There's an old saying that the key to success is not what you know, but who you know.

When it comes to successfully maintaining your brain health as you age, you can take that expression one step further. It's not just who you know, but how you interact with them.

Joel Salinas, MD, an investigator at the Henry and Allison McCance Center for Brain Health in the Department of Neurology at Massachusetts General Hospital, is investigating the impact that social connections have on brain health as we age.

His research could inform the development of new strategies to help individuals stay cognitively healthy as they age—a crucial goal considering that the rates of Alzheimer's disease (AD) and dementia are expected to rise considerably over the next few decades, plus the recent high profile failure of new drugs for AD and dementia.

Tracking Social Networks in the Framingham Heart Study

In a study published in Alzheimer’s & Dementia: Translational Research & Clinical Interventions, Salinas and his research team investigated the connections between social networks and incidences of stroke and dementia in participants from the Framingham Heart Study (FHS), a long-term health study that is now enrolling its third generation of participants.

The original FHS study group was recruited in 1948 from every other household in the Massachusetts town of Framingham, thus many of the participants have strong relational and geographic ties to each other.

Salinas explains that these close connections allow researchers to identify social networks, primarily through the emergency contact information that participants provide and how those contacts change over time.

About a decade ago, researcher Nicholas Christakis, MD, PhD, MPH, (then at Harvard University, now at Yale) demonstrated that it was possible to track the impact of these social networks on health conditions such as obesity and smoking.

The Biological Connection

Using a similar approach, Salinas and his research team sought to compare information about the quality and quantity of participants' social interactions with levels of brain-derived neurotrophic factor (BDNF) in their bloodstream. BDNF helps to preserve existing neurons and support the growth of new neural connections.

"Lower BDNF levels and small social networks have separately been associated with a higher risk of stroke, cognitive dysfunction, and the accumulation of AD pathology," Salinas explains. "This study was the first to systematically examine the associations between social relationships and circulating BDNF in humans and how these associations might influence the risk for stroke and dementia."

The research team used several strategies to determine both the number of social connections that participants had and the quality of those interactions. Social connections were measured by the number of times participants socialized with friends and relatives, participated in religious meetings or services, and took part in group or community activities.

To assess the quality of social interactions, the team asked participants how often they had someone available to provide good advice, show love and affection, provide emotional support, or listen when they needed companionship.

"This is meaningful because of the wide degree of variation that can exist in the intensity, frequency, extent, and type of support provided through a social network," Salinas explains. "There are some social ties that may not be supportive at all."

Study Findings

Among 3,294 participants, controlling for age and sex, the team found that individuals who were more socially isolated (less social connections and lower quality social interactions) had lower circulating BDNF levels, while participants with greater emotional support had higher BDNF levels.

"To our knowledge, this is the first human study to associate higher serum BDNF levels with social support, let alone suggest an association with a specific type of social support—emotional support," Salinas says.

"Clinically, these findings highlight that developing and implementing strategies to provide greater emotional support and companionship to older adults may help reduce risks."

Increasing Social Support

The good news is that there are some simple and relatively low cost ways to increase social interactions and support among seniors.

For example, a study published in JAMA Neurology last March found that healthy individuals over the age of 70 who frequently performed certain activities—using a computer, participating in crafting and social activities, and playing games—had a significantly lower risk of developing cognitive impairment over the course of the four-year study.

"I suspect that the more social the activity, the more you benefit," Salinas says. "That's how neuroprogramming works. The more you use a neural pathway, the more reinforced it becomes, and the more likely it is to make additional physical connections with other brain cells and networks over the long term."

"It's like water running down the side of a hillside. The longer it runs, the more likely it will one day turn into an enduring river."

A Unique Research Perspective

Dr. Salinas has a complex neurological condition called mirror touch synesthesia, which causes individuals to vividly experience the same physical and emotional sensations they observe in other people, from the poke of a needle to the frustration of a patient coping with a neurological disorder. He has chronicled his experiences growing up with synesthesia and how it has influenced his career as a clinician and researcher in a book, Mirror Touch, that was released in 2017.

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