**Review of Current Neuroimaging Studies of the Effects of Prenatal Drug Exposure: Brain Structure and Function**

Jennifer Willford, Conner Smith, Tyler Kuhn, Brady Weber and Gale Richardson

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/63389

#### **Abstract**

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Neuroimaging tools have provided novel methods for understanding the impact of prenatal drug exposure on brain structure and function and its relation to develop‐ ment and behavior. Information gained from neuroimaging studies allows for the investigation of how prenatal drug exposure alters the typical developmental trajecto‐ ry. The current prevalence and characteristics of prenatal drug exposure and its implications for vulnerable periods of brain development are reviewed. Structural and functional neuroimaging methods are introduced with examples of how study results from prenatal alcohol, cocaine, marijuana, and tobacco exposure further our under‐ standing of the neurodevelopment impact of prenatal drug exposure. Prenatal drug neuroimaging studies have advanced our understanding of mechanisms and function‐ al deficits associated with prenatal drug exposure. Studies have identified brain circuits associated with the default mode network, inhibitory control, and working memory that show differences in function as a result of prenatal drug exposure. The informa‐ tion gained from studies of prenatal drug exposure on brain structure and function can be used to make connections between animal models and human studies of prenatal drug exposure, identify biomarkers of documented effects of prenatal drug exposure on behavior, and inform prevention and intervention programs for young children.

**Keywords:** fMRI, prenatal substance exposure, alcohol, cocaine, marijuana, tobacco

### **1. Introduction**

This chapter begins with a review of issues surrounding the assessment of the impact of prenatal drug exposure on developmental outcomes in children followed by a brief update of

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current trends in prenatal drug exposure including the prevalence, patterns, and characteris‐ tics of prenatal drug use, including alcohol, tobacco, marijuana, and other illicit drugs. Then, the impact of current neuroimaging methodology on our understanding of the effects of prenatal drug exposure is explored. The review considers examples of how neuroimaging tools have increased our understanding of the often subtle and complex impact of prenatal substance exposure on child brain development and behavior. The impact of prenatal drug exposure is challenging to assess due to characteristics of maternal drug use such as poly‐ drug exposure and differences in the purity and legality of drugs. Developmental outcomes associated with prenatal drug exposure will also be affected by the timing, dose, and pat‐ tern of drug use during pregnancy, and the varying impact of other environmental factors such as maternal health and nutrition, access to prenatal care, and the home environment [1, 2]. For over 40 years, the impact of prenatal drug exposure has been studied in relation to growth, behavior, and cognitive outcomes using both longitudinal and cross-sectional designs, which have provided a depth of understanding. Overall, the most important outcome of decades of research has been that no safe levels of any type of prenatal drug use during pregnancy have been identified. Furthermore, the impact of prenatal drug exposure is often subtle and combined with other environmental risk factors, contributes to poor developmen‐ tal outcomes for young children and adolescents.
