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Background: The "vascular depression" hypothesis has sought to explain differences in etiology between early and late life depression, and has been reinforced by recent imaging and morphometric studies. Gamma-aminobutyric acid (GABA) is thought to play a major role in the neurobiology of depression. However, it is unclear whether there is an effect on GABA neuronal subpopulations in an elderly depressed cohort. This study therefore examined immunohistochemically two calcium-binding proteins, calretinin and parvalbumin, which have been demonstrated to bind to two distinct GABAergic interneuron subpopulations, within the dorsolateral prefrontal cortex (DLPFC) of elderly depressed patients, against age-matched controls.Methods: Post-mortem tissue was obtained from nine controls and 11 depressed patients for the parvalbumin study and seven controls and 14 depressed patients in the calretinin study, and the mean percentage per area of immunohistochemical staining of the two antibodies was measured in individual layers and across the whole of the DLPFC.Results: The study found a reduction in parvalbumin immunostaining in layer 6 (p = 0.05) of the DLFPC in elderly depressed patients. However, no significant changes were found in parvalbumin or calretinin immunostaining in the any other layer of the DLPFC in elderly depressed patients.Conclusion: The study does not suggest any change in GABA interneuron subpopulations, though significant reductions in layer 6 may represent subtle disturbance in GABA parvalbumin-expressing interneuron and glumatatergic pyramidal projection neuron regulation in late-life depression. [ABSTRACT FROM AUTHOR]

Background: The orbitofrontal cortex has been implicated as a key component in depression by several imaging studies. This study aims to examine morphometrically glial cell and neuronal density and neuronal volume in the orbitofrontal cortex of late-life major depression patients.Methods: Post mortem tissue from 13 patients with major depression and 11 matched controls was obtained and analyzed using the optical disector and nucleator methods.Results: No changes were found in glial cell, pyramidal or non-pyramidal neuron density, or in non-pyramidal and pyramidal neuron volume in the orbitofrontal cortex.Conclusions: Based on previous findings, this study suggests variability in morphological changes within the orbitofrontal cortex, as well as the prefrontal cortex as a whole. [ABSTRACT FROM PUBLISHER]

Background: Neuroimaging studies have revealed structural and functional changes in brain regions associated with major depressive disorder (MDD). These abnormalities appear to be more common and extensive in patients with late-life depression than in younger patients. It has therefore been hypothesized that different morphometric and pathological changes may be associated with MDD, depending on age. Methods: This review stratifies the findings of the various studies on cell morphology in MDD according to age and assesses any possible differences in neuronal and glial cell changes in younger and older age groups. Results: Recent morphological studies in postmortem tissue have revealed alterations in neuron and glial cell populations in the frontal and subcortical circuitry associated with depression. These may differ by age, with glial reduction consistently reported in younger groups in cortical areas and neuronal changes identified in studies with older subjects. Conclusions: Apparent differences in the morphological changes between younger and elderly patients may suggest a differing pathological basis in MDD, dependent on age. [ABSTRACT FROM AUTHOR]

Background: Late-life depression has been associated with cerebrovascular disease and especially with ischaemic white matter hyperintensities on magnetic resonance imaging. Neuroimaging and morphometric studies have identified abnormalities in the dorsolateral prefrontal cortex.Aims: To examine glial and neuronal density and neuronal volume in the dorsolateral prefrontal cortex in late-life major depression.Method: We used the disector and nucleator methods to estimate neuronal density and volume and glial density of cells in the dorsolateral prefrontal cortex in a post-mortem study of 17 individuals with late-life major depression and 10 age-matched controls.Results: We found a reduction in the volume of pyramidal neurones in the whole cortex, which was also present in layer 3 and more markedly in layer 5. There were no comparable changes in non-pyramidal neurones and no glial differences.Conclusions: Overall, we found a decrease in pyramidal neuronal size in the dorsolateral prefrontal cortex in late-life depression. [ABSTRACT FROM AUTHOR]