The neuropathological correlates of Alzheimer's disease (AD) include amyloid-beta (Abeta) plaques and neurofibrillary tangles. To study the interaction between Abeta and tau and their effect on synaptic function, we derived a triple-transgenic model (3xTg-AD) harboring PS1(M146V), APP(Swe), and tau(P301L) transgenes. Rather than crossing independent lines, we microinjected two transgenes into single-cell embryos from homozygous PS1(M146V) knockin mice, generating mice with the same genetic background. 3xTg-AD mice progressively develop plaques and tangles. Synaptic dysfunction, including LTP deficits, manifests in an age-related manner, but before plaque and tangle pathology. Deficits in long-term synaptic plasticity correlate with the accumulation of intraneuronal Abeta. These studies suggest a novel pathogenic role for intraneuronal Abeta with regards to synaptic plasticity. The recapitulation of salient features of AD in these mice clarifies the relationships between Abeta, synaptic dysfunction, and tangles and provides a valuable model for evaluating potential AD therapeutics as the impact on both lesions can be assessed.

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Diego. ADNI data are disseminated by the Laboratory for Neuro Imaging at the University of Southern California. We thank Drs. D. Stephen Snyder and Marilyn Miller from NIA who are ex-officio ADGC members. EADI. This work has been developed and supported by the LABEX (laboratory of excellence program investment for the future) DISTALZ grant (Development of Innovative Strategies for a Transdisciplinary approach to ALZheimer's disease) including funding from MEL (Metropole européenne de Lille), ERDF (European Regional Development Fund) and Conseil Régional Rotterdam, Netherlands Organization for the Health Research and Development (ZonMw), the Research Institute for Diseases in the Elderly (RIDE), the Ministry of Education, Culture and Science, the Ministry for Health, Welfare and Sports, the European Commission (DG XII), and the Municipality of Rotterdam. The authors are grateful to the study participants, the staff from the Rotterdam Study and the participating general practitioners and pharmacists. The generation and management of GWAS genotype data for the Rotterdam Study (RS-I, RS-II, RS-III) was executed by the Human Genotyping Facility of the Genetic Laboratory of the

The primal role that the amyloid-beta (Abeta) peptide has in the development of Alzheimer's disease is now almost universally accepted. It is also well recognized that Abeta exists in multiple assembly states, which have different physiological or pathophysiological effects. Although the classical view is that Abeta is deposited extracellularly, emerging evidence from transgenic mice and human patients indicates that this peptide can also accumulate intraneuronally, which may contribute to disease progression.

Progressive memory loss and cognitive dysfunction are the hallmark clinical features of Alzheimer's disease (AD). Identifying the molecular triggers for the onset of AD-related cognitive decline presently requires the use of suitable animal models, such as the 3xTg-AD mice, which develop both amyloid and tangle pathology. Here, we characterize the onset of learning and memory deficits in this model. We report that 2-month-old, prepathologic mice are cognitively unimpaired. The earliest cognitive impairment manifests at 4 months as a deficit in long-term retention and correlates with the accumulation of intraneuronal Abeta in the hippocampus and amygdala. Plaque or tangle pathology is not apparent at this age, suggesting that they contribute to cognitive dysfunction at later time points. Clearance of the intraneuronal Abeta pathology by immunotherapy rescues the early cognitive deficits on a hippocampal-dependent task. Reemergence of the Abeta pathology again leads to cognitive deficits. This study strongly implicates intraneuronal Abeta in the onset of cognitive dysfunction.