[Life leaves its marks].
BACKGROUND: The article highlights how environmental factors early in life, in combination with genetic vulnerability, can influence development and partly explain variations in mental health. MATERIAL AND METHOD: A selection of key articles identified on Medline. RESULT: The plasticity of a child's brain makes it particularly susceptible to environmental factors. This provides a significant potential for learning and adaptation, but also causes vulnerability with respect to, for instance, mental illness. There are no studies showing that a specific trauma or strain causes a specific psychological disorder later in life. Nonetheless, recent studies show that certain environmental factors in early life could have a lasting impact on a child's psychosocial behaviour. The article sums up some of these findings. CONCLUSION: Early preventive measures are particularly important in cases where a biological vulnerability occurs. It is equally important to have realistic expectations with respect to the results of the various measures. Not everything can be returned to normalcy, though it is always possible to promote a development potential.