Cardiovascular disease is incredibly complex and the disease process is not fully understood. However, it is increasingly being realised that the aetiology of the disease begins decades before any symptoms are noticed. In fact, evidence suggests that early childhood, and perhaps even the period of time in the womb, may have a strong influence on future risk of cardiovascular disease. Being overweight is a risk factor for cardiovascular disease, although this is an association and the cause and effect are complex. The cause is likely the increased levels of abdominal fat that lie around the internal organs, particularly the liver, which can also be preset in apparently normal weight individuals. This fat increases the risk of cardiovascular disease it is thought, because it results in systemic inflammation. In addition, the deposition of fat in the tissues around the internal organs may be a contributory factor in the formation of atherosclerosis.
However, the formation of atherosclerosis may take decades to become problematic, which raises the question of whether the disease process begins in early childhood. Childhood obesity levels are rising, and it is known that this can seriously increase future risk of cardiovascular disease. It was previously thought that the increase risk of cardiovascular disease from childhood obesity might be related to the childhood obesity persisting into adult life. However, evidence suggests that physiological changes occur in obese children that are likely irreversible and contribute to the risk of cardiovascular disease. For example, one group of researchers1 investigated the carotid intima-media thickness (a possible maker of atherosclerosis) of children in data taken from the Bogalusa Heart Study, and found an association with body mass index that persisted into adulthood. The results suggested a modest but significant effect of body mass index on intima-media thickness in children who were overweight.
Although intima-media thickness is not directly comparable to atherosclerosis, these results suggest that detrimental changes may begin in childhood. This is concerning because rates of childhood obesity are rising, and this might have long-term effects on future disease risk, even in the absence of other risk factors. There is generally a ‘J-shaped’ association between body mass index and mortality, as reported in a large prospective study of women2. Increased mortality occurred in those women who were reported underweight, but mortality fell as weight increased to normal. However, as the weight of the women increased above normal, mortality increased once again. Being overweight when young, therefore may increase the risk of cardiovascular disease, particularly if abdominal adipose tissue is excessive. However, some individuals can be overweight and have no additional risk of disease. These people likely have mostly subcutaneous stores of fat, which do not increase cardiovascular disease risk.
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