The longitudinal association of combined regulatory problems in infancy and mental health outcome in early childhood: a systematic review

Co-occurring regulatory problems in infancy, RPs, including excessive crying, feeding-eating and sleeping, have been found associated with mental health problems in school ages. Still, an overview is needed on trajectories of co-occurring or combined RPs, and mental health problems in early childhood. The aim of this review is to systematically review the literature on longitudinal community-based studies of combined RPs measuring mental health outcomes in early childhood. Following the PRISMA guideline, we systematically reviewed the literature published 2000-2020, in which combined RPs are assessed in infancy, and mental health is examined using standardised measures at ages 1-7 years. The search was performed in four databases MEDLINE, EMBASE, PsycINFO and Scopus. A protocol is published on PROSPERO. Based on 1978 screened articles, 42 papers were screened for eligibility, of which six were included, comprising data on two or more RPs investigated among a total of 20,675 children. Assessment of risk of bias in the studies showed overall good quality in five of the six papers. The literature reviewed suggests that combined RPs in infancy are early markers of mental health problems during early childhood, and highlights that community studies exploring the longitudinal associations of combined RP and mental health problems in preschool and early school age are still scarce. Overall, the review points to the need of research into preventive intervention targeting early manifestations of childhood dysregulation, such as RPs.