INSTRUCTIONS |
1) For each field in your family tree enter the age of onset in the top field and the current age or age of death in the bottom. If the person did not have Alzheimer's disease (AD) symptoms, leave the field blank. It's OK to guess ages of onsets and deaths. |
2) Select the factors that apply to you from the drop down lists. Definitions of these factors are listed below. |
3) The graph returns your probabilities of being diagnosed with Alzheimer's disease at 5 year intervals. |
DEFINITIONS |
Ancestry: Enter your predominate family ancestry (race). |
History of Diabetes: Select if you have you been diagnosed with type 2 diabetes or hyperglycemia. |
History of Traumatic Brain Injury (TBI): A mild TBI is also known as a concussion. Altered level of consciousness is less than 6 hours. A severe TBI is one where the altered level of consciousness has lasted for more than 24 hours. A moderate TBI is one where you had an altered level of consciousness for between 6 and 24 hours. |
Education Level: Select your highest level of education. |
Exercise Level: Regular exercise is defined as 1.5 hrs/week of vigorous exercise (jogging, handball, etc), 2.5 hrs/week of moderate exercise (cycling, swimming, tennis, etc) or 4 hrs/week of light exercise (walking, bowling, golf, etc). Some Exercise is defined as half the previous amounts. |
Diet: Select if you adhere to a strict Mediterranean diet which consists of a diet high in fruits, vegetables, fish, nuts, legumes, & dairy with light alcohol consumption and minimizes the consumption of processed grains, refined sugars, alcohol, and red meat. |
WHY ARE YOU ASKING ME THIS? |
Family information: Family history (genetics) is the largest factor affecting the age and probability of onset of early onset AD. The gene predominantly involved is the apolipoprotein A4 (APOEe4) gene. Most people (87%) have no copies of the APOEe4 gene variant. These people have only a 20% risk of getting AD and have an average age of onset of 84 years old. 9% of the population has 1 copy of the gene doubling their probability of getting AD and having an average age of onset of 76 years old. People with 2 copies of the APOEe4 gene (4% of the population) have a 91% chance of getting AD with an average age of onset of 68 years.
Because we know the average age of onset and population with we can predict the probability of a subject the number of APOE genes. Because of a variety of other factors, the probabilities in this calculator do not add up to exactly 100% as they should. |
This calculator uses a Bayesian calculation to determine the probability of each genotype. A Bayesian calculation takes it's power from knowing the "prior" probability and takes this into account when determining the probability. For example, assume I didn't know anything about you. There is an 87% chance of you not having any copies of the APOEe4 genotype. However, lets assume that I know that all of your grandparents and grandparent got AD in their 60's. Your probability of having no copies of the APOEe4 gene is much lower whereas your probability of having 2 copies is now much higher. |
DID YOU KNOW
Sex: Women have a slightly lower rate of AD before the age of 65 than men, but a higher rate of AD at the age of 85.
Ancestry: Different races have slightly different incidence of AD. Blacks/Africans have the highest probabilities while Asians have the lowest.
History of Traumatic Brain Injury (TBI): Severe TBI (altered level of consciousness> 24 hrs) increases the probability of AD by 450% where moderate TBI (6-24 hrs) increases the probability of AD by 230%. Mild TBI (concussion) has no appreciable affect on AD.
Education Level: Low levels of education (no high school) is associated with an increased probability of AD of about 80%. High levels of education (ie university) likely result in reduced probabilities of AD but there is not a lot of evidence for this.
Exercise: Regular exercise reduces the probability of AD by approximately 40%. Some exercise reduces the probability of AD by approximately 30%.
Diet: A Mediterranean diet which consists of a diet high in fruits, vegetables, fish, nuts, legumes, & dairy with light alcohol consumption and minimizes the consumption of processed grains, refined sugars, alcohol, and red meat has been shown to reduce the risk of AD by 40%.
LIMITATIONS OF THIS CALCULATOR
1) AD is a complex disease and each individual is different. Therefore this calculator cannot provide a 100% accurate prediction of AD. Future clinical studies will determine how accurate this calculator is.
2) This calculator uses an additive approach to the factors listed above (TBI, exercise, etc). It cannot account for the complex interactions between these factors. Additionally, it is possibly to get an AD risk of greater than 100% for, let's say, someone with an extensive family history of AD, a history of severe TBI, poor diet, and only a primary school eduction. There is a good chance though that this person will have deceased prior to their probability exceeding 100%.