Neurologic soft signs and low birthweight: their association and neuropsychiatric implications.

BACKGROUND: We examine the relationship between neurologic soft signs and cognitive deficits, learning disorders, and psychiatric problems in low birthweight (LBW) and normal birthweight (NBW) children.
METHODS: Representative samples of LBW and NBW children were selected from the 1983-1985 newborn discharges of two major hospitals in Michigan. Eight hundred-twenty three children (75% of the target sample) were evaluated at ages 6 and 11. A standardized neurologic evaluation was used by neurologists to measure neurologic soft signs at age 6 (children with frank neurologic impairment were excluded). IQ was measured by WISC-R and behavior problem lists were rated by mothers and teachers. Standard tests of academic achievement were used to identify learning disorders. All assessments were blind to LBW status. Using multiple regression analysis, applying generalized estimating equations (GEE), we estimated the effects of soft signs on 3 behavioral domains, based on information from multiple informants and times of assessment.
RESULTS: LBW was associated with a two-fold increased risk for soft signs. Soft signs increased the risk for subnormal IQ and for learning disorders in children with normal IQ. Soft signs were associated with excess internalizing problems in LBW and NBW children, and with attention and externalizing problems in LBW children; the excess in externalizing problems in LBW children was observed only at age 6.
CONCLUSIONS: Soft signs are a marker of high risk for cognitive and psychiatric problems. Of particular concern is their presence in LBW children, in whom they are associated with more severe cognitive deficits and more pervasive psychiatric problems.