The vagus nerve and depression

The vagus nerve is the longest in your body with fibers in nearly every organ, including your brain. There is one on each side of your body, each with up to 100,000 fibers. Most fibers send messages from your body to your brain, helping to maintain internal equilibrium. The information about the state of the body—such as heart rate—is carried to many of the brain regions implicated in psychiatric illness.

Investigators have long known that activating the vagus nerve with mild electrical pulses can treat epilepsy. A surgically implanted device, called a vagus nerve stimulator (VNS), cuts the frequency of seizures by 45 percent. In pursuing their research, scientists discovered an interesting side effect of the treatment: it made people happier.

A similar surgically implanted device is now being used to treat people with treatment-resistant depression. A 2017 study of 800 people with this condition found that five years of VNS fully cured 43.3 percent of them and halved the symptoms for 67.6 percent. (Depression is complex and variable. Different types of vagus nerve signals might be effective for different people.) VNS treatment strengthens connections between certain parts of the brain, including the parts associated with emotion processing. It also increases the activation of “feel good” hormones.

Now you can get devices that access the vagus nerve from outside the body. They’re called tVNS devices (the t stands for transcutaneous). You can buy these online! They come in two types, as you can see below. But studies show that surgically implanted devices are more effective.

In the interests of brevity, I’ve oversimplified this complex subject. For example, one of the research findings has shown a relationship between the vagus nerve and inflammation. I’ll discuss that topic next.

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What if you hit your head in a fall?

Friends who live in a retirement community tell us that, when residents fall, they are asked if they’ve hit their heads. If the answer is yes, they are taken to the hospital to be checked for possible brain injury. If the injury is severe, the person may have a life-threatening brain hemorrhage. But this is unlikely. If anything, the person might have a concussion. “Concussion” is another word for mild traumatic blunt injury.

My 97-year-old super-ager friend, Donna, who also lives in a retirement community, fell during a middle-of-the-night trip to the bathroom. As she was going down, she tried to fall like a 49er ("drop, roll, get up").  Nevertheless, she hit her head, but she did get up and went back to bed. The next morning she was dizzy and couldn't remember what had happened. After calling Resident Services, she was taken to the ER in an ambulance. She had a concussion.

Hitting your head can transmit a wave of pressure through the brain that can temporarily stun the neurons. Any damage to the brain caused by a concussion cannot be detected by a CAT scan or MRI. That’s because the damage occurs on a microscopic level. For this reason, a diagnosis is based on symptoms: headache, sensitivity to light, dizziness, nausea, vomiting, and amnesia. (With most concussions, there’s no loss of consciousness.) Such symptoms can last anywhere from seconds all the way up to weeks or even months. 

People who have had concussions may also experience memory problems, have trouble concentrating, suffer from drowsiness, and/or become irritable. For old people, concussion symptoms can be subtle and easily mistaken for normal aging.

Treatment for a concussion consists of rest, avoiding physical activities while recovering, and taking medicine for headaches. Donna says she "needed brain therapy." In fact, a series of therapists came to her apartment several times a week, helping her with movement and even speech. She felt "supremely supported and encouraged." She fell in early October. We met for lunch in late December. She says she's still concerned about loss of memory. To me, she seemed like her old self: alert, engaged, good humored, and energetic. She remembered how to get to the restaurant and directed me to it.

For an introduction to this blog, see I Just Say No; for a list of blog topics, click the Topics tab.

Have you fallen?

I got most of the following information from an article in JAMA (Journal of the American Medical Association). It was written by a retired physician, Dr. Bruce Campbell. At a visit to his doctor, he’s asked whether he has fallen in the past six months. He lies and says no. That’s what I do! Like him, I think it doesn’t count if you’ve done something like, in my case, tripping over a garden hose. (I have no trouble getting up.) I learned, in his article, why we’re always asked that question.

In the U.S., falls are reported every year by more than 14 million people over the age of 65 and are associated with about 90 percent of hip fractures. A history of one or more falls in the six months prior to a surgical procedure is associated with postoperative complications, higher levels of post-hospital care, and increased 30-day readmission rates.

The Centers for Medicare and Medicaid Services requires medical personnel to ask if you’ve fallen. It gathers this data to track the proportion of enrollees who have been assessed for their risk of falling.  This information, collected by doctors’ offices, is tied to reimbursement. The greater the proportion of patients queried, the better the reimbursement. (That’s what he wrote!)

As Dr. Campbell notes, admitting to a fall might trigger a cascade of medical tests, such a neuropsychiatric evaluation or stress test. Even his 90-year-old mother, who lived in a senior living apartment, lied about falling. When she fell and couldn’t get up, she called her son instead of the office. (She kept her phone in her pocket.) She was afraid she’d be hauled off to the hospital on a stretcher and subsequently moved to assisted living or a nursing home.

Dr. Campbell continues to lie. As will I.

Next week: What if you hit your head from a fall?

For an introduction to this blog, see I Just Say No; for a list of blog topics, click the Topics tab.

Doctors versus AI

Researchers conducted a small study to compare diagnoses performed by doctors versus those performed by AI, specifically ChatGPT. After recruiting 50 doctors for the experiment, the researchers divided the experiments into three groups: 1) Doctors not using the chatbot; 2) Doctors using the chatbot; 3) The chatbot by itself. The three groups were given six real-world case histories and told to suggest diagnoses and explain why they favored or ruled them out. The case histories had never been published, so neither the doctors nor ChatGPT would have foreknowledge about them.

Here are the results: Doctors who did not use the chatbot had an average score of 74 percent. Those who did use the chatbot had an average score of 76 percent. The chatbot by itself scored an average of 90 percent, vastly outperforming all the doctors!

[The researchers, in a subsequent interview, said "The results were not what we expected....we thought the doctors who had access to the chatbot were going to do way better than the doctors who only had access to the usual internet—UpToDate, PubMed, Google, whatever."]

The doctors using the chatbots often were not persuaded when the chatbot pointed out something that was at odds with their diagnoses. Instead, they tended to be wedded to their own ideas of the correct diagnoses. In describing how they came up with a diagnosis, doctors would say, “intuition,” or “based on my experience.”

Researchers also found that few doctors knew how to take advantage of the chatbot’s ability to solve complex diagnostic problems. For example, they treated the chatbot like a search engine, asking questions such as “What are the possible diagnoses for eye pain?” Only a few of the doctors figured out that they could copy and paste the entire case history into the chatbot and ask for a comprehensive diagnosis.

Hey! We could try this at home!

P.S. This post marks the tenth anniversary of my weekly blogs. 

For an introduction to this blog, see I Just Say No; for a list of blog topics, click the Topics tab.