Early life experience and adult cardiovascular disease: longitudinal and case-control studies.

It has been postulated that experiences early in life influence cardiovascular risk in later adult life. This article considers 15 longitudinal and four case-control studies which, directly or indirectly, have examined the hypothesis concerning the prenatal and childhood origins of adult cardiovascular disease. Criteria laid down by Bradford Hill were used to assess whether these epidemiological studies provided sufficient evidence for a causal relation between experiences early in life and subsequent cardiovascular risk. No consistent dose-response relationship was found between the index of early life experience and adult cardiovascular disease. The relationships were usually non-specific with the index of early life experience being correlated with several causes of death, not only cardiovascular disease. The formulation of the hypothesis varied between the studies. Most reports dealt inadequately with the fact that the relation between adult cardiovascular risk and early life experience was confounded by persisting social and economic disadvantage. Overall these studies do not provide strong support for the hypothesis that experiences early in life determine the subsequent risk of cardiovascular disease. While future epidemiological studies may resolve this issue, the very nature of the hypothesis presents methodological problems that may prove to be insurmountable. Further progress in this field urgently requires the formulation of a clear and specific hypothesis.