By Briana Lee
One of the most unique cognitive abilities of humans is our ability to form memories and to learn. If a computer were to encounter something (i.e. sound), there must be a set of complex algorithms ready to analyze and categorize the sound, so it can be made into useful data. While there have been impressive strides in the fields of artificial intelligence and machine learning, these technologies are yet to match certain capabilities of our brains.
Our brains can form memories automatically, without any conscious effort, over a broad range of sensory modalities. When you walk into a familiar area, you immediately have a sense or feeling about if you’ve been there before. With Alzheimer’s disease, the changes in physiology and structure result in the loss of this particular function. Early on, a person may notice signs of mild cognitive impairment, such as difficulty navigating home even after living in the same house for 20 years.
Mild cognitive impairment is thought to be an intermediate phase prior to many forms of dementia, Alzheimer’s disease in particular. It could potentially provide a window of opportunity for lifestyle modifications or therapeutics to prevent disease progression; but as of now, there are no biomarkers for the early stages of Alzheimer’s disease ready for routine use in the clinic.
Because there is currently no early test to check for the disease, Alzheimer’s disease is largely diagnosed based on symptoms. However, there are many promising candidates for early biomarkers, one of which is functional magnetic resonance imaging (fMRI). Our study focused on how we can use imaging techniques to detect changes in brain activity in people developing Alzheimer’s disease. Now as a senior at the University of Washington, I am fortunate to pursue this work under the mentorship of Dr. Tara Madhyastha at the Integrated Brain Imaging Center.
In our brains, information is communicated through electrical signals between neurons. When we perform a particular mental task, certain groups of neurons become active in synchrony. We call this a “functional network.” There are specific functional networks for particular kinds of tasks. For example, in the brain, there are networks that are active when we pay attention to things or perform a task, such as take an exam or read a book. In contrast, there is also a network that engages when our minds are at rest (i.e. daydreaming). Because we cannot be intensely focused and daydreaming at the same time, the attention network and resting network have naturally opposing patterns of activity; when one gets stronger, the other gets weaker, and vice versa. From previous studies, we knew that the activity of the resting network was abnormal in Alzheimer’s disease. Building off this finding, we wanted to know how this activity came to be and changed over time.
For our study, we obtained neuroimaging data from the Alzheimer’s Disease Neuroimaging Initiative database. This massive dataset allowed us to analyze a large subject pool over a wide time span and examine three different groups: normal aging, mild cognitive impairment, and Alzheimer’s disease. We then compared the activity of the whole brain to the activity of the resting network. Specifically, in people with mild cognitive impairment, we identified changes in the activity of attention networks with the resting network. Normally, the attention networks and resting network work in opposition to each other, but in mild cognitive impairment, we found that the activity of the two networks increased together. In the future, we hope to pursue this finding in mild cognitive impairment to better understand the mechanism for this change and why. This distinction lays the groundwork for further characterization of this network activity and hopefully, allows us to develop into an early non-invasive biomarker for Alzheimer’s disease.
This was an exciting longitudinal study and I am looking forward to reporting our results at the Alzheimer’s Association International Conference (AAIC) this summer. AAIC is a fantastic conference where leading scientists in the field of Alzheimer’s disease research will attend and present their work. As my first conference, I’m thrilled to be given the opportunity to learn more about Alzheimer’s disease and recent discoveries in this field. Stay tuned for my next blog post, where I share some of this experience with you!