BLOOMINGTON, Ind. -- An interdisciplinary team led by Indiana University social neuroscientist Anne Krendl was awarded $3.5 million by the National Institutes of Health to navigate a phenomenon with major promise for the treatment of Alzheimer's disease: that the social connectedness of older adults predicts their vulnerability to Alzheimer's and general cognitive decline.
The team will focus more specifically on social cognitive abilities -- the skills we need to maintain social relationships -- and the part of the brain that supports them. These include the ability to remember faces and other information about people, the ability to understand the way other people think and feel, recognizing the differences between you and others, and adjusting for that.
By studying the dynamic between the brain, social cognition, social networks and cognitive ability, Krendl and her team ultimately seek to spark new ways of slowing down the progression of Alzheimer's.
The project builds on research by Krendl's co-principal investigator and frequent collaborator Brea Perry. A sociologist, Perry has shown that older adults whose social connections include a wide and varied circle of friends and acquaintances are less likely to experience cognitive decline than those with smaller, tightly knit networks.
Social networks typically get smaller as people age. Older adults more often keep close ties with family members, leaving behind a broader circle of friends and acquaintances. Yet this pattern of behavior, according to Perry, also leaves them more vulnerable to Alzheimer's disease.
"It seems from her work that having certain types of social networks can give you some sort of resilience to Alzheimer's and delay its onset," Krendl said. "What is it about these types of relationships that specifically helps to stave off the onset of Alzheimer's disease?"
The preliminary answer is that it has to do with having different types of relationships.
"Having to interact with different types of people in your network may challenge you to think in different ways," she said. "You know what to expect from the family members you see and talk to all the time, but this may be less clear for the friends or acquaintances you see less often. Your social cognitive abilities might be more challenged in these less frequent social interactions than they are in the more common ones."
Neuroscience also supports their insight into the links between social networks, social cognitive abilities and Alzheimer's. The parts of the brain where research is finding early markers of Alzheimer's is a set of interconnected regions known as the default mode network, Krendl said. That network "has also been widely tied to social cognition broadly."
"Social neuroscientists like to say it's 'the social brain,'" Krendl said. "It would make a lot of sense that if we know this part of the brain is at high risk for Alzheimer's disease, and we know it is involved in certain types of social functioning, that it might also play an important role in whether or not we can build resilience to Alzheimer's."
Connecting the dots
Krendl's team will investigate this dynamic with respect to Alzheimer's disease over the next five years in a series of three studies. The first and third parts of the study will bring 270 older adults to the Indiana Alzheimer's Disease Research Center at the IU School of Medicine on the IUPUI campus and a lab in the Department of Psychological and Brain Sciences at the IU Bloomington College of Arts and Sciences, to give them a battery of tests. These tests, given in the first, third and fifth year of the study, will measure general cognitive function, social cognitive function, and the size and composition of each individual's social networks and reflect change that occurs over time.
"The goal is to determine causality," Krendl said. "We want to know if social cognitive decline is causing general cognitive decline or the reverse, and if social networks are driving the changes we're seeing."
The second part of the study will use neuroimaging technology at the Indiana Alzheimer's Disease Research Center at IUPUI and the Imaging Research Facility on the IU Bloomington campus to look at the brain networks involved in social cognition. They will use these images to determine whether irregularities in the default mode network correspond to a diminishing social network and diminishing social cognitive skills.
The end result "will give us insight into how much of the cognitive decline related to Alzheimer's disease depends on social cognitive function, general cognitive function or both," Krendl said.
A window of opportunity
A telling feature of Alzheimer's disease is that the visible markers on the brain do not always match the symptoms. There is a gray area between when you develop the plaques and tangles characteristic of the disease and when you experience cognitive decline, a variable period of when onset begins.
Many researchers attribute the capacity to stretch that window to a function called "cognitive reserve." Krendl said the idea is that education and learning build new pathways in the brain or make the same pathways more flexible and resilient. When Alzheimer's disease blocks one or more of those pathways, cognitive reserve could, for example, give you the flexibility to circumvent the barriers or use different pathways to perform the same function.
Because there is at present no cure for Alzheimer's disease, Krendl asked, "Can we extend that window of opportunity? Even delaying a couple of years would have huge implications economically and for older adults' well-being. It would reduce the prevalence of the disease significantly."
In addition to Krendl and Perry, investigators include neuroscientists Andy Saykin and Liana Apostolova at the Indiana Alzheimer's Disease Research Center, and researchers Olaf Sporns, Kurt Hugenberg, Dan Kennedy and Hu Cheng from the Department of Psychological and Brain Sciences.
Additional sources of funding include the Indiana Clinical and Translational Sciences Institute's Networks, Complex Systems and Health Project Development team.