It is premature to conclude that these findings are definitive METH effects, given the small sample sizes and the potential confounds of uncontrolled drug exposures, medical and socio-demographic conditions. For instance, as summarized below, there is accumulating evidence that prenatal nicotine exposure in and of itself may be related to structural changes in the developing brain35, 98, and prenatal alcohol exposure has been clearly linked to a wide range of neurostructural alterations99. The further problem of differentiating actual causal processes from epiphenomena and compensatory responses is also present in these cross-sectionally designed studies100. Nevertheless, these studies suggest that subcortical brain structures and prefrontal-striatal circuitry involved in attention and memory101-103 may be impacted adversely by the neurotoxic effects of METH on developing neural systems.
