Reductions in neuronal density in elderly depressed are region specific

Area of Science:

• Neuroscience
• Geriatric Psychiatry
• Neuropathology

Background:

• Frontal regions, including the orbitofrontal cortex (ORB) and dorsolateral prefrontal cortex (dlPFC), are implicated in geriatric depression neuropathology.
• Previous studies reported reduced pyramidal neuron density in the ORB of older depressed subjects.
• The cellular pathology of the dlPFC in geriatric depression remained unexamined.

Purpose of the Study:

• To investigate the cellular pathology of the dorsolateral prefrontal cortex (dlPFC) in elderly individuals with major depression.
• To compare neuronal density and cortical width in the dlPFC between depressed elderly subjects and age-matched controls.

Main Methods:

• Postmortem dlPFC (Brodmann's area 9) tissue was obtained from 10 older depressed subjects and 10 controls.
• Pyramidal and non-pyramidal neuron density (overall and laminar) was measured using the linear optical disector method.
• Cortical and laminar widths were also assessed.

Main Results:

• No significant differences were found in the overall or laminar density of pyramidal or non-pyramidal neurons between depressed and control groups.
• Cortical and laminar widths in the dlPFC were not significantly affected by depression in the elderly.
• These findings contrast with previous observations of reduced pyramidal neuron density in the ORB.

Conclusions:

• Neuronal pathology in geriatric depression appears to be region-specific.
• The dlPFC does not show significant changes in neuronal density in elderly depressed individuals.
• These results highlight the need for further research into regional variations in brain pathology in geriatric depression.