Sunday, December 15, 2019
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Five million Americans and nearly 47 million people worldwide are estimated to suffer from Alzheimer disease (AD) or a related form of dementia.[1,2] AD is the sixth leading cause of death in the United States and the only top 10 cause of mortality that cannot be prevented, cured, or slowed. Still, researchers are gradually untangling the pathologic mechanisms behind dementia, advancing the understanding and care of the disease. The findings from a recent Medscape survey reflect clinician attitudes regarding the current state of AD diagnosis and management.
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The Medscape Alzheimer Disease Diagnosis and Treatment Survey was completed by 403 US physicians between October 9 and October 29, 2015. The sample comprised 150 primary care physicians (PCPs), 100 neurologists, 103 psychiatrists, and 50 geriatricians. All respondents were required to be practicing full-time and actively diagnosing and/or treating patients with AD. The majority of respondents—70% of whom were male—work out of office-based single- or multispecialty group practices.
Patients often perceive neurologists as the specialists who care for AD patients, but among survey respondents, geriatricians are most likely to report high volumes (50+/month) of AD patients, while psychiatrists report nearly as many AD patient encounters as neurologists. PCPs are least likely to report high volumes, probably because of their focus on general medicine.
Physician opinions are mixed as to how effective AD prevention strategies are. PCPs and geriatricians are more likely than neurologists and psychiatrists to believe that prevention is possible. Psychiatrists and geriatricians are significantly more likely than the other surveyed physician groups to believe that it is possible to slow the progression of AD.
Undiagnosed patients wanting to reduce their risk of developing AD most commonly ask about exercise and mental stimulation. Blood sugar control, stress management, and weight loss, though all potentially beneficial to reducing AD risk, are not frequently brought up by patients. Similar findings were reported by all specialty groups surveyed. This is perhaps not surprising, as the general population tends to perceive mental stimulation as the main preventive factor in AD. However, research indicates several potentially modifiable risk factors: diabetes, obesity, lack of physical exercise, untreated depression, low education, smoking, and hypertension.[3]
While physicians recommend numerous interventions in their patients at risk for or already diagnosed with AD, exercise, smoking cessation, and mental stimulation are most commonly recommended. This suggests that many undiagnosed patients are at least somewhat well informed of AD risk factors. Similar findings were reported by all specialty groups surveyed.
Structural MRI is by far the most favored neuroimaging study for working up a suspected case of AD, and even more so among neurologists. A sizeable proportion of physicians in other specialties (between one fourth and one third) do not order neuroimaging studies when assessing a patient with possible AD. The American Academy of Neurology recommends routine structural imaging (CT or MRI) in all cases of suspected dementia in order to rule out space-occupying lesions (eg, tumor, stroke, hydrocephalus). MRI is more expensive but provides better spatial resolution; CT is less expensive and exposes patients to minimal radiation. CMS has approved Medicare reimbursement for FDG-PET (which measures regional glucose uptake in the brain) in cases where there is a question of AD vs frontotemporal dementia. Although the FDA has approved several amyloid-PET scans, Medicare reimbursement is not available.
Physicians report relying on multiple neuropsychiatric scales for help in diagnosing and assessing the progression of AD, with the Mini Mental State Exam (MMSE) and the Montreal Cognitive Assessment (MoCA) being used most. Similar findings were reported by all specialty groups surveyed, though geriatricians were significantly more likely than other physician groups to favor the MoCA. The MoCA can be downloaded in multiple languages and does not require a licensing fee; the MMSE does require a fee.
Most physicians surveyed also believe that it's reasonable to discontinue pharmacotherapy with acetylcholinesterase inhibitors for patients with severe/late-stage AD. Geriatricians believe this significantly more so than other specialists and are in nearly universal agreement (98%) on this point. Clinical trials have demonstrated benefits for these drugs in nursing home patients and in those in the more severe disease stages. There is no specific test to determine when these drugs are no longer helpful, so it is left to the clinician/family to make that decision on the basis of a variety of factors (eg, quality of life). Geriatricians tend to see the patients with the most severe AD, for which the benefit of drugs is questionable.
The majority of physicians surveyed view the propagation of beta-amyloid/tau proteins as the factor contributing most to the onset of AD. Collectively, PCPs, neurologists, and psychiatrists are significantly more likely to also believe that inflammation plays a role in AD, compared with geriatricians (44% vs 36%, respectively), but are less likely to identify cardiovascular disease as a cause (26% vs 38%, respectively). The presence of plaques and tangles defines the disease, but whether they are a cause or effect has been debated. Efforts to clear amyloid plaques and tau tangles from the brain have not succeeded thus far. Inflammation is still a reasonable lead. Anti-inflammatory drugs seem to protect brain health when prescribed in normal aging and in people at risk for the disease; however, they appear to accelerate cognitive decline in those with more advanced disease. There is no test to determine the tipping point at which these drugs shift from helpful to harmful. Other interesting leads are also being pursued, such as insulin nasal spray therapy.
Reflecting the perceived importance of pathologic contributors to AD, anti-amyloid and anti-tau strategies are viewed as the most promising pursuits in developing effective AD therapies, with neurologists giving greater weight to anti-tau treatments vs other physicians. Anti-inflammatory and other strategies are perceived as secondarily important.
The Medscape survey suggests that although many physicians are not convinced that AD can be prevented, the majority of them—particularly psychiatrists and geriatricians—believe it's possible to slow the progression of the disease through modifying risk factors. While the underlying pathology behind AD and related forms of dementia is incompletely understood and existing drug therapies are limited in efficacy, various promising research avenues are being pursued that seek to improve the lives of patients—hopefully sooner rather than later.
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