Meet the Author
Sam DuBois is a doctoral candidate in the Kinesiology department at the University of North Carolina at Greensboro. She has earned a master’s degree in Sport and Exercise Psychology and is currently working on her PhD. She has finished all coursework and is in the beginning stages of her dissertation. She plans to become a university faculty member to teach and pursue research.
Ms. DuBois’ faculty advisor is Dr. Jenny Etnier, Julia Taylor Morton Distinguished Professor, Kinesiology Department Chair, and Principal Investigator of the Physical Activity and Alzheimer’s Disease 2 (PAAD2) Study. The PAAD2 Study is a federally funded research project that explores the protective benefit of exercise for people with a family history of Alzheimer’s disease or dementia. Ms. DuBois has been a part of the PAAD2 research team as a graduate research assistant since 2019. She leads cognitive, exercise, and MRI assessments and is a level IV MRI operator. She also helps with processing data, scheduling assessments, and leading MRI training sessions for students.
DuBois and Dr. Etnier at the UNCG Graduate Research Showcase
Forming the Research Question
As an involved member of the PAAD2 research team, Ms. DuBois is hands-on with data collection (e.g., working with study participants, running the MRI equipment, etc.) and data analysis (e.g., inspecting data with statistical computer programs, interpreting results, etc.). She uses these experiences along with knowledge learned throughout her time as a graduate student to explore unanswered research questions. Recently, Ms. DuBois worked with Dr. Jenny Etnier, Dr. Shin Park, Dr. Chris Wahlheim, and Dr. Laurie Wideman as mentors and co-authors on her research titled, The Association Between Aerobic Fitness and Mnemonic Discrimination in Middle-Aged Adults at Genetic Risk for Alzheimer’s Disease. We were able to ask her some questions about this project to learn more.
Can you walk us through the title and what it means?
My research is exploring the question, does APOE ε4 carrier status influence the relationship between aerobic fitness and mnemonic discrimination? The data is from participants who are part of the ongoing PAAD2 study. They are all between the ages of 40 and 65 and have a family history of Alzheimer’s disease (AD) or dementia. Individuals who carry the Apolipoprotein E (APOE) ε4 allele are at a heightened genetic risk for AD. We used saliva samples to determine APOE ε4 carrier status (carriers or non-carriers). This information was used to examine if APOE ε4 carrier status and aerobic fitness predicted performance on a mnemonic discrimination task sensitive to hippocampal integrity.
Aerobic fitness was measured by walking on a treadmill with an assessment called a submaximal exercise test.
Mnemonic discrimination was measured by performance on a modified object recognition task.
How did you come up with this research question?
Existing research shows three key things related to forming this research question:
1. During the early stages of AD, the hippocampus experiences detrimental changes that impair its ability to form distinct memories (Rao et al., 2022). This is why memory problems for recent information are often the first noticeable symptom of the disease.
2. APOE ε4 carriers are at a heightened genetic risk for AD (Corder et al., 1993) and exhibit hippocampal changes even in the absence of AD symptoms (Lind et al., 2006).
3. There is a positive association between aerobic fitness and hippocampal integrity. Adults who have higher aerobic fitness also have greater hippocampal volume and better hippocampal function (Erickson et al., 2009).
However, it is unclear how a person’s genetic risk for AD influences this relationship between aerobic fitness and hippocampal integrity. Exploring this interaction could lead to preventative interventions aimed at preserving the integrity of the hippocampus and the memory abilities it supports for those at a heightened genetic risk of AD.
The term mnemonic discrimination is not used in everyday conversations, what is it?
Mnemonic [nuh-MON-ik] discrimination is the ability to differentiate a current event from similar past events. For example, to remember the location of your parked car, you must differentiate your current parking spot from all the parking spots you have previously occupied. Most days we can successfully do this, but other days we may stand in the parking lot frustrated and confused unable to remember the location of our parked car because of the interference created by existing memories for our previously occupied parking spots.
Our mnemonic discrimination ability is enabled by the hippocampus and its ability to form highly detailed, distinct memories (Yassa & Stark, 2011). Unfortunately, because mnemonic discrimination is dependent on the hippocampus, it is often one of the first memory abilities impaired by AD. Since APOE ε4 carriers are at a heightened genetic risk for AD and exhibit hippocampal changes even in the absence of AD symptoms, they are also at risk of experiencing declines in mnemonic discrimination.
In a research setting, we can examine a participant’s mnemonic discrimination with a specific type of memory test. The PAAD2 study uses the Mnemonic Similarity Task created by Dr. Stark and colleagues (Stark et al., 2019). During this task, participants first study images of everyday objects and decide if each object is an “indoor” or “outdoor” object. Then they complete a memory test during which they indicate if objects are the exact same as previously studied objects, similar but not identical to studied objects, or entirely new objects. The ability to differentiate “similar” objects from previously studied “old” objects reflects successful mnemonic discrimination and is sensitive to hippocampal integrity.
Findings and Conclusions
To examine the data, statistical computer programs are used. The information that is outputted is then interpreted into results. Ms. DuBois’ uses statistical devices such as graphs, p-values, and correlation coefficients when presenting results in poster and PowerPoint presentations. Then, the results provide meaningful information about the research question.
After looking at all this data, what were the findings?
After analyzing the data, I found that for the objects that are the most “similar” to previously studied objects and therefore the most difficult to discriminate between, there was a statistically significant interaction between APOE ε4 carrier status and aerobic fitness. This interaction indicates that higher aerobic fitness is associated with better mnemonic discrimination only for the APOE ε4 carriers. In contrast, for the APOE ε4 noncarriers no significant relationship was observed between aerobic fitness and mnemonic discrimination.
Since previous research has shown that APOE ε4 carriers are at a heightened genetic risk for AD and exhibit hippocampal changes even in the absence of AD symptoms, this finding suggests that having higher aerobic fitness may protect against some of these hippocampal changes that make these individuals more susceptible to experiencing impairments in mnemonic discrimination.
Why is this important?
These results suggest that aerobic fitness may benefit the hippocampal-dependent memory of those at a heightened genetic risk for AD. Developing physical activity programs aimed at improving aerobic fitness may therefore be a promising preventative intervention for this at-risk population.
Sharing the Findings
Ms. DuBois presented these findings at the UNCG Graduate Research and Creativity Showcase on April 4, 2023. This annual showcase presents the accomplishments of UNCG’s graduate students to the community. Graduate students explain and present their work through posters.
Left: DuBois with her poster at the showcase
Right: Graduate student posters displayed at the showcase
She also applied to present her work through a poster presentation at the North American Society for the Psychology of Sport and Physical Activity (NASPSPA) conference taking place this summer in Toronto. Not only was she accepted, but the reviewers asked Ms. DuBois to give a verbal presentation where she will speak to conference attendees about this research.