Perivascular deposits of serum proteins in cerebral cortex in vascular dementia

Immunocytochemical techniques were used to study the histopathologic changes in vascular dementia, i. e., both multi-infarct dementia (MID) and MID combined with Alzheimer changes (MID/SDAT). In eight of 13 of the dementia cases strongly immunostained deposits of plasma proteins were observed around numerous capillaries of layers I-IV of frontal grey matter. Each of these deposits contained albumin, prealbumin, IgG, C1q, C3c, and fibrinogen. No such deposits were found in any of the seven non-demented aged controls. In contrast, in white matter in both demented and normal aged control cases only weak immunostaining of serum proteins was observed which gradually decreased with the distance from the vessels. The presence of heavy deposits of serum proteins exclusively around the capillaries of the gray matter in cases with vascular dementia may indicate a defect of the cortical capillary system which might play a role in the clinical symptoms seen in vascular dementia. The enrichment of C1q within the deposits is intriguing as this might occur because of the binding of C1 through its subunit C1q to the antibody-antigen complex and thereby support a possible immunologic involvement in the formation of these deposits.