Immunotherapy holds great promise for Alzheimer's disease (AD) and other conformational disorders but certain adverse reactions need to be overcome. The meningoencephalitis observed in the first AD vaccination trial was likely related to excessive cell-mediated immunity caused by the immunogen, amyloid-β (Aβ) 1-42, and the adjuvant, QS-21. To avoid this toxicity, we have been using Aβ derivatives in alum adjuvant that promotes humoral immunity. Other potential side effects of immunotherapy are increased vascular amyloid and associated microhemorrhages that may be related to rapid clearance of parenchymal amyloid. Here, we determined if our immunization strategy was associated with this form of toxicity, and if the therapeutic effect was age-dependent. Tg2576 mice and wild-type littermates were immunized from 11 or 19 months and their behaviour evaluated prior to killing at 24 months. Subsequently, plaque-and vascular-Aβ burden, Aβ levels and associated pathology was assessed. The therapy started at the cusp of amyloidosis reduced cortical Aβ deposit burden by 31% and Aβ levels by 30-37%, which was associated with cognitive improvements. In contrast, treatment from 19 months, when pathology is well established, was not immunogenic and therefore did not reduce Aβ burden or improve cognition. Significantly, the immunotherapy in the 11-24 months treatment group, that reduced Aβ burden, did not increase cerebral bleeding or vascular Aβ deposits in contrast to several Aβ antibody studies. These findings indicate that our approach age-dependently improves cognition and reduces Aβ burden when used with an adjuvant suitable for humans, without increasing vascular Aβ deposits or microhemorrhages.

These findings suggest that COX-2-dependent mechanisms may play a role in the development of POCD. This effect may be dependent on the modulation of glial cell activation.

In the last couple of decades, substantial progress has been made in the development of transgenic mouse models developing amyloid-β deposits and/or neurofibrillary tangles. These mouse models of Alzheimer’s disease and related disorders provide an excellent tool for investigating etiology, pathogenic mechanisms and potential treatments. An essential component of their characterization is a detailed behavioral assessment, which clarifies the functional consequences of these pathologies. We have selected and refined a series of cognitive and sensorimotor tasks that are ideal for studying these models and the efficacy of various treatments.

NIMO reverses the disturbance of short-term working memory caused by moderate hypoxia in mice. The results may have implications for cognitive changes linked to Ca homeostasis in the postoperative period.