THOMAS DEERINCK, NCMIR / Science Source
Given the patient's insidious cognitive decline, as well as increased agitation, irritability, anxiety, social isolation, inability to fully manage finances, loss of routine hygienic practices, and loss of interest in regular meals, this patient is diagnosed with probable Alzheimer's disease (AD) dementia and is referred to a specialist for further testing.
AD is one of the most common forms of dementia. More than 6 million people in the United States have clinical AD or mild cognitive impairment because of AD. By 2060, the incidence of AD is expected to grow to 15 million people. AD is classified into four stages: preclinical, mild, moderate, and severe. Patients with preclinical AD — a relatively new classification currently only used for research — do not yet show abnormal results on physical exam or mental status testing, but areas of the brain are undergoing pathologic changes. Mild AD signs and symptoms include memory loss, compromised judgment, trouble handling money and paying bills, mood and personality changes, and increased anxiety. People with moderate AD show increasing signs of memory loss and confusion, problems with recognizing family and friends, and difficulty with organizing thoughts and thinking logically, and they repeat themselves in conversation, among other symptoms. Severe AD is generally described as a complete loss of self, with the inability to recognize family and friends, inability to communicate effectively, and complete dependence on others for care.
Diagnosing AD currently relies on a clinical approach. A complete physical examination, with a detailed neurologic examination and a mental status examination, is used to evaluate disease stage and rule out comorbid conditions. Initial mental status testing should evaluate attention and concentration, recent and remote memory, language, praxis, executive function, and visuospatial function. Imaging studies may be performed to rule out other treatable causes of cognitive decline. In addition, volumetric studies of the hippocampus and 2-[18F]fluoro-2-deoxy-D-glucose PET with or without amyloid imaging can be used for early detection and differentiating dementia etiologies. Lumbar puncture as a diagnostic measure for levels of tau (which is often elevated in AD) and amyloid (which is often reduced in AD) is currently reserved for research settings.
Although the cause of AD is unknown, experts believe that environmental and genetic risk factors trigger a pathophysiologic cascade that, over decades, leads to Alzheimer's pathology and dementia. Universally accepted pathologic hallmarks of AD are beta-amyloid plaques and neurofibrillary tangles (NFTs). NFTs result from changes in the tau protein, a key chemical in neuronal support structures, and are associated with malfunctions in communication between neurons as well as cell death. Beta-amyloid plaques are dense, mostly insoluble deposits that develop around neurons in the hippocampus and other regions in the cerebral cortex used for decision-making, disrupting function and leading to brain atrophy. Risk factors for AD include advancing age, family history, APOE e4 genotype, insulin resistance, hypertension, depression, and traumatic brain injury.
After an AD diagnosis, physicians should encourage the involvement of family and friends who agree to become more involved in the patient's care as the disease progresses. These individuals need to understand the patient's wishes around care, especially for the future, when the patient is no longer able to make decisions. The patient may also consider establishing medical advance directives and durable power of attorney for medical and financial decision-making. Caregivers supporting the patient are encouraged to help balance the physical needs of the patient while maintaining respect for them as a competent adult to the extent allowed by the progression of their disease.
Currently, AD treatments are focused on symptomatic therapies that modulate neurotransmitters — either acetylcholine or glutamate. The standard medical treatment includes cholinesterase inhibitors and a partial N-methyl-D-aspartate antagonist. Two amyloid-directed antibodies (aducanumab, lecanemab) are currently available in the US for individuals with AD exhibiting mild cognitive impairment or mild dementia. A third agent currently in clinical trials (donanemab) has shown significantly slowed clinical progression after 1.5 years among clinical trial participants with early symptomatic AD and amyloid and tau pathology.
Jasvinder Chawla, MD, Professor of Neurology, Loyola University Medical Center, Maywood; Director, Clinical Neurophysiology Lab, Department of Neurology, Hines VA Hospital, Hines, IL.
Jasvinder Chawla, MD, has disclosed no relevant financial relationships.
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