Alzheimer's disease (AD) typically develops slowly and gradually gets worse over the course of several years. It eventually affects most areas of the brain, including those important in memory, thinking, judgment, language, problem-solving, personality and movement. Many Alzheimer's patients typically live four to eight years after diagnosis. There are five stages
associated with AD: preclinical Alzheimer's disease, mild cognitive impairment, mild dementia due to Alzheimer's, moderate dementia due to Alzheimer's and severe dementia due to Alzheimer's. Dementia describes a group of symptoms affecting intellectual and social abilities severely enough to interfere with daily functioning. In the latest Diagnostic Guidelines for Alzheimer’s Disease of the National Institute on Aging/Alzheimer’s Association from 2011 the clinical phases are summarised as one stage thus the guidelines cover three distinct stages of AD.
People with mild cognitive impairment (MCI) have mild changes in their memory and thinking ability. These changes aren't significant enough to affect work or relationships yet. Thus the symptoms are not compromising a person’s independence. People with MCI may have memory lapses when it comes to information that is usually easily remembered, such as conversations, recent events or appointments. People with MCI may also have trouble judging the amount of time needed for a task, or they may have difficulty correctly judging the number or sequence of steps needed to complete a task. The ability to make sound decisions can become harder for people with MCI.
People with MCI may or may not progress to AD. In some cases, MCI is due to depression or a temporary medical complication. The diagnostic research focus is on standardizing biomarkers for amyloid and for other possible signs of injury to the brain. Currently, biomarkers include elevated levels of tau or decreased levels of beta-amyloid in the CSF, reduced glucose uptake in the brain as determined by PET, and atrophy of certain areas of the brain as seen with structural magnetic resonance imaging (MRI). These tests are at the moment used primarily in research settings, but may be applied in specialized clinical settings to supplement standard clinical tests to help determine possible causes of MCI symptoms.
Recent Clinicial Studies
Drugmakers have tried and failed for years to develop successful treatments for the disease. Two prominent recent cases are bapineuzumab and solanezumab, both administered intravenously. These antibody therapies seek to clear the brain of plaque caused by beta-amyloid, which accumulates in Alzheimer's patients. Bapineuzumab crosses the blood/brain barrier and seeks to clear brain cells of amyloid plaque. Solanezumab binds with a precursor of the plaque in the blood, with the aim of prompting the body to pull amyloid plaque from the brain. But last year Pfizer Inc. and Johnson & Johnson announced the end of the development of bapineuzumab, after two late-stage studies showed it worked no better than a placebo in patients with mild-to-moderate cases. Also, results from late-stage trials on solanezumab, developed by Eli Lilly failed to slow cognitive decline