Cerebral infarction, as the result of atheroma in large blood vessels, was one of the first explanations for dementia in older people. However, this was a relatively uncommon finding in those presenting with dementia and it was soon realized that subcortical infarctions due to non-atheromatous changes in small blood vessel walls were more important factors in cognitive decline. Furthermore, small vessel disease (SVD) producing lacunar infarcts (LI) and white matter changes increased dementia severity in individuals with only moderate Alzheimer's disease (AD) pathology. Magnetic resonance imaging (MRI) found subcortical (lacunar) 'silent infarcts' and white matter changes were surrogate markers for SVD and increased significantly the likelihood of developing dementia. Detailed histopathological studies of SVD showed it was in fact a range of pathologies, but the aetiology of the most common type (arteriosclerosis/lipohyalinosis) is difficult to explain. Theories to explain SVD include effects of hypertension, a leaky blood-brain barrier (BBB), amyloid accumulation, microbleeds, venous changes and endothelial inflammation. Endothelial expressed inflammatory molecules could represent potential biomarkers of SVD. Many of the risk factors associated with SVD are also present in AD, such as diabetes, systemic hypertension and ageing; all of these can target the endothelium with the potential to initiate SVD, resulting in ischaemic changes and neurodegeneration, including AD pathology.
SUMMARY Intracranial tuberculoma has become a rarity. It remains a curable lesion that responds well to medical therapy. Although diagnosis in developed countries is often made only postoperatively, early and effective treatment can be instituted if a high index of suspicion is maintained and diagnostic criteria are looked for. A case is presented which illustrates the difficulties in reaching a diagnosis, and a review of the literature is given.
SummaryAn important protective function of the brain's innate immune system is to detect the presence of proteins such as amyloid and to remove them before they become neurotoxic, as is thought to occur in Alzheimer's disease (AD). Ageing affects the immune system response to infection and can influence the systemic response to vaccination and other potential immunotherapeutic agents. The generation of systemic antibodies is a vital component of the immune response, facilitating the identification and clearance of pathogens from the central nervous system (CNS). Experimental evidence using transgenic animal models of AD has shown successful clearance of amyloid from the CNS following vaccination with an amyloid peptide, and consequently a trial of amyloid beta peptide (Aβ) vaccination was undertaken in older people with AD. This produced some unexpected results, as not only was there evidence for amyloid plaque removal, but also a small number of cases developed encephalitis. A detailed review of the response to vaccination and the neuropathology findings are discussed, showing that the findings are understandable given the effects of ageing upon the innate immune system in the brain. Finally, the therapeutic potential of manipulating the regulatory components of the ageing innate immune system in order to inhibit brain inflammation and reduce cognitive decline is outlined.
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