The Strategies of the Genes: Genomic Conflicts, Attachment Theory, and Development of the Social Brain

Abstract

I describe and evaluate the hypothesis that effects from parent-offspring conflict and genomic imprinting on human neurodevelopment and behavior are central to evolved systems of mother-child attachment. The psychological constructs of Bowlby's attachment theory provide phenomenological descriptions of how attachment orchestrates affective-cognitive development, and patterns of imprinted gene expression and co-expression provide evidence of epigenetic and evolutionary underpinnings to human growth and neurodevelopment. Social-environmental perturbations to the development of normally-secure attachment, and alterations to evolved systems of parent-offspring conflict and imprinted-gene effects, are expected to lead to specific forms of maladaptation, manifest in psychiatric conditions affecting social-brain development. In particular, under-development of the social brain in autism may be mediated in part by mechanisms that lead to physically enhanced yet psychologically under-developed attachment to the mother, and affective-psychotic conditions, such as schizophrenia and depression, may be mediated in part by forms of insecure attachment and by increased relative effects of the maternal brain, both directly from mothers and via imprinted-gene effects in offspring. These hypotheses are concordant with findings from epidemiology, attachment theory, psychiatry, and genetic and epigenetic analyses of risk factors for autism and affective-psychotic conditions, they make novel predictions for explaining the causes of psychosis in Prader-Willi syndrome and idiopathic schizophrenia, and they suggest avenues for therapeutic interventions based on normalizing alterations to epigenetic networks and targeting public-health interventions towards reduction of perturbations to the development of secure attachment in early childhood and individuation during adolescence.

First principles of Hamiltonian medicine

“…As the placenta and breast provide energetic resources to the developing offspring, psychological interactions, especially with the mother, provide cognitive and emotional resources that support early childhood psychological development, with lifelong impacts on psychological health and well-being. John Bowlby's concept of attachment-child psychological bonding that promotes optimal development of social cognition and emotion-serves as a primary construct and metric for understanding mother-offspring interactions and their consequences [113,114]. Child attachment may be (i) secure, such that the child develops an ongoing expectation of investment from the mother, or insecure, either (ii) anxious-insecure, whereby children suffering unmet solicitation of needs express increased distress and contact-seeking, combined with anger and ambivalence or (iii) avoidant-insecure, whereby children with unsatisfied expectations come to avoid and reject carers [115].…”

“…Child attachment may be (i) secure, such that the child develops an ongoing expectation of investment from the mother, or insecure, either (ii) anxious-insecure, whereby children suffering unmet solicitation of needs express increased distress and contact-seeking, combined with anger and ambivalence or (iii) avoidant-insecure, whereby children with unsatisfied expectations come to avoid and reject carers [115]. The former category can be interpreted as active attempts to improve a suboptimal situation for the child, whereas the latter may represent behaviour designed to avoid making a bad situation worse [114,116]. Despite the fact that such insecure attachment is strongly associated with a broad set of psychological and psychiatric disorders [117,118], its incidence is remarkably high, on the order of one-third of children [119].…”

“…These considerations also apply to behavioural and psychological investment, especially in humans for whom early social-brain development assumes paramount importance for mental health. For any given mother-offspring dyad, child psychological health in the context of attachment should thus be some function of the matching between child solicitation and maternal supply, and the resulting levels of maternal investment combined with its effectiveness [114].…”

“…Moreover, the proximate mechanisms should involve conflictual inclusive-fitness effects, and the direction and magnitude of such perturbations should be directly and causally connected with specific psychological and psychiatric health outcomes. For a child, paternal biases in brain imprinted-gene expression are thus predicted to be associated with over-solicitation; by contrast, maternal biases should be associated with reduced solicitation [114]. How well are these expectations met?…”

“…In adulthood, a high proportion of individuals with Prader-Willi syndrome also develop forms of schizophrenia or affective psychosis (psychosis that includes depression), making it among the most penetrant causes of psychotic-affective conditions [134]; moreover, insecure childhood attachment is strongly associated with other psychotic-affective conditions, including schizophrenia [117]. The causal links between insecure attachment and psychotic-affective conditions require further study, but they may include under-development of the hypothalamiccentred, limbic 'paternal brain' relative to the neocortical, mentalistic 'maternal brain' [135], as well as childhood neglect, maltreatment and abuse that dysregulate cognitive-affective development [114,117,118].…”