Birgitte Klee Burton, PhD

New research indicates motor impairment as a child could be a risk factor for mental illnesses.

A team, led by Birgitte Klee Burton, PhD, Child and Adolescent Mental Health Centre, Mental Health Services Capital Region, Research Unit, Copenhagen University Hospital, assessed motor development and its association with psychotic experiences in children with familial high risk (FHR) of schizophrenia or bipolar disorder compared to a control group.

Motor Impairments

Motor abnormalities can be a component of psychotic illness, but they are not only a proxy of altered neurodevelopment but also can be related to psychotic risk.

In the prospective longitudinal cohort trial dubbed the Danish High Risk and Resilience Study, the investigators used data from 437children born in Denmark between Sept. 1, 2004 and Aug. 31, 2009 with no, 1, or 2 parents born in Denmark with schizophrenia or bipolar disorder.

The mean age of the patient population was 11.99 years.

The investigators then matched children with no biological parent diagnosed with schizophrenia spectrum disorder or bipolar disorder were matched to children with familial high risk of schizophrenia on the basis of sex, age, and municipality.Participants with familial high risk of bipolar disorder were included as a non-matched group.

The investigators assessed motor function in participants with familial high risk of schizophrenia, pediatric patients with familial high risk of bipolar disorder, and children in the control group at approximately age 8 and age 12 using the Movement Assessment Battery for Children—Second Edition (Movement ABC-2).

They also assessed psychotic experiences using the psychosis section of the Kiddie Schedule for Affective Disorders and Schizophrenia for School-Age Children—Present and Lifetime Versions.

Raters were masked regarding familial risk status and motor development was assessed from baseline to follow-up in the different groups using a linear mixed model.

Finally, they examined the relationship between definite motor problems and psychotic experiences using logistic regression.

Familial High Risk

The results show children with familial high risk of schizophrenia showed stable motor development deficits in manual dexterity (difference in intercept, –1.62; 95% CI, –2.39 to –0.85; P <0.0001; difference in slope, 0.17; 95% CI, –0.48 to 0.81; P = 0.61) and balance (difference in intercept, –1.58; 95% CI, –2.34 to –0.82; P <0.0001; difference in slope, 0.32; 95% CI, –0.34 to 0.99; P = 0.34), and a developmental lag in aiming and catching (difference in slope, –1.07; 95% CI, –1.72 to –0.41; P = 0.0015; difference in intercept, –0.59; 95% CI, –1.35 to 0.17; P = 0.13) compared with controls.

Children with familial high risk of bipolar disorder had no motor developmental differences on a group basis, while children with familial high risk of schizophrenia were more likely to have definite motor problems (OR, 2.86; 95% CI, 1.60 to 5.11; P = 0.0004). The same was true for children with familial high risk of bipolar disorder (OR, 2.45; 95% CI, 1.28-4.70; P = 0.0068).

Participants with definite motor problems across all groups were more likely to have psychotic experiences compared to children with no definite motor problems (OR, 1.90; 95% CI 1.12-3.21; P = 0.017).

“Clinicians should be aware that motor impairment in childhood can reflect neurodevelopmental vulnerability to psychosis,” the authors wrote. “Our findings contribute to the identification of early risk markers for severe mental illness, both for use by clinicians and for establishing a basis for future primary preventive intervention studies in the premorbid phase.”

The study, “Impaired motor development in children with familial high risk of schizophrenia or bipolar disorder and the association with psychotic experiences: a 4-year Danish observational follow-up study,” was published online in The Lancet Psychiatry.