Diffusion tensor imaging studies in late-life depression: systematic review and meta-analysis

Area of Science:

• Neuroimaging
• Geriatric Psychiatry
• Neurology

Background:

• Late-life depression (LLD) is associated with increased cerebrovascular risks and white matter abnormalities.
• Diffusion tensor imaging (DTI) is a key technique for assessing white matter integrity.

Purpose of the Study:

• To systematically review and meta-analyze DTI studies investigating white matter alterations in LLD.
• To identify specific white matter tracts affected in LLD.

Main Methods:

• Systematic search of major scientific databases (MEDLINE, EMBASE, PsycINFO, PubMed, Google Scholar).
• Inclusion of DTI studies comparing LLD patients with healthy controls.
• Meta-analysis of fractional anisotropy (FA) values in key brain regions.

Main Results:

• Fifteen studies were included in the review; nine were used for meta-analysis.
• LLD patients exhibited significantly lower FA in the dorsolateral prefrontal cortex (DLPFC) and uncinate fasciculus (UF) compared to controls.
• A large effect size was noted for DLPFC, and a medium effect size for UF, with some heterogeneity and publication bias in DLPFC findings.

Conclusions:

• DTI studies consistently demonstrate reduced white matter integrity in the DLPFC and UF in individuals with LLD.
• These affected regions are integral to frontostriatal and limbic networks.
• Disruption of frontal and fronto-limbic white matter tracts likely contributes to the pathophysiology of LLD.