ABSTRACT
Alzheimer's disease (AD) is a clinicopathologic entity characterized by clinical evidence of dementia and histopathologic evidence of neuritic plaques and neurofibrillary tangles in the brain. AD is the most common cause of dementia, accounting for over one-half of cases. Well-known environmental risk factors include age, cerebrovascular disease, stroke, diabetes, dyslipidemia, hypertension, smoking, obesity, and head trauma. The neurofibrillary tangles (NFTs) are intracellular, and made up of tau, a microtubule-associated protein involved in intracellular matrix assembly and stabilization. Under physiologic circumstances, tau is phosphorylated by kinases and dephosphorylated by phosphatases. Pseudodementia from depression should be considered in the differential diagnosis of AD. It should also be noted that depression and especially anxiety often accompany the early stages of AD. Brain imaging should be obtained. Magnetic resonance imaging scan is preferable, although computed tomography may be substituted. In the individual with cognitive impairment, genetic testing can be used to determine whether the disease is genetically transmissible.
