involves, of all things, the same mechanisms stimulated when you stub your toe.
You undoubtedly know about inflammation. You stub your toe and local infectious agents—like bacteria—sweep in to take advantage, launching their Lilliputian attacks. Your body responds with swelling, redness, profanity. The classic inflammatory response is supervised by many molecules, including ones called cytokines. The response usually doesn’t last very long; the cytokines do their job and, in a few days, destroy the unwanted bad actors. This is a case of acute inflammation.
There is another type of inflammation, however, related to stubbed toes and also involving cytokines, but more relevant to our story. It is called systemic or persistent inflammation, the key difference tucked into its name: it lasts a long time. This type of inflammation occurs all over the body. It’s akin to getting tiny toe-stubs throughout the major organ systems, then having your whole body react with systemic, low-intensity inflammation as a result.
Don’t let the phrase “low intensity” fool you. Systemic inflammation damages many types of tissue over a long period of time, the way acid rain eats into a forest. It can even damage the brain, particularly white matter. White matter is composed of myelin sheaths that wrap around neurons, providing insulation to improve electrical performance. Without it, the brain doesn’t function very well.
How do you get systemic inflammation? The paths are many, including environmental factors such as smoking, exposure to pollution, or being overweight. Stress, ever the acid reflux of behavior, can incite it. And so can loneliness, according to Timothy Verstynen, director of the Cognitive Axon Lab at Carnegie Mellon University. He found in 2015 that chronic social isolation increases the level of systemic inflammation. Just how much damage loneliness causes in humans turns out to be astonishing. It’s at the same level as smoking. Or being too fat. The proposed molecular mechanism for this extraordinary observation is like a three-step feedback loop from geriatric hell: (1) loneliness causes systemic inflammation, (2) the inflammation damages white matter in the brain, and (3) the damage leads to the changes in behavior we mentioned, the ones resulting in fewer social interactions. Repeat.
If there is that thin a membrane between loneliness and brain damage, we have some serious thinking to do about how society treats its seniors. And how seniors treat themselves. We need to spend some quality time being grateful for the friends we have, and if the friendship tank is low, we need to seriously strategize about how to refill it.
A cultural shift
Refilling your friendship tank can be tough to do as you age. Researchers know you increase the quantity of friends you have in life until about age twenty-five. Then the number begins a long, slow decline, a deterioration that won’t stop until late into middle age. Baby boomers are notorious for losing friends in later life. As seniors, they have fewer social interactions with people of nearly every stripe—family members, friends, next-door neighbors—than seniors did in the previous generation.
Sociologists concur there are multiple reasons for this decrease, though not every researcher agrees on exactly what they are. Some point to the fact that people of child-bearing age move around a lot. This means communities are constantly being formed, uprooted, and re-formed—not a condition conducive to creating rich, long-lasting adult friendships. As a result, the guarantee of relational stability that comes from staying in one place gets torn up. My grandparents celebrated the multi-decade wedding anniversaries of friends with whom they had also shared a first-grade classroom. Such a thing is almost beyond imagining today.
It doesn’t help that people in developed countries are having fewer children than a generation ago. Over time, this means fewer uncles, aunts, and cousins. Even though that also means fewer annoying family reunions to attend, it shrinks the probability of sustaining long-term relationships with relatives (even if you did stay in one place). So you don’t have close friends. You don’t have much family. You barely even have a home. In terms of breeding toxic isolation, that’s like stagnant water to a mosquito.
On top of that, the nature of friendship is changing. The digital world provides enticing electronic substitutes for flesh-and-blood interactions. An intense research effort is under way to see if this matters, and I’ll have more to say about it in a later chapter.
The bottom line: environmental forces put seniors at greater risk for being alone than ever before. That’s noxious, for at a time when your brain is already under corrosive assault from Darwinian-approved natural causes, social isolation is the last thing it needs.
And that’s not even the full story. Nature plays just as strong a role as nurture. It is to these ideas that we next turn.
Face time
Prosopagnosia. It’s tough to pronounce, tougher to experience. People who suffer from the P-word aren’t able to do something even infants can do: recognize faces. They may have known you for years, but they won’t recognize you if you walk into the room five minutes from now. Nor will they recognize anybody else, even though they usually can recognize every thing else. No problem with hats, for example, or with eyebrows, or even with the concept of “face.”
Sufferers of prosopagnosia (logically called face blindness) usually resort to extraordinary measures to navigate their social world. A person might have to memorize the clothes their family members regularly wear in order to tell them apart. Others might have to pay close attention to the way people move or to specific postures, in order to recognize people at work. The late neurologist Oliver Sacks, a famous sufferer of face blindness, would have his guests wear name tags at parties so he could recognize them.
Not surprisingly, many people with the disorder withdraw socially, often suffering from social anxiety. This makes a certain amount of sense, for a great deal of social information is carried by the face. Clues to whether someone is happy or sad, contented or disgusted, potential mate or potential threat, show up in the eyes, cheeks, and jowls. Without the knowledge of what someone is feeling, sufferers withdraw into a Twilight Zone world where people can recognize you but you can’t return the favor. Sacks himself quit attending conferences and large parties.
Prosopagnosia is associated with lesions in a brain region called the fusiform gyrus, an area in the lower part of your brain not far from where your spinal column enters your skull. Strokes and various head traumas can damage the fusiform gyrus. Face blindness also is as heritable as eye color, which means you can get it from your parents. It is thought to affect about 2 percent of the population. But a less severe form of it seems to be related to normal aging as well.
As people get older, they suffer an increasing inability to recognize familiar faces, and they lose their perception of some of the emotional information those faces carry. We even know the reason. The neural tracts—the white-matter cabling—connecting the fusiform gyrus to other regions of the brain begin to lose structural integrity. Prosopagnosia illustrates an important principle in the brain sciences: specific regions of the brain exert a dictatorship over specific functions. When those regions become injured, those functions can be altered—or disappear.
The behavioral deficits are not global. Seniors can recognize emotions like surprise, happiness, and even disgust just fine (in fact, they score better on tests measuring disgust than younger adults do). Not so with sadness, fear, and anger. It’s an unfortunate twofer: seniors have a harder time recognizing people they know, sort of like a mini-prosopagnosia, and they have a harder time recognizing certain feelings those people are experiencing.
Do seniors withdraw socially as a result of these deficits, similarly to people with face blindness? Though there is (always) the need for further research, the answer may be yes. As we discussed, people begin to withdraw from social interactions as they age (remember the peak at twenty-five and downward slope at fifty-five?). Seniors show an especially
