Microstructural white matter abnormalities and remission of geriatric depression

Area of Science:

• Neuroimaging
• Geriatric Psychiatry
• Neuroscience

Background:

• White matter abnormalities can disrupt limbic-cortical balance, potentially leading to chronic depression.
• Geriatric depression is often linked to complex neurobiological factors affecting mood regulation.

Purpose of the Study:

• To investigate if microstructural white matter abnormalities in cortico-striato-limbic networks are associated with treatment resistance in geriatric depression.
• To test the hypothesis using diffusion tensor imaging (DTI) in elderly patients with major depression.

Main Methods:

• Nondemented individuals with major depression underwent a placebo period, followed by 12 weeks of escitalopram treatment.
• Remission was defined as a Hamilton Depression Rating Scale (HAM-D) score ≤7 for two consecutive weeks.
• Diffusion tensor imaging (DTI) and voxel-based analysis of fractional anisotropy (FA) were performed, with age as a covariate.

Main Results:

• Non-remitted patients (N=23) exhibited lower fractional anisotropy (FA) in frontal limbic areas, including the anterior cingulate and prefrontal cortex.
• Reduced FA was also observed in the genu of the corpus callosum, perihippocampal white matter, posterior cingulate cortex, and insular white matter.
• Further reductions in FA were found in the neostriatum, midbrain, and select temporal and parietal regions compared to remitted patients (N=25).

Conclusions:

• Lower fractional anisotropy in widespread cerebral networks correlates with poor response to antidepressants in geriatric depression.
• These white matter alterations may represent a neuroanatomical substrate contributing to treatment resistance in this population.