from Part I - Quantitative methods in clinical neurology
Published online by Cambridge University Press: 29 September 2009
Analytic studies are used to define the relationship between a disease and its etiology or factors that may alter the course or manifestations of the disease. While these studies provide measures of the association between a risk factor, an exposure or a gene and a disease, Glynn points out that the association may also be due to chance, the result of an inherent bias or confounding. Analytic studies usually take the form of observational investigations, but can also include randomized clinical trials. All aspects of the disease pathway may be investigated in this fashion.
Disease pathway
The model of the classical disease pathway (Figure 1.1) offers a way of conceptualizing how and when factors act in the process of disease. Etiology refers to a specific cause, while pathogenesis defines the mechanism by which the etiology results in disease. The period between exposure to the cause and the initiation of the disease process is referred to as the induction period. This period of time is dependent on the etiology or cause; no specific time period can be defined. The period between the induction of disease and its detection has been termed by Rothman as the latency period.
In many neurologic disorders both the latency and induction periods may be lengthy. Associations between factors and disease may indicate where influences act in the disease pathway. For example, risk factors that act during the induction period will, most likely, have direct effects on risk. Traumatic head injury is an example of a risk factor that is considered by some to increase the risk of Alzheimer's disease by promoting the extracellular release of β-amyloid in the brain.
To save this book to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.