Alzheimer’s disease
Alzheimer’s disease (AD) is the most common cause of dementia in older adults. The cause of the disease still is unknown and there is no cure. While the disease is usually begins after the age 65, and risk of AD goes up with age, it is important to note that AD is not a normal part of aging. The aging of the baby boom population has made AD on of the fasting growing disease; estimates indicate that by the year 2040, some 14 million people in the United States will suffer from Alzheimer’s disease.
Cognitive deficits are the primary symptoms of AD. Early on, there is mild memory impairments; as the disease progresses, memory problems increase and difficulties with language are generally observed, including word-finding problems and decreased verbal fluency. Many patients also exhibit difficult with visuospatial tasks. Personality changes are common, and patients become disoriented as the memory problems worsen. A progressive deterioration of function follows and, at last stages, the patient is bedridden, nearly mute, unresponsive, and incontinent. A definitive diagnosis of AD is not possible until autopsy, but the constellation of symptoms and disease progression allows a reasonably certain diagnosis.
Gross pathology consistent with AD is mild to severe cortical atrophy (depending on age of onset and death). Microscopic pathology indicates two classic signs of the disease even at the earliest stages: the presence of senile plaques (SPs) and neurofibrillary tangles (NFTs). As the disease progresses, synaptic and neuronal loss or atrophy and an increase in SPs and NFTs occur.
While many neurotransmitter systems are implicated in AD, the most consistent pathology is the loss or atrophy of cholinergic neurons in the basal forebrain. Medications that ameliorate the cognitive symptoms of AD are cholinergic function enhancers. These observations emphasize the importance of cholinergic systems in cognitive function.
References:
- Medical physiology, Lippincott Williams & Wilkins 3rd edi.
- Harrison’s Principles of Internal Medicine, 17th edition.
- Davidson’s Principles and Practice of Medicine, 20th Edition
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