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We discuss evolutionary perspectives on two neurodevelopmental disorders: attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). Both have a genetic background, and we explore why these genes may have survived the process of natural selection. We draw on the concept of evolutionary mismatch, in which a trait that may have conferred advantages in the past can become disadvantageous when the environment changes. We also describe the non-genetic influences on these conditions. We point out that children with neurodevelopmental conditions are more likely to suffer maltreatment, so it is important to consider both the genes and the environment in which children have grown up. In hunter-gatherer societies, ADHD may have favoured risk-taking, which may explain why it has survived. The contemporary model of schooling, in which children are expected to sit still for many hours a day, does not favour this. Understanding ADHD in terms of an evolutionary mismatch therefore raises ethical issues regarding both medication and the school environment. ASDs are far more heterogeneous and are characterised by high heritability and low reproductive success. At the severe end of the spectrum, ASD is highly disadvantageous and often co-occurs with intellectual disability. On the other hand, high-functioning ASD may have been adaptive in our evolutionary past in terms of the potential for the development of specialist skills and can still be so today in the right environment.
Throughout human evolutionary history, infants and children have been dependent on adult caregivers for survival. The care that adults give is greatly influenced by prevailing conditions, including the availability of food and their social contacts, and also by their own experience of care. We use an evolutionary perspective to discuss possible reasons why children may suffer trauma at the hands of their parents and consider how children have adapted in response to such trauma to maximise their chances of survival in order to reach reproductive age and produce their own offspring. We examine how child maltreatment might differ at the hands of mothers, fathers and step-parents and discuss parent–offspring conflict, life history theory, attachment theory and differential susceptibility to help explain the complexity of childhood trauma. We end with recommendations for clinical practice.
Bidirectional longitudinal relationships between depression and diabetes have been observed, but the dominant direction of their temporal relationships remains controversial.
Methods
The random-intercept cross-lagged panel model decomposes observed variables into a latent intercept representing the traits, and occasion-specific latent ‘state’ variables. This permits correlations to be assessed between the traits, while longitudinal ‘cross-lagged’ associations and cross-sectional correlations can be assessed between occasion-specific latent variables. We examined dynamic relationships between depressive symptoms and insulin resistance across five visits over 20 years of adulthood in the population-based Coronary Artery Risk Development in Young Adults (CARDIA) study. Possible differences based on population group (Black v. White participants), sex and years of education were tested. Depressive symptoms and insulin resistance were quantified using the Center for Epidemiologic Studies Depression (CES-D) scale and the homeostatic model assessment for insulin resistance (HOMA-IR), respectively.
Results
Among 4044 participants (baseline mean age 34.9 ± 3.7 years, 53% women, 51% Black participants), HOMA-IR and CES-D traits were weakly correlated (r = 0.081, p = 0.002). Some occasion-specific correlations, but no cross-lagged associations were observed overall. Longitudinal dynamics of these relationships differed by population groups such that HOMA-IR at age 50 was associated with CES-D score at age 55 (β = 0.076, p = 0.038) in White participants only. Longitudinal dynamics were consistent between sexes and based on education.
Conclusions
The relationship between depressive symptoms and insulin resistance was best characterized by weak correlations between occasion-specific states and enduring traits, with weak evidence that insulin resistance might be temporally associated with subsequent depressive symptoms among White participants later in adulthood.
Issues of sexual reproduction lie at the core of evolutionary thinking, which often places an emphasis on how individuals attempt to maximise the number of successful offspring that they can produce. At first sight, it may therefore appear that individuals who opt for gender-affirming medical interventions are acting in ways that are evolutionarily disadvantageous. However, there are persuasive hypotheses that might make sense of such choices in evolutionary terms and we explore these here. It is premature to claim knowledge of the extent to which evolutionary arguments can usefully be applied to issues of gender identity, although worth reflecting on the extent to which nature tends towards diversity in matters of sex and gender. The importance of acknowledging and respecting different views in this domain, as well as recognising both the uncertainty and likely multiplicity of causal pathways, has implications for clinicians. We make some suggestions about how clinicians might best respond when faced with requests from patients in this area.
LEARNING OBJECTIVES
After reading this article you will be able to:
• understand evolutionary arguments about diversity in human gender identity
• identify strengths and weaknesses in evolutionary arguments applied to transgender issues
• appreciate the range and diversity of gender experience and gender expression among people who present to specialist gender services, as well as the likely complexities of their reasons for requesting medical intervention.
We argue that current debates about attention-deficit hyperactivity disorder (ADHD) can be considered afresh using an evolutionary lens. We show how the symptoms of ADHD can often be considered adaptive to their specific environment. We suggest that, from an evolutionary point of view, ADHD symptoms might be understood to result from an ‘evolutionary mismatch’, in which current environmental demands do not fit with what evolution has prepared us to cope with. For example, in our ancestral environment of evolutionary adaptedness (EEA), children were not expected to sit still and concentrate on academic tasks for many hours a day. Understanding ADHD in terms of such a ‘mismatch’ raises significant issues regarding the management of childhood ADHD, including ethical ones. An approach based on the concept of mismatch could provide an alternative to current debates on whether ADHD results from nature or nurture and whether it is under- or over-diagnosed. It would allow clinicians and policy makers to take both the child and the environment into account and consider what might be desirable and feasible, both in society and for specific children, to lessen the mismatch.
LEARNING OBJECTIVES
• Grasp the concept of ADHD as an ‘evolutionary mismatch’
• Understand the issues raised by this perspective, including ethical ones
• Appreciate how a transparent discussion of these issues might inform decisions about management, medication and schooling
Nursing home residents are at risk for acquiring and transmitting MDROs. A serial point-prevalence study of 605 residents in 3 facilities using random sampling found MDRO colonization in 45% of residents: methicillin-resistant Staphylococcus aureus (MRSA, 26%); extended-spectrum β-lactamase–producing Enterobacteriaceae (ESBL, 17%); vancomycin-resistant Enterococcus spp. (VRE, 16%); carbapenem-resistant Enterobacteriaceae (CRE, 1%). MDRO colonization was associated with history of MDRO, care needs, incontinence, and catheters.
The traditional disease model, still dominant in psychiatry, is less than ideal for making sense of psychological issues such as the effects of early childhood experiences on development. We argue that a model based on evolutionary thinking can deepen understanding and aid clinical practice by showing how behaviours, bodily responses and psychological beliefs tend to develop for ‘adaptive’ reasons, even when these ways of being might on first appearance seem pathological. Such understanding has implications for treatment. It also challenges the genetic determinist model, by showing that developmental pathways have evolved to be responsive to the physical and social environment in which the individual matures. Thought can now be given to how biological or psychological treatments – and changing a child's environment – can foster well-being. Evolutionary thinking has major implications for how we think about psychopathology and for targeting the optimum sites, levels and timings for interventions.
Before 1977 there was little work done with eating disorders in the psychiatric unit at Burnley General Hospital. The hospital dietetic department was aimed mainly at special diets for medical, surgical, and paediatric patients and services for the obese. Many patients with anorexia nervosa were treated on paediatric or medical wards, until in the early ‘80s, following the establishment of a clinical psychology department, a principal-grade psychologist was appointed.