Thalamic abnormalities in older adults with early‐onset depression using structural magnetic resonance imaging

Background The thalamus is a key diencephalic structure involved in major depressive disorder (MDD). In particular, studies have consistently revealed abnormalities in thalamic volumes in older adults with late‐onset depression (LOD). However, similar abnormalities in older adults with early‐onset depression (EOD) have not been well studied. Method Fifty‐nine euthymic participants with a history of EOD and fifty‐nine matched comparison participants without a lifetime history of depression underwent neuroimaging, medical and neuropsychological assessments. Thalamic volumes were compared between groups. Due to the right hemispheric (RH) dominance theory of MDD, we explored both bilateral and right hemispheric thalamic volumes. Multiple regression analyses were used to evaluate between‐group and within‐group effects. A correlational analysis examined associations between group and cognitive performance. Result Relative to the comparison group, those with EOD had significantly larger bilateral and RH thalamic volumes. Those with EOD, those who were younger, and those who had fewer years of education, demonstrated larger bilateral thalamic volumes. When split by group (EOD vs comparison group), only age remained significantly different for those with EOD. For RH volumes, those with EOD and those who were younger demonstrated larger RH thalamic volumes. When split by group, the results showed that age only was significant for both groups. No significant correlations were found between cognitive performance and EOD groups. Conclusion Older adults with a history of EOD showed significantly larger bilateral and RH thalamic volumes. Further research is needed to further elucidate the underlying mechanism of this change.