Can Living Like Cavemen Reduce Depression?

Human bodies have not evolved fast enough to adapt to the demands of modern life. So believes psychologist Stephen Ilardi, PhD, author of The Depression Cure and associate professor of clinical psychology at the University of Kansas. Although we’re living longer and theoretically have better health care, the risk for serious depression has been increasing for more than a century. The disorder now afflicts one-quarter of Americans (a trend mirrored across most of the developed world), and has more than doubled over the past decade alone.

Dr. Ilardi told me that he has long puzzled over the epidemic of depressive illness, which continues to worsen despite the widespread use of antidepressant medications. In fact, the risk for depression is high throughout the industrialized and modernized world, but low among traditional and aboriginal cultures. Interestingly, modern-day aboriginal peoples enjoy dramatically lower rates of many forms of illness that commonly afflict Westerners — heart disease, diabetes, asthma, obesity and allergies among them. Dr. Ilardi believes that we should add depression to the list of “diseases of modernity.”

Our Hunter-Gatherer Ancestors

Until about 10,000 years ago, all humans were hunter-gatherers, living a lifestyle we know much about from the study of contemporary foraging groups. Dr. Ilardi’s “aha” moment came while reading the work of anthropologist Edward Schieffelin, PhD, who studied the Kaluli, an aboriginal group living in the highlands of Papua New Guinea. Although the Kaluli have a low life expectancy, high infant mortality and considerable intergroup violence, Dr. Schieffelin found that they suffer virtually no clinical depression. As Dr. Ilardi struggled to make sense of this surprising finding, he stumbled upon an important insight: the hunter-gatherer lifestyle features several elements — ranging from abundant physical activity to sunlight exposure to omega-3 consumption — that modern science has shown to be powerfully effective in fighting depression.

Maybe, thought Dr. Ilardi, the human species never evolved “antidepressive genes” because our bodies and brains simply weren’t designed for modern life — and our brains were protected for hundreds of thousands of years by the numerous antidepressant elements of hunter-gatherer life. As an example, Dr. Ilardi cites the fact that many of the compounds we need for survival aren’t made by our bodies — we haven’t evolved the ability to manufacture them, he says, because we’ve always been able to get them directly from our diets. Similarly, he theorizes that the human brain has no ability to stave off depression because until 10,000 years ago — the blink of an eye in evolutionary terms — all people lived an “antidepressant lifestyle.” Dr. Ilardi has spent the last four years developing and researching a treatment program for depression, Therapeutic Lifestyle Change (TLC), involving six curative lifestyle elements from the past that he asks his patients to weave back into the fabric of modern life. The program is described in depth in his recently published book, The Depression Cure.

The Six Elements of an Antidepression Lifestyle

1. Consume abundant omega-3 fatty acids. Hunter-gatherers ate a much more balanced diet than we do today, one rich in omega-3 and omega-6 fatty acids in a ratio of about 1:1. Over the past century, omega-6 fats began to dominate human fat consumption (due to the use of processed seed oil and eating meat that was grain-fed), to the point where the ratio of omega-6s to omega-3s is now about 17:1. Dr. Ilardi’s advice: Since omega-3 fats have proven antidepressant properties, take a daily fish-oil supplement that provides at least 1,000 mg of EPA (the version of omega-3 with the strongest research support in fighting depression).

2. Avoid ruminating on negative thoughts. Hunter-gatherers lived in the moment — survival depended on it. A well-researched and effective strategy for fighting depression encourages people to learn to interrupt rumination and focus instead on staying in the moment. Advice: Be continually engaged in what you are doing and monitor yourself to keep from brooding. Increase social interaction and shared activities. When you spend time alone, do things that keep your mind busy, like reading, watching television, painting, playing a musical instrument or cooking. Replace ruminative thoughts with positive ones. Write your thoughts down, and give yourself permission to walk away from them.

3. Get regular sunlight to keep your body clock in sync. Our ancestors spent much more time outdoors in the sunlight than we do. Sunlight not only resets the body clock each day — necessary for healthy sleep and hormone regulation — but it also enables us to manufacture vitamin D, which regulates 500 different genes expressed in the brain. Some researchers now say that most Americans are deficient in vitamin D, which is strongly anti-inflammatory… and, according to Dr. Ilardi, “a depressed brain is an inflamed brain.” Advice: 10 to 15 minutes of sunlight exposure daily between 11 am and 3 pm, depending on your skin pigment and the time of year, plus take 1,000 IU (international units) to 2,000 IU of Vitamin D in winter.

4. Stimulate key brain chemicals through physical exercise. Hunter-gatherers probably were physically active for three to four hours each day. That may be unrealistic today, but Dr. Ilardi says that it doesn’t take that much exercise to fight depression. Research at Duke University found, for instance, that 30 minutes of brisk walking three times per week was as effective at alleviating depression symptoms as the antidepressant Zoloft after four months, and considerably more effective at a follow-up six months later. By increasing dopamine and serotonin activity, exercise actually changes the brain chemistry, says Dr. Ilardi. Advice: 40 minutes of aerobic exercise three times per week, including 10 minutes to ramp up and 30 minutes of aerobic (just able to converse) activity.

5. Emphasize social connection in order to avoid the harmful effects of isolation. Hunter-gatherers didn’t spend much time alone. The typical ancient group had between 30 to 150 members, and most worked, cooked and slept together. Nowadays we are alone a lot — in our cars, at home, etc. Advice: Experience in-person community as much as possible.

6. Increase healthier sleep for brain and body recovery. Our ancestors got about nine to 10 hours of sleep each night, but many Americans are somewhat sleep-deprived, with 30% getting under six hours according to CDC figures. One recent study from the Stanford University Sleep Lab reported that most adults feel best after eight or nine hours of sleep. Advice: Make eight hours of sleep your goal. The Depression Cure lists 10 ways to improve your sleep habits.

Dr. Ilardi is conducting random-control trial research with a group of people he describes as severely depressed and difficult to treat. To date, about one-quarter of those on a wait list and receiving traditional therapy or medication have responded favorably over a 14-week period. In Dr. Ilardi’s Therapeutic Lifestyle Change group, approximately three-quarters of the group have gotten better.