November 09, 2016
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Prenatal exposure to methamphetamine and tobacco delays motor development

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Infants prenatally exposed to methamphetamine and tobacco exhibited delays in motor development, particularly males; however, delays may normalize by age 3 to 4 months, according to recent findings.

“In the United States, the prevalence of pregnant women seeking treatment for methamphetamine use disorder increased from 8% to 24% between 1994 and 2006, while treatment for cocaine, alcohol, and tobacco declined. This trend will likely continue owing to the steady incidence of methamphetamine use between 2002 and 2013 and because twice as many women of childbearing age sought treatment for methamphetamine use disorder compared with men,” Linda Chang, MD, MS, of University of Hawaii at Manoa, Honolulu, and colleagues wrote. “Although 70% to 90% of methamphetamine users smoke tobacco cigarettes concurrently, the effect of comorbid methamphetamine and tobacco use during pregnancy on fetal brain development is rarely studied.”

To determine if microstructural brain abnormalities in children with prenatal methamphetamine and/or tobacco exposure are present at birth prior to environmental effects, researchers conducted a prospective, longitudinal study of 139 infant-mother dyads. Of these, 36 were exposed to methamphetamine/tobacco, 32 were exposed to tobacco and 71 were unexposed. The mean postmenstrual age at baseline was 41.5 weeks.

Infants exposed to methamphetamine/tobacco exhibited delayed development on active muscle tone (P < .001) and total neurologic scores (P = .01) that normalized by age 3 to 4 months.

Only male infants exposed to methamphetamine/tobacco had lower fractional anisotropy (P = .02) and higher diffusivities in superior (P = .002) and posterior corona radiatae (P = .01) at baseline that normalized by age 3 months.

Fractional anisotropy was persistently lower in the anterior corona radiata only in female infants exposed to methamphetamine/tobacco (P = .04) or tobacco (P = .01).

Infants exposed to tobacco exhibited persistently lower axial diffusion in the thalamus and internal capsule across groups (P = .02).

“This case-control study confirms that prenatal exposure to methamphetamine and/or tobacco alters white matter developmental trajectories, and the effects are partly dependent on sex... The key finding may thus be that of lower axial diffusivity in tobacco-exposed infants regardless of sex, which is similar to what is seen in alcohol-exposed infants during the first month of life Annerine Roos, PhD, of Stellenbosch University, Cape Town, South Africa, and Kirsten Ann Donald, MD, PhD, of University of Cape Town, wrote in an accompanying editorial. “Nevertheless, improved imaging methods and post-processing software, including better motion correction and using diffusion data to investigate connectivity networks of the brain, may help us get closer to finding biomarkers and determining their relevant clinical applications.” – by Amanda Oldt

Disclosure: The researchers report no relevant financial disclosures.