An approach seen across many areas of psychiatry is the biopsychosocial-cultural schema. This schema emphasises the child lives within a family, school, local environment context and there may need to be interventions at numerous parts of the individual and social ecology to achieve a successful outcome. Rather than consider biopsychosocial-cultural factors during the infant, child, early and late adolescent stages separately, this section will take an over-arching developmental view and integrate these various ecological influences at different stages of development. A developmental approach acknowledges differences in the child's integration of biological, emotional, cognitive and behavioural systems and differences peer and family interactions across the life span. Developmental theory highlights it is the interplay of these factors that determines whether development approximates to the normal trajectory or whether deviation occurs. The later, if significant, is synonymous with the presence of symptoms and impairment. The 'normal trajectory' does not imply there is a single pathway to a particular outcome. Critical aspects of the biopsychosocial frame are required, including for example an intact central nervous system, availability of at least one attachment figure and an environment with the potential of providing at least food and shelter. Other useful concepts in the developmental context are protective, resilience or vulnerability factors. We will refer to descriptors for the major development epochs: fetal, infant, child and adolescent periods, despite some conjecture about when difference stages begin and end. Developmental is, after all, continuous. Biological fetal determinants of later mental health include toxic fetal environmental factors and the adverse effects of maternal malnutrition. Toxic effects can be from infections (e.g. rubella, herpes, human immunodeficiency virus, cytomegalovirus and toxoplasmosis); excessive maternal alcohol intake and deficiency states such as folate deficiency, the later commonly following malnutrition. Genes controlling major organogenesis are operant during the fetal period and toxic effects at this stage can be catastrophic including mal-development of the central nervous system. Although birth-weight may give some indication of the success and traumas of the gestational period it is a very coarse and non-specific marker. However, intrauterine growth retardation (measures of which include both birth-weight and gestational age) is a useful predictor of later hyperactivity, academic performance and possibly other outcomes. Important psychosocial factors during the fetal period include maternal perception of social support, the development of attachment to the developing fetus and whether the wider system such as father, grandparents and wider community are involved or supportive. The infant phase is obviously influenced by persisting fetal factors. From a mental health perspective a psychological construct of major importance in this stage is attachment. Attachment theory has essentially either replaced or lead to profound modification of previously held psychodynamic and learning paradigms. Understanding of attachment has progressed with recent cognitive and developmental psychology research finding the infant’s competence is greater at an earlier age than previously thought. Early behaviours include the infant's ability to recognise their mother's voice in the hours after birth and preferential eye tracking around two months of age. One must remember attachment is not uni-directional but rather relates to the relationship between infant and primary caregiver. Attachment has both cross-sectional and longitudinal links with mental health. Up to 80% of the offspring of depressed mothers display insecure attachment. This attachment style is also related to the child’s delayed expressed language and cognitive development. As is expected the childhood period continues the development of the infant period including the attachment pattern established at that time. The child period is a time of continued cognitive, speech, language and psychological development underpinned by continued synapse formation, continuous (CNS) reorganisation and maturation of neuronal circuits. It is a time of an increased sense of self-efficacy, competence and mastery of more complex social circumstances. Social development includes a move from solitary play to parallel and then cooperative play, with the locus of contact not solely restricted to the family home. Relationships with non-family individuals such as school friends become more common, complex and incorporate increasing imagination and fantasy. Peers and group membership become important and the experience of rejection by peers can have major consequences including development of anxiety and lowered mood. Indeed children can develop both depressive and anxiety disorders of a degree of severity which justifies professional intervention. Consequences can include impaired social relationships, diminished social support, diminished self-esteem and increased deviant behaviour. These can then in turn result in further deterioration of the child’s mental state with a resulting downward spiral. Conversely, childhood can be a time of an increased sense of self-efficacy, competence and mastery of more complex social circumstances such as interactions in the school domain. Definitions of Adolescence vary are often culture bound. One could argue that adolescence, or at least its recognition as a significant developmental stage is a relatively recent phenomenon and one of most relevance to the affluent developed world. There are many societies where work, marriage and the taking on of adult type responsibilities, unfortunately including going to war, occur at ages where the typical western teenager is engrossed in adolescent experimentation and is very far from these things. From a biological perspective the onset of adolescence is defined by the hormonal changes of puberty and the effects these changes have on body morphology including the development of secondary sexual characteristics. Behaviour is in part gender-specific with greater levels of aggression in males and depression in females. Biological influences during the adolescent stage are not limited to physiological maturational processes. Environmental toxins include exposure to illicit drugs and legal substances such as cigarettes, alcohol and inappropriate use of over-the-counter medication. Psychological factors include increased capacity for self-reflective thinking and development of a more sophisticated sense of self. A more robust self-identity is related to the development of personal values with may include moral, political, sexual, religious or spiritual values as well as future educational and work aspirations. Much psychological development occurs within the context of the school environment. To conclude this discussion on aetiology, it should be acknowledged that several factors are not development stage specific but rather are factors that are influential across developmental phases. The family's resources; financial, emotional and cultural, and social economic class (SEC) are influential developmental factors. Socioeconomic disadvantage and poverty have been linked to not only child and adolescent behaviour problems and conduct disorder but also more bio-behavioural processes such as the exposure of children to spoken and written language and the number of encouragements and discouragements given to the child during the early years. Note it is simplistic to ascribe causation to family SEC, rather this is a summary of a complex variety of constructs, for example may include parent mental health, parent availability, dislocation from extended family resources and access to other resources that enrich the child’s development. Biological effects can be influential across the lifespan such as some genetic factors, for example the presence of a genetic mutation seen with Velocardiofacial syndrome or the persistence of problems caused by anoxic brain damage at birth. Parental influence is also a persisting developmental effect. For example parents who have a coercive parenting style will continue to demonstrate this parenting style unless helped to do otherwise. In turn coercive parenting is related to the development of oppositional defiant disorder and later conduct disorder. Finally, the child and family’s culture must be considered in any aetiological formulation. Culture affects many of the determinants of health, as well as the construction of whether a given phenomenon is a health issue. For examples some cultures are more willing to acknowledge youth suicide. Whilst clearly effecting data and statistical analysis, at a personal level help seeking behavior for suicidal youth is likely to be effected by social views on this issue. Culture is often seen as a strong developmental continuity. However, for some countries in the developing world cultural change is rapid and has profound effects on children, an example being prolonged parental absence due to adults following employment opportunities in major cities.