Interaction Between Parental Psychosis and Early Motor Development and the Risk of Schizophrenia in a General Population Birth Cohort

Abstract

BackgroundDelayed motor development in infancy and family history of psychosis are both associated with increased risk of schizophrenia, but their interaction is largely unstudied.AimTo investigate the association of the age of achieving motor milestones and parental psychosis and their interaction in respect to risk of schizophrenia.MethodsWe used data from the general population-based prospective Northern Finland Birth Cohort 1966 (n = 10,283). Developmental information of the cohort members was gathered during regular visits to Finnish child welfare clinics. Several registers were used to determine the diagnosis of schizophrenia among the cohort members and psychosis among the parents. Altogether 152 (1.5%) individuals had schizophrenia by the age of 46 years, with 23 (15.1%) of them having a parent with psychosis. Cox regression analysis was used in analyses.ResultsParental psychosis was associated (P < 0.05) with later achievement of holding the head up, grabbing an object, and walking without support. In the parental psychosis group, the risk for schizophrenia was increased if holding the head up (hazard ratio [HR]: 2.46; degrees of freedom [df] = 1; 95% confidence interval [95% CI]: 1.07–5.66) and touching the thumb with the index finger (HR: 1.84; df = 1; 95% CI: 1.11–3.06) was later. In the group without parental psychosis, a delay in the following milestones increased the risk of schizophrenia: standing without support and walking without support. Parental psychosis had an interaction with delayed touching thumb with index finger (HR: 1.87; df = 1; 95% CI: 1.08–3.25) when risk of schizophrenia was investigated.ConclusionsParental psychosis was associated with achieving motor milestones later in infancy, particularly the milestones that appear early in a child's life. Parental psychosis and touching the thumb with the index finger had a significant interaction on risk of schizophrenia. Genetic risk for psychosis may interact with delayed development to raise future risk of schizophrenia, or delayed development may be a marker of other risk processes that interact with genetic liability to cause later schizophrenia.

Prognosis of schizophrenia spectrum disorder may not be predetermined during early development – the Northern Finland Birth Cohort 1966

“…Early parenthood-related and developmental risk factors of schizophrenia (Keskinen et al, 2013;Keskinen et al, 2015) did not predict later outcomes of illness, with the exception of young maternal age. Based on our study, the prognosis of SSD may not be predetermined in early development, and this highlights even more the importance of effective, individualized treatments.…”

“…Early parenthood-related and developmental factors and their classifications were based on earlier literature to present factors that increase the risk of schizophrenia (Keskinen et al, 2013;Keskinen et al, 2015).…”

“…The age of achievement of standing up, standing up without support and walking without support was examined in months as a continuous variable (Keskinen et al, 2015) and information was gathered from regular visits to Finnish child welfare clinics (Pillas et al, 2014).…”

“…register-based employment and hospitalization outcomes) in schizophrenia spectrum disorder (SSD) in years after the illness onset and to compare the results with individuals without SSD. The analysed variables were same factors, such as high maternal age, unwantedness of the pregnancy, grand multiparity, parental psychosis, high weight and low height at birth, and later achievement of standing up and standing and walking without support that increased the risk of schizophrenia in this same birth cohort sample until the ages of 44 (Keskinen et al, 2013) and 46 years (Keskinen et al, 2015). We hypothesized that early parenthood-related and developmental risk factors are related to a lower level of employment and a higher level of hospitalization at midlife among those with SSD.…”

Altered growth trajectory of head circumference during infancy and schizophrenia in a National Birth Cohort

“…Small HC was related to an increased risk of later schizophrenia, independent of other factors (Cantor-Graae et al, 1998; Hultman et al, 1997) though other studies found no association, or relationships that were restricted to females (Wahlbeck et al, 2001; Welham et al, 2009). However, in contrast to other indices of development which delineate trajectories, including developmental milestones, neurocognition, and behavior prior to schizophrenia onset (Cannon et al, 1997; Isohanni et al, 2004; Keskinen et al, 2015; Khandaker et al, 2011), the pattern of HC growth among pre-schizophrenia cases following birth has not been well investigated because those studies utilized measures of HC that were isolated to birth. Growth trajectory of HC can more optimally be studied by examining growth velocity, which is defined as the rate of change in HC per unit change in time.…”