Academic journal article Hong Kong Journal of Psychiatry

Testing the Vascular Depression Hypothesis: Comparison of Magnetic Resonance Imaging Features in Elderly Patients with Depression

Academic journal article Hong Kong Journal of Psychiatry

Testing the Vascular Depression Hypothesis: Comparison of Magnetic Resonance Imaging Features in Elderly Patients with Depression

Article excerpt

Abstract

Objective: A subcategory of depression in elderly people, termed vascular depression, has previously been proposed. This study tests one hypothesis of this proposal, the association between the presence of white matter hyperintensities seen on magnetic resonance imaging and clinical symptoms characteristic of vascular depression.

Patients and Methods: Ten consecutive patients referred to an old age psychiatry unit, older than 65 years and meeting the International Classification of Diseases-10 criteria for depression, were screened for symptoms of vascular depression. Clinical ratings of 'classical' depressive symptoms and physical morbidity were also completed. The intensity of white matter hyperintensities on magnetic resonance imaging for each patient was blindly rated by a consultant radiologist.

Results: The severity of vascular depression symptoms was positively correlated with the severity of white matter hyperintensities. White matter hyperintensity severity was not correlated with age, gender, or physical morbidity. The mean severity of white matter hyperintensities was significantly greater in the vascular depression subgroup compared with the 'classical' depression subgroup.

Conclusions: A subcategory of depression in the elderly, vascular depression, is associated with increased severity of white matter hyperintensities seen on magnetic resonance imaging. This subcategory can be defined purely on the grounds of clinical symptoms. Key words: Depression, Pathology, Vascular factors

Introduction

It has been nearly a quarter of a century since Robinson et al demonstrated a possible association between vascular pathology in the brain and depression using both animal models (1) and case studies. (2) Although Robinson et al's original proposition, that left hemisphere strokes cause depression, has not stood the test of time, (3) interest in the concept of 'vascular depression' has grown.

The association has been demonstrated in both directions, with depressed outpatients appearing to show higher rates of hypertension, (4) while patients suffering coronary artery disease show higher rates of depression. (5) Baldwin has suggested that late-onset depression in particular is associated with vascular risk factors and vascular disease. (6) This subgroup of patients have less genetic susceptibility to depression, (7) and would also be expected to have greater psychological resilience, which focuses interest on possible neuropathological aetiologies.

The advent of magnetic resonance imaging (MRI) and the description of white matter hyperintensities (WMH), or leukoaraiosis, by Hachinski et al (8) has fuelled a contemporary debate as to whether late-onset depression is associated with vascular pathology in the brain. (6) Depressed elderly patients have been shown to have more WMH than non-depressed elderly patients. (9) Late-onset depression may also be associated with greater subcortical hyperintensities in the basal ganglia compared with early-onset depression. (10) Harrel et al found that those depressed patients with the most severe WMH also had significantly lower mini-mental state examination (MMSE) scores compared with those depressed patients with mild WMH. (11) In a review of neuroimaging studies in depression, Soares and Mann have suggested the following clinical correlations to subcortical WMHs: apathy, psychomotor slowing, and poorer response to antidepressant treatment. (12)

Some authors have elaborated on these observations to suggest that a subset of depression in the elderly, termed 'vascular depression', is pathologically related to the presence of WMHs. Krishnan et al have put forward MRIdefined criteria for diagnosing vascular depression, (13) which include a score greater than 2 using the criteria of Fazekas et al, (14) which provides an assessment of the extent of subcortical grey matter, deep white matter, and periventricular changes on brain MRI. …

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