Despite being the leading cause of neurodegeneration and dementia in the aging brain, the cause of Alzheimer's disease (AD) remains unknown in most patients. The terminal pathological hallmarks of abnormal protein aggregation and neuronal cell death are well-known from the post-mortem brain tissue of Alzheimer's disease patients, but research into the earliest stages of disease development is hindered by limited model systems. In this thesis, an in vitro human neuronal system was derived from induced pluripotent stem (iPS) cell lines reprogrammed from dermal fibroblasts of AD patients and age-matched controls. This allows us to investigate the cellular mechanisms of AD neurodegeneration in the human neurons of sporadic AD (SAD) patients, whose development of the disease cannot be explained by our current understanding of AD. We show that neural progenitors and neurons derived from SAD patients show an unexpected expression profile of enhanced neuronal gene expression resulting in premature differentiation in the SAD neuronal cells. This difference is accompanied by the decreased binding of the repressor element 1-silencing transcription/neuron-restrictive silencer factor (REST/NRSF) transcriptional inhibitor of neuronal differentiation in the SAD neuronal cells. The SAD neuronal cells also have increased production of amyloid−β and higher levels of tau protein, the main components of the plaques and tangles in the AD brain
