Theory and Practice of Neurogenesis

Even though I’m finding my self-care regimen for seasonal depression pretty adequate these days, I’m always interested in more tools. One thing that caught my attention recently was an interview with Brant Cortright in which he talked about his book The Neurogenesis Diet and Lifestyle.

Cortright has a bunch of interesting things to say, one of which I already knew: that depression is not a disorder of serotonin deficiency. According to him—and this I did not know—the way SSRIs work is by promoting neurogenesis. In the interview he said that depression turns out to be caused by a lack of neurogenesis, as are several other disorders (e.g. Alzheimer’s).

I checked the local libraries for copies of his book without success, but in my searches I happened upon this article: Successful brain aging: plasticity, environmental enrichment, and lifestyle by Francisco Mora, which seems to cover pretty much the same ground.

People are looking very hard at drugs besides SSRIs to promote brain plasticity, but the whole idea sounds problematic to me, so I’m interested in the various non-drug interventions suggested by Cortright and Mora. Fortunately, it seems that neurogenesis is easy to increase, by doing the obvious things we already know about:

  • Environmental enrichment
  • Calorie restriction
  • Aerobic exercise
  • Adequate levels of certain nutrients (omega-3s, vitamin E).

I think of my artist dates in particular as environmental enrichment, but of course time spent in nature counts as well. The parkour I do probably counts double, because there’s learning how to execute the moves, but there’s also learning to see the environment as a place where those moves are useful.

My weight loss practices have been substantially motivated by the science around calorie restriction as a way to improve health generally, with additional neurogenesis just one factor.

My experience over the previous 30 years convinced me that approaching calorie restriction in a numerical, analytical fashion—tracking what I ate, estimating the calorie content, aiming for some target X% below maintenance—would be unsuccessful. Instead, I came at it from the other direction: If I’m losing weight, I must be restricting my calories.

The caloric deficit implied by my weight loss over the past five years is just about 100 calories per day. Maintenance for me is probably around 1800 calories per day, so I’ve averaged about 5.5% below. It would probably be more accurate to say that I’ve averaged about 10% below maintenance for about half that time, as I’ve generally lost weight during the summers while maintaining a stable weight through the winters. Either number is well shy of the “20% to 40%” reduction that’s been shown to decrease the rate of aging of the brain, but I rather suspect that the benefit exists even at these lower levels—with the added bonus of being sustainable over a much longer period of time. (I mean, how long can you maintain a 40% deficit below maintenance before you simply waste away?)

According to Mora, aerobic exercise seems to increase neurogenesis by the same chemical pathways as calorie restriction. According to Cortright, it has to be aerobic activity of substantial duration—some twenty minutes or more. In particular, the sort of HIIT workouts so beloved of the paleo/primal folks don’t seem to produce the same effect. That’s fine with me: Humans are much too well-adapted for endurance running for me to buy into the idea that primitive humans didn’t do marathon-distance runs when they needed to. Besides, I enjoy long runs.

Of course, neurogenesis is reduced by the obvious things:

  • Neurotoxins (mercury, lead, pesticides, etc.)
  • Traumatic brain injuries (concussions, etc.)
  • High blood glucose levels
  • Stress.

My parents made a considerable effort to keep me and my brother free of neurotoxins, and I have managed to avoid concussions so far. I’m sure I subjected myself to excessive blood glucose levels for years, but I think I’ve got that under control now. I also subjected myself to excessive levels of stress for years, due to the vicious circle of my seasonal depression making me unproductive, my lack of productivity making me stress about losing my job, and the stress no doubt worsening my depression. I’ve got that under control now as well.

Really then, this whole neurogenesis thing doesn’t so much give me new strategies for staving off depression, as provide a conceptual framework for organizing the strategies I’m already using.

Even just that seems worthwhile.

(The image at the top is of these great doors at the Environmental Education Center at Kennekuk County Park. The branching trees reminded me of neurons, a little.)

Dealing with the dark

I’m prone to a particular bit of black humor this time of year. Usually a little earlier—maybe at the beginning of November—I’ll mention how early the sunsets are, how late the sunrises are, and point out that things are just going to get worse for six more weeks, and that it’ll be twelve weeks before things are this good again.

I joked similarly to my brother a day or two ago, and he pointed out that, although my joke is true in October or November, in December it’s wrong: by this point in the year things almost don’t get any worse. And he’s right. After all, the word solstice comes from the Latin for standstill.

Today there’s going to be nine and a half hours of daylight, and on the solstice there’s going to be nine and a third hours of daylight. Big whoop. I can deal with that.

Rounded to the nearest minute, we have already reached our earliest sunset of the year. That is, today the sun will set at 4:27. It will continue to set at 4:27 until December 13th, when it will set at 4:28.

(The sunrises continue to get later for a bit. It’s not until December 29th that we get a sunrise at 7:15, and not until January 4th that we get a sunrise at 7:14.)

I didn’t use to take much comfort in this. Knowing that things didn’t get much worse from here on out didn’t help when I was already depressed. But these days I tolerate the dark pretty well, and that means that I can take comfort from knowing that things are already about as bad as they’re going to get. Yes, it will still be mostly indoor exercise weather until March, but that’s okay—I have strategies for indoor exercise.

I’m not sure exactly what to credit for the improvement. I suspect that not working a regular job is the biggest factor, but taking vitamin D supplements seems to have helped as well. And, of course, getting enough exercise is both a cause and an effect.

 

Less SAD

Sunset SilhouetteThis used to be a pretty bad time of year. Already the days have gotten dark. Already dawn comes too late to get me up on time to go work at a regular job. Worse, the solstice is still six weeks away. That means it’s going to be twelve more weeks before things are even this good again.

It used to be that I’d start obsessing about the coming dark days only a few weeks after the summer solstice. July was usually fine, but sometime in August I’d start thinking that summer was winding down. I’d dread the prospect of getting up in the dark—something my brain chemistry thinks is profoundly unnatural. Shortly after that I’d be not merely getting up in the dark, I’d be heading off to work in the dark—and then coming home in the dark as well, since the sun would set before 5:00 PM until late January.

By now, despite a brief respite with the end of daylight savings time, I’d no longer be merely dreading seasonal depression, I’d be actually suffering from it.

The last three years have been much better. Not only am I suffering less during the depths of winter, I’m also much better off through late summer and early fall, because I’m not spending that time dreading the winter.

A lot of it, I think, comes from not having to work a regular job. Not only can I sleep until dawn (which is when I tend to get up even during the summer weeks when it means getting up before 4:30), I have more flexibility to take advantage of what hours of sunlight there are. Perhaps equally important, my depressive thoughts used to center on work: Because I was depressed, I’d have trouble getting things done. Because I was not getting things done, I’d worry about keeping my job. And then, in a classic spiral, worry over keeping my job would make me more depressed.

So, not having to work a regular job is win on both fronts, and is the main thing I credit with my improvement these past three years.

I did do one other thing that may have helped: I started taking vitamin D. I take 1000 IU daily from October to March, figuring that I get enough sunlight to make my own during the other months of the year. (It doesn’t take much.)

(I also now understand people who use tanning booths, many of whom have told me that they don’t do it because they want to have a tan, but because they “feel better” when do. I have no doubt that many are treating themselves for a vitamin D deficiency.)

Back when this was more of a problem, I experimented some with full-spectrum lighting, which some people find helpful. It never seemed to help me. One thing that I never tried—because the apparatus tended to be expensive—was a dawn simulator. I might have been really helped by a timed light that started out dim and then brightened over the course of thirty minutes to something akin to early morning sun streaming through the window.

I should say that my seasonal depression was never severe. I never felt I needed to seek medical treatment, for example. I handled it informally with the ordinary, obvious stuff—trying to get enough exercise, trying to get enough sleep, trying to minimize stress, adding some more fun stuff to my day when I was feeling out of sorts.

That was enough to keep things under control during the dark days of winter. But it wasn’t enough to keep me from spending late summer and early fall worrying about the dark days of winter.