There is growing awareness that infections may contribute to the development of senile dementia including Alzheimer’s disease (AD), and that immunopotentiation is therefore a legitimate target in the management of diseases of the elderly including AD. In Part I of this work, we provided a historical and molecular background to how vaccines, adjuvants, and their component molecules can elicit broad-spectrum protective effects against diverse agents, culminating in the development of the tuberculosis vaccine strain Bacille Calmette–Guérin (BCG) as a treatment for some types of cancer as well as a prophylactic against infections of the elderly such as pneumonia. In Part II, we critically review studies that BCG and other vaccines may offer a measure of protection against dementia development. Five studies to date have determined that intravesicular BCG administration, the standard of care for bladder cancer, is followed by a mean ∼45% reduction in subsequent AD development in these patients. Although this could potentially be ascribed to confounding factors, the finding that other routine vaccines such as against shingles (herpes zoster virus) and influenza (influenza A virus), among others, also offer a degree of protection against AD (mean 29% over multiple studies) underlines the plausibility that the protective effects are real. We highlight clinical trials that are planned or underway and discuss whether BCG could be replaced by key components of the mycobacterial cell wall such as muramyl dipeptide. We conclude that BCG and similar agents merit far wider consideration as prophylactic agents against dementia.

中文翻译：

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疫苗和痴呆症：第二部分。卡介苗和其他疫苗对抗痴呆症的功效

人们越来越认识到，感染可能会导致包括阿尔茨海默病 (AD) 在内的老年痴呆症的发生，因此免疫增强是治疗包括 AD 在内的老年人疾病的合理目标。在这项工作的第一部分中，我们提供了疫苗、佐剂及其组成分子如何对多种药物产生广谱保护作用的历史和分子背景，最终开发了结核病疫苗株卡介苗（BCG） ）作为某些类型癌症的治疗方法以及预防老年人感染（例如肺炎）的方法。在第二部分中，我们批判性地回顾了卡介苗和其他疫苗可能提供预防痴呆症发展的措施的研究。迄今为止的五项研究已确定，膀胱内注射 BCG（膀胱癌的护理标准）后，这些患者随后的 AD 发展平均减少约 45%。尽管这可能归因于混杂因素，但研究发现其他常规疫苗，如带状疱疹（带状疱疹病毒）和流感（甲型流感病毒）等，也能提供一定程度的 AD 保护（平均为 29%）研究）强调了保护作用确实存在的合理性。我们重点介绍计划中或正在进行的临床试验，并讨论 BCG 是否可以被分枝杆菌细胞壁的关键成分（如胞壁酰二肽）取代。我们的结论是，卡介苗和类似药物作为痴呆症的预防药物值得更广泛的考虑。