment procedures to overcome them.
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