Högskolan i Skövde

This bachelor’s thesis examines the structural integrity of white matter in medication-naïve individuals with ADHD using diffusion tensor imaging (DTI). It synthesises findings from three recent empirical studies, covering both paediatric and adult populations. Together, these studies involved 186 individuals diagnosed with ADHD and 128 typically developing controls, matched for age, sex, IQ and handedness. The primary DTI metrics analysed were fractional anisotropy (FA), radial diffusivity (RD) and mean diffusivity (MD). In children, one study reported reduced FA in long-range tracts involved in attention and emotion regulation, with RD increases indicating compromised myelin. Another identified sex-specific difference in callosal fibre tracts, with more widespread disruptions in females, although only one finding remained statistically significant after correction for multiple comparisons. In adults, reduced FA in corticothalamic tracts correlated with increased response time variability. These tract-specific white matter alterations appear consistent across age groups, although the affected regions differ in each group. Strengths, limitations and societal implications, including diagnostic accuracy, personal autonomy and access, are critically discussed. Furthermore, this review suggests that atypical white matter organisation is a meaningful and developmentally variable feature of ADHD, independent of medication effects.