Research into Alzheimer's disease, or AD, is crucial to develop accurate diagnostic tools, assess whether lifestyle changes or early interventions can alter its development, and develop effective treatments. There are many challenges to AD research, including, notably, a definitive diagnosis cannot be made until autopsy.
Alzheimer's Disease In Brief
AD is a neuro-degenerative brain disorder with no known cure. According to the Centers for Disease Control and Prevention, AD was the sixth leading cause of death in 2007.
The Alzheimer's Organization notes that AD's clinical symptoms include memory loss, language disorders and behavioral disturbances. Approximately half of dementia cases are due to AD.
Diagnosis and Definition of AD
One challenge in AD research is that a definitive diagnosis of AD is not possible until an autopsy of the brain tissue is performed. As a result, diagnosis is indirect, involving neuropsychological tests and ruling out other causes of dementia.
There is also a lack of scientific rigor in how the term AD is used. Some use AD to refer to "possible" Alzheimer's dementia and others use it to refer to "probable" Alzheimer's disease.
The combination of diagnostic and labeling imprecision results in scientists working with heterogeneous populations, which confounds research and undermines the statistical inferences that can be made.
Early Diagnosis
A key research challenge is improving early AD diagnosis to assess whether its course can be altered. Unfortunately, neuro-psychological assessments of those presenting with mild cognitive impairment may confirm impairment but they are unreliable in determining whether an individual will go on to develop AD. Although individuals may be classified as "possible" AD, there is great variability in status after two years. Some go on to develop AD, some develop other forms of dementia, others remain stable and others may improve.
In addition, many individuals who show signs of cognitive decline wait until symptoms are advanced before going to their physicians.
Lifestyle and Other Factors
Attempts to identify lifestyle or other factors associated with increasing or decreasing the risk of AD have examined social factors, mental and physical activity and other health conditions.
According to the Alzheimer's Association, this research involves large epidemiological studies such as the Nurses' Health Study. Epidemiological studies pose two problems. They are expensive, and they are retrospective and use statistical methods linking pre-existing behaviors to health outcomes. Although it is possible to "associate" these behaviors or conditions on a population level, this research fails to prove the connection.
Clinical Trials
According to the Alzheimer's Association, "Recruiting and retaining trial participants is now the greatest obstacle, other than funding, to developing the next generation of Alzheimer treatments."
Clinical trail recruitment is difficult for several reasons. First, recruitment of persons early in the illness is problematic and diagnosis tends to be in physicians' offices, rather than hospitals, so networks of recruitment centers and outreach are required. In addition, imprecise clinical diagnosis makes grouping participants difficult.
There are also ethical concerns about informed consent for clinical trials when individuals are cognitively impaired. In addition, few are willing to risk getting the placebo. Recruitment of minorities is particularly difficult.
References
- "International Journal for Alzheimer's Research": Diagnostic Tests for Alzheimer's Disease: Rationale, Methodology, and Challenges
- Alzheimer's Association: About Alzheimer's Association TrialMatch.
- Department of Health & Human Services: Testimony on Meeting the Challenges of Alzheimer's Disease
- The Commonwealth Fund: Alzheimer's Disease: Research Advances and Medical Reality: Erica Seiguer; July 2005.
- Centers for Disease Control and Prevention: Alzheimer's Disease
