State-dependent altered connectivity in late-life depression: a functional near-infrared spectroscopy study

Area of Science:

• Neuroscience
• Gerontology
• Psychiatry

Background:

• Late-life depression is linked to cognitive deficits, worse treatment outcomes, and neurodegenerative disease risk.
• Cognitive impairments in elderly depression are well-documented, but neural processing differences remain unclear.

Purpose of the Study:

• To investigate neural processing and functional connectivity (FC) within the cognitive control network in late-life depression.
• To compare brain activity at rest and during a cognitive task between depressed and non-depressed elderly individuals.

Main Methods:

• Used functional near-infrared spectroscopy (fNIRS) to measure hemodynamic responses in 49 depressed and 51 non-depressed elderly subjects (51-83 years).
• Assessed FC and network metrics at rest and during the Trail Making Test.
• Analyzed differences in FC and network organization between the groups.

Main Results:

• Significant differences in FC were observed between depressed and non-depressed subjects at rest and during task performance.
• Depressed subjects exhibited reduced FC in a left frontopolar network during the task.
• Depressed subjects showed increased FC in a left frontoparietal network at rest.

Conclusions:

• Late-life depression is associated with altered functional connectivity and network organization in the brain.
• Increased resting-state FC in depressed elderly individuals may reflect rumination, potentially impairing executive function during cognitive tasks.