Dementia and clinical studies

Alzheimer’s disease causes 50-70% of all dementias and is a leading cause of mortality. The prevalence of Alzheimer’s disease is about one percent at age 65 and increases dramatically to between 20-50% in those older than 85 years. The pathological hallmarks of Alzheimer’s disease are extracellular accumulation of amloid β (Aβ) peptide in the brain (“senile plaque” SP) and by intraneuronal accumulation of hyper-phosphorylated tau protein in neurofibrillary tangles (NFT). This is accompanied by synaptic and neuronal losses. Neuropathological criteria of Alzheimer’s disease are based on density and distribution of SP and NFT in the brain. Thus, the pathological diagnosis is Alzheimer type pathology, while the diagnosis of dementia relies on clinical information. Lewy body disease are other common dementias, which present themselves clinically as Dementia with Lewy bodies or Parkinson disease dementia (PDD). There is commonly a large degree of overlapping Alzheimer’s disease and Lewy body pathology in demented individuals.