Unlocking the secrets to Alzheimer’s disease through MRI
Alzheimer’s disease is the most common form of dementia and is a worldwide health concern. It is characterized by progressive and irreversible changes in memory, attention, self-care, behavior, motor skills, and language functioning. Currently, about 1 out of 9 adults aged 65 or older have Alzheimer’s, and this figure increases to 1 out of 3 for adults aged 85 or older. A total of 5.2 million Americans have a diagnosis of Alzheimer’s, and this number is projected to more than double by the year 2050 as life expectancy increases.
I am a doctoral candidate in the Clinical Psychology program at Wayne State University, conducting research with my primary mentor, Dr. John L. Woodard, and colleagues at the Cleveland Clinic, Marquette University, Rosalind Franklin University, and the University of Maryland. Our group studies Alzheimer’s disease; however, we do not directly work with anyone diagnosed with Alzheimer’s disease. Rather, we are working with healthy older adults without any major memory concerns. The reason for this is that the changes in the brain associated with Alzheimer’s disease accumulate for up to 20 years before we see any observable clinical symptoms such as memory loss or difficulty with self-care. Thus, by the time individuals are diagnosed with the condition, treatments may have little to no impact in altering the disease course because so much damage has already occurred.
Our lab is interested in attempting to detect signs of Alzheimer’s disease as early as possible. One promising method for studying risk for Alzheimer’s disease is functional magnetic resonance imaging (fMRI). fMRI is a special type of MRI scan in which we can detect which regions of the brain are most active when an individual is engaged in a particular task.
In our research, we have utilized a simple task called the Famous Name Discrimination Task, in which participants are shown a series of names on a computer screen while in the MRI scanner. The names are either well-recognizable names of famous people (e.g., Elton John, Bill Clinton) or non-famous names drawn randomly from the phone book. The participants’ task is simply to press a button indicating whether the name is famous or non-famous; most older adults can successfully complete this task at close to 100% accuracy.
We’ve found that when people recognize famous names, they use a network of brain regions that are also many of the same regions associated with the early changes in Alzheimer’s disease. Further, we can see differences in brain recruitment between healthy older adults with and without risk factors for Alzheimer’s, including having a parent with the condition and/or possessing the APOE ε4 allele, a gene associated with an increased risk for developing Alzheimer’s disease. For example, individuals with these risk factors typically display a greater amount of brain activity than those without the risk factors, indicating that these individuals may have to use more “brain power” to perform the task. This finding could indicate early changes in brain function potentially associated with Alzheimer’s disease. Importantly, we observed these differences in older adults who were performing normally on psychological tests of memory skills and who reported no concerns in self-care abilities.
When we followed these individuals 18 months later, we found that the fMRI brain activity was useful in predicting who showed early cognitive changes in memory testing. This finding substantiated that fMRI may be clinically useful in determining who is at the highest risk for developing Alzheimer’s disease. Identifying these individuals is important because it allows for preventative interventions to be implemented as early as possible. Specifically, a number of lifestyle behaviors, including physical activity, social engagement, cognitively stimulating activities, and a Mediterranean-style diet have all been associated with a lower likelihood of developing Alzheimer’s disease.
Currently, we are working on developing new tasks that may be even more sensitive to risk for Alzheimer’s disease. These tasks are similar in presentation style to the Famous Name Discrimination Task, but require recognition of more specific information associated with famous names, including an individual’s occupational category (e.g., Politician, Musician, Actor, etc.), specific bodies of work, and life events. We believe that studying this more specific information may be more sensitive to the subtle brain changes that occur early in the Alzheimer’s disease process.
For more information, please see:
Sugarman, MA, Woodard, JL, Nielson, KA, Seidenberg, M, Smith, JC, Durgerian, S, & Rao, SM (2012). Functional magnetic resonance imaging of semantic memory as a presymptomatic biomarker of Alzheimer’s disease risk. Biochimica et Biophysica Acta: Molecular Basis of Disease 1822, 442-456. DOI: 10.1016/j.bbadis.2011.09.016
Woodard, JL & Sugarman, MA (2012). Functional magnetic resonance imaging in aging and dementia: detection of age-related cognitive changes and prediction of cognitive decline. Current Topics in Behavioral Neurosciences 10, 113-136. DOI: 10.1007/7854_2011_159