Complex presentations are often excluded from studies because they do not fit neatly into the simple nosological categorisations required for research power. This means that the most severe disorders are not studied adequately and patients most affected by early trauma are often not recognised by services. Both historically and currently, at the individual as well as the societal level, "dissociation from the acknowledgement of the severe impact of childhood abuse on the developing brain leads to inadequate provision of services. Assimilation into treatment models of the emerging affective neuroscience of adverse experience could help to redress the balance by shifting the focus from top-down regulation to bottom-up, body-based processing."