Volume 110, Issue s98

Alzheimer disease is the most common form of dementia in the aged population. Pathologically, Alzheimer disease is characterized by progressive synaptic and neuronal loss and the presence of diagnostic amyloid plaques, consisting of fibril b-amyloid peptide aggregates and neurofibrillary tangles containing hyperphosphorylated tau protein filaments. Although plaques and tangles were originally considered the mediators of neurotoxicity in Alzheimer disease, recent research has underscored the roles of soluble β-amyloid oligomers and tau molecules. Furthermore, new evidence has re-emphasized the important roles of endocytic, autophagic, and lysosomal pathways in Alzheimer disease pathogenesis—including the finding that deficiency or mutations in the gene that encodes presenilin 1 (the most common cause for early-onset familial Alzheimer disease) impairs the maturation of the lysosomal proton pump. The author discusses recent developments in the perspective of Alzheimer disease pathogenesis and potential therapeutic interventions.

The existence of an effective biomarker for early detection of Alzheimer disease would facilitate improved diagnosis and stimulate therapeutic trials. Multidisciplinary clinical diagnosis of Alzheimer disease is time consuming and expensive and relies on experts who are rarely available outside of specialty clinics. Thus, many patients do not receive proper diagnosis until the disease has progressed beyond stages in which treatments are maximally effective. In the clinical trial setting, rapid, cost-effective screening of patients for Alzheimer disease is of paramount importance for the development of new treatments. Neuroimaging of cortical amyloid burden and volumetric changes in the brain and assessment of protein concentrations (eg, β-amyloid 1-42, total tau, phosphorylated tau) in cerebrospinal fluid are diagnostic tools that are not widely available. Known genetic markers do not provide sufficient discriminatory power between different forms of dementia to be useful in isolation. Recent studies using panels of biomarkers for diagnosis of Alzheimer disease or mild cognitive impairment have been promising, though no such studies have been cross-validated in independent samples of subjects. The ideal biomarker enabling early detection of Alzheimer disease has not yet been identified.

There is neither proven effective prevention for Alzheimer disease nor a cure for patients with this disorder. Nevertheless, a spectrum of biopsychosocial therapeutic measures is available for slowing progression of the illness and enhancing quality of life for patients. These measures include a range of educational, psychological, social, and behavioral interventions that remain fundamental to effective care. Also available are a number of pharmacologic treatments, including prescription medications approved by the US Food and Drug Administration for Alzheimer disease, “off-label” uses of medications to manage target symptoms, and controversial complementary therapies. Physicians must make the earliest possible diagnosis to use these treatments most effectively. Physicians' goals should be to educate patients and their caregivers, to plan long-term care options, to maximally manage concurrent illnesses, to slow and ameliorate the most disabling symptoms, and to preserve effective functioning for as long as possible. The authors review the various current treatments for patients with Alzheimer disease.

Development of effective treatments for patients with Alzheimer disease has been challenging. Currently approved treatments include acetylcholinesterase inhibitors and the N-methyl-D-aspartate receptor antagonist memantine hydrochloride. To investigate treatments in development for patients with Alzheimer disease, the author conducted a review of the literature. New approaches for treatment or prevention focus on several general areas, including cholinergic receptor agonists, drugs to decrease β-amyloid and tau levels, antiinflammatory agents, drugs to increase nitric oxide and cyclic guanosine monophosphate levels, and substances to reduce cell death or promote cellular regeneration. The author focuses on medications currently in clinical trials. Cholinergic agents include orthostatic and allosteric muscarinic M1 agonists and nicotinic receptor agonists. Investigational agents that target β-amyloid include vaccines, antibodies, and inhibitors of β-amyloid production. Anti-inflammatory agents, including nonsteroidal anti-inflammatory drugs, the natural product curcumin, and the tumor necrosis factor α inhibitor etanercept, have also been studied. Some drugs currently approved for other uses may also show promise for treatment of patients with Alzheimer disease. Results of clinical trials with many of these investigational drugs have been disappointing, perhaps because of their use with patients in advanced stages of Alzheimer disease. Effective treatment may need to begin earlier—before neurodegeneration becomes severe enough for symptoms to appear.

More than 5 million people in the United States are afflicted with Alzheimer disease, a condition that is the seventh leading cause of death in the nation. Lacking definitive disease-modifying treatments, modern care for individuals with Alzheimer disease is necessarily multimodal, combining the use of approved pharmaceutic agents (ie, acetylcholinesterase inhibitors, N-methyl-D-aspartate receptor antagonists, antipsychotics), lifestyle and behavioral interventions, and components of palliative care. Some promising experimental treatments are undergoing clinical trials, including immunotherapy to prevent the deposition of β-amyloid, a protein implicated as an etiologic factor in the disease. The authors briefly examine the rationale and methods for screening patients for early indications of the onset of Alzheimer disease. They also describe current and potential treatments for patients with this disease.

Alzheimer disease is a devastating neurodegenerative disorder affecting millions of Americans. It reduces the ability of the individual to remain independent, places a burden on caregivers, and substantially increases healthcare costs. New treatments are being tested in numerous clinical trials with the goal of preventing or delaying the onset of Alzheimer disease, slowing or modifying the disease's course, or finding a cure for patients with the disease. Alzheimer disease research can successfully proceed only if individuals who have this illness are willing to participate in clinical trials. However, recruitment and retention of subjects in clinical trials for Alzheimer disease is a challenging task. Furthermore, because of reductions in decisionmaking capacities of individuals with Alzheimer disease, clinical trials also need to involve caregivers. The present article delineates unique hurdles encountered in the recruitment process for Alzheimer disease clinical trials. The article also identifies strategies for effective recruitment of subjects in Alzheimer disease clinical trials, including guidelines to help principal investigators and clinical research coordinators reach recruitment goals.