Postoperative cognitive dysfunction and Alzheimer disease

Abstract

IntroductionThere are many comorbid diseases that become more common with ageing (1). Alzheimer disease (AD), which was described by Alois Alzheimer in 1907, is the most common form of progressive, irreversible dementia in the elderly (1-3). It affects more than 25 million people worldwide; without a major therapeutic breakthrough, its prevalence is expected to increase more than 100 million by 2050 (1-5).Worldwide, 200 million patients undergo surgery under anesthesia each year. As overall life expectancy has increased, an increasing number of elderly patients are undergoing anesthesia. In addition, elderly surgical patients are more likely to have preexisting AD or be at risk for developing it. It is well known that POCD is an important problem for the elderly and patients with probable AD (6-11). On the other hand, there are no clinical studies that clearly demonstrate that general anesthesia (GA) causes cognitive dysfunction in patients with probable AD.This review article discusses the relationship between POCD and AD based on what we found in the currently published literature. Alzheimer disease or probable Alzheimer diseaseThe diagnosis of AD is based on a positive history, neurological examination, and neuropsychological tests. The National Institute of Neurological and Communicative Disorders and the Stroke-Alzheimer's Disease and Related Disorders Association Work Group criteria for diagnosing probable AD are documentation of dementia by clinical examination, deficits in two or more cognitive domains, absence of other systemic disorders, and progressive worsening of memory (12). Another commonly used criterion, according to the DSM IV (Diagnostic and Statistical Manual of Mental Disorders, 4th edition), is the loss of at least two of the following: orientation, memory, judgment, language, or calculation (13).AD patients usually present with a subtle onset of memory loss, followed by slowly progressive dementia over the course of several years. The course of AD is variable, and cognitive impairment, personality change, psychotic symptoms, incontinence, gait and motor disturbances, seizures, and myoclonus may occur. Memory impairment is progressive and destructive. AD also increases the mortality of the affected population. Life expectancy varies between 4 and 8 years after diagnosis (14)(15)(16)(17)(18)(19)(20)(21)(22).A definitive diagnosis of AD can be made only by autopsy of a patient's brain. This neuropathological evaluation reveals diffuse atrophy of the cerebral cortex, signifying loss of neurons. Diagnostic lesions are found on histopathological evaluation of most affected areas of the brain, which reveal the presence of large numbers of extracellular β-amyloid (βA) plaques and intracellular, neurofibrillary tangles (NFTs) (1-3,21-23). Even though plaques and NFTs are often found in cognitively normal Abstract: Alzheimer disease (AD) is the most prevalent neurodegenerative disorder in elderly people. Patients with AD appear to be particularly at risk for cognitive deterioration following anesthes...

Effects of recurrent sevoflurane anesthesia on cognitive functions with streptozotocin induced Alzheimer disease

“…It is thought that not only anesthetic agents, but also neurotoxicity, infl ammation, stress, intraoperative factors (e.g. hypotension, hypoglycemia) or the type of surgery have a role in the development of POCD (1,27). However, in recent researches there was an increasing concern that volatile anesthetics may impair cognitive functions over a long period of time, especially in older patients.…”

“…However, in recent researches there was an increasing concern that volatile anesthetics may impair cognitive functions over a long period of time, especially in older patients. Research showed that volatile anesthetics could increase amyloid peptide (Aβ) production and neurotoxicity, which are important pathological changes in AD development (1,11,12). Therefore, anesthesia and surgery are assumed as the risk factors that accelerate the onset of AD.…”

“…Worldwide, 200 million patients undergo anesthesia for surgical intervention each year. As overall life expectancy has increased, an increasing number of elderly patients receive anesthesia (1). Although the relevance of anesthesia and Alzheimer Disease (AD) fi ndings to old human has been questioned on theoretical grounds.…”

“…Alzheimer's disease (AD), which was described by Alois Alzheimer in 1907, is the most common form of progressive, irreversible dementia in the elderly. It affects more than 25 million people worldwide; without a major therapeutic breakthrough, its prevalence is expected to increase more than 100 million by 2050 (1). The diagnosis of AD is based on a positive history, neurological examination, and neuropsychological tests.…”

“…It has been shown that volatile anesthetics can induce synaptic dysfunction and neuronal apoptosis and thus lead to cognitive disorders in elderly brains. It is thought that intracellular β-amyloid levels increase the synthesis of β-amyloid and tau protein and disrupt the intracellular calcium metabolism (1). In many researches, isofl urane has been shown to increase caspase activity and increase amyloid β in vivo (11,12).…”