Neurodegenerative conditions share common primary risk factors and mediators of disease progression. Because many degenerative disorders are age related, deteriorating immunity in aging patients might impose additional risk. Adaptive (T-cell-mediated) immunity is a defense mechanism that instructs microglia to fight off and clear away self-derived enemies. Such adaptive immunity can be boosted, without risking the development of autoimmune disease, by injecting weak agonists of self-antigens or by weakening the suppressive CD4+CD25+ regulatory T cells. If widely cross-reactive, the agonist might effectively counteract a variety of neurodegenerative disorders. Boosting of relevant T cells by vaccination could thus 'recharge' a deteriorating immune system that has to contend with an increasing number of risk factors.