The first written records we have of depression are from Mesopotamia, in 2000 B.C. Those who were depressed were thought to be possessed by spirits, and thus treated by priests. The same was true of mental illness in other records in Babylonia, Egypt, and China, and often a type of exorcism was used as treatment, such as beatings, starvation, and restraint (1). The Greeks and Romans felt "melancholia" had spiritual and physical causes, and thus bathing, gymnastics, special diets, poppy extract, and donkey's milk were used as remedies. Hippocrates himself used bloodletting to help fix an excess of "black bile." Hippocrates described the symptoms of melancholia as persistent sleeplessness, lack of appetite, and depressed mood, along with occasional aggressive behavior, sometimes leading to suicide.
Cicero, a prominent statesman, argued that melancholia was "violent rage, fear, and grief," a similar explanation to Sigmund Freud's (anger turned inward) a few thousand years later. There was even a Persian doctor who recorded use of behavior therapy (rewards for positive actions). Then came the Middle Ages, and we were back to demonic possession again. Some doctors locked the mentally ill away in asylums, but many of the afflicted were thought to be contagious and were burned or drowned. Towards the end of the Renaissance, we were back to baths, humane treatment, and even music therapy.
The Age of Enlightenment brought the idea that mental illness was an inherited weakness of character, so we went back again to shunning and locking people away. However, scientists and doctors were experimenting more and more with different treatments, such as water immersion, a spinning chair, and Benjamin Franklin even came up with an early version of electroshock therapy (2). In the mid 1800s, we begin to get much more detailed descriptions of the symptoms of people admitted to asylums (3). Melancholia was still depressed mood, suicidal thoughts, worse in the morning, with prominent appetite loss and insomnia - very similar to the descriptions of the Greeks and Romans. In the late 1800s, as I remarked upon in my last post, the admissions to asylums skyrocketed. The author of (3) noted that syphilis was often blamed, however, only 14 cases were recorded in the asylum they studied, and that number did not explain the large increase in admissions overall.
Studies of human nutritional history show that rickets (a bone disease caused by severe vitamin D deficiency) became pandemic (especially in urban areas) in the 19th century (4). Here's a description of a common diet in working class England around the end of the 19th century: "The diets of working class women and children too often consisted largely of bread and tea, with sugar and the occasional smear of jam or margarine. Babies of all social classes were generally weaned on ‘pap’—bread and water or bread and milk." (4). Prior to this time, the vast majority of people lived on a farm, with (one would assume) access to fruits, vegetables, fresh meat, and the like. Weston Price found physical and mental deterioration in peoples as they abandoned their traditional diets and began to depend on sugar and refined flour. He also considered appropriate amounts of animal fat critical to good health (5).
I suspect that poor nutrition and deficient vitamin D may have led to quite a bit of mental illness in the 19th century (and today). Deficiency in B vitamins is also well known to cause psychiatric and neurological illness, and much of the cultural worry about physical and mental "racial degradation" disappeared after flour began to be enriched with B vitamins during WWII.
However, even in the early 20th century, the symptoms of depression were consistent with "melancholia." That is, intense sad mood, insomnia, agitation, suicidal thoughts, and appetite suppression. Then, and it is hard to say exactly when (maybe the 50s or 60s?), another type of depression began emerging, called "atypical depression." The symptoms include a milder depressed mood, poor energy, increased sleepiness, and increased appetite and weight gain (via carbohydrate craving). These symptoms are very similar to those of hypothyroidism (though usually thyroid tests are normal) and atypical depression responds to different classes of medication than old-fashioned melancholia. Chromium, a dietary supplement which is thought to suppress carbohydrate craving and speed metabolism, was found to be helpful for atypical depression in one trial. (6). Thyroid hormone (T3) is also used by psychiatrists for adjunctive treatment of depression. Atypical depression sufferers are also much more likely to have anxiety. While I've seen several textbooks quote the prevalence of atypical depression as 40% of depression subtypes overall, I would say in my clinic, the vast majority of my depressed patients have the atypical subtype. I only have two or three patients with classic melancholia. There is argument that atypical depression is actually a subtype of bipolar disorder, but I'm not convinced.
Atypical depression is generally considered milder than melancholia, and may not have shown up in the earlier asylum records for that reason. I've read quite a few novels over the years, and while I recall many literary descriptions of melancholia, I don't recall a whole lot of anxious characters with fluctuating depressed moods gorging on sugar. (That is obviously not a scientific sampling.) But in any event, the United States has done cohort studies every ten years, checking the incidence of mental illness in each successive generation. And in every generation, especially since 1950, depression has increased (increased diagnosis and awareness were, supposedly, statistically accounted for and do not explain the increase). Here's a link to the last cohort study. A woman today who has lived to old age has a 30-40% chance of having major depressive episode sometime in her lifetime. A man's risk is around 20-30% (7). As I stated in the first depression post, major depression and dysthymia (all subtypes included) afflict nearly 10% of us every single year.
Why is depression both changing and increasing? Well, Hibbeln and Salem * note that the dietary omega 6 to omega 3 ratio has also been increasing in the past century (yes, vegetable oils again!) And recall how atypical depression has similar symptoms to hypothyroidism? Whole Health Source has a terrific post linking linoleic acid (the predominant fatty acid in corn oil and other vegetable oils except olive and canola) to suppression of thyroid function at the liver. This would suggest that one could experience metabolic symptoms of hypothyroidism if one had a lot of linoleic acid in the tissues with normal serum thyroid hormone levels. I couldn't find an article noting T3 receptor suppression by linoleic acid in the brain - and this study seems to indicate that it doesn't happen in rat brains (8). Also, in my post on omega 3 fatty acid treatment for major depressive disorder, the depression with anxiety subtypes only trended towards doing better on omega 3s, whereas the treatment of plain depression showed significant positive effects. Since the modern, atypical depression is notable for its prominent anxiety, that may suggest the link to an overconsumption of omega 6 isn't the whole story behind the increase and alteration of depressive symptoms in the past decades.
There are other diet and depression theories also, related to that other "neolithic agent of disease" - sugar (or large amounts of processed carbohydrates in the form of starch.) Rob Faigin, a bodybuilder and lawyer looking for ways to build muscle without using steroids, wrote his book Natural Hormonal Enhancement in 2000. He postulates that a mechanism for modern depression is overall serotonin depletion caused by a diet high in processed carbohydrates (9). Each bolus of carbohydrate would cause a flush of serotonin (and thus good feelings and cravings for more while the carbohydrates are still working in your system), then a fall in serotonin and relative depletion once the sugar rush was over. Thus, in the short term, a switch from a high carbohydrate to low carbohydrate diet might cause depression, but in the long term, staying on a low carbohydrate might free one from mood swings and irritability (10).**
Any of you on low-carb diets? Do you feel depressed compared to how you were on a more traditional diet? While I am not extremely low-carb myself, on a primal style diet (lots of meat and fish, fruits, veggies, and rarely rice and potatoes for carbs, low in omega 6 and no wheat or refined sugars), I am personally more serene, more motivated, and more energetic. These rapid, painless, positive changes piqued my interest in the effects of diet on mood in the first place.
I suspect that depression, like other chronic disease states of Western Civilization, has a multifactorial dietary cause. Linoleic acid to increase the inflammatory soup, and some other factor (sugar rushes and crashes, perhaps?) to fuel the fire. I'll keep looking for more definitive information.
* Hibbeln's paper is extremely interesting, in that he brings up the contradiction between the findings that lower serum cholesterol levels are associated with increased depression and suicide, yet cardiovascular disease (and the higher cholesterol levels associated with that) is highly correlated with depressive disorders (p < 0.0000001!). It's also important to know that Hibbeln quotes a 1985 study by Eaton et al to suggest that saturated fat intake is higher today than it was in hunter-gatherers (9). According to Gary Taubes, Eaton repudiated his previous results in 2000, saying that he had not accounted for the hunter-gatherers eating organ meats and marrow, all high in fat and saturated fat.
**Judith Wurtman at MIT appears to be the major detractor of low carb diets due to possible depressive mood effects, but there is also this quote by her, which doesn't make any sense to me: ""When serotonin is made and becomes active in your brain, its effect on your appetite is to make you feel full before your stomach is stuffed and stretched." The researchers explain that people may still feel hungry after eating a large steak-their stomachs may be full but their brains may not be producing enough serotonin to shut off their appetites." In your experience, are you more likely to eat 5,000 calories worth of steak in one sitting, or 5,000 calories worth of potato chips or candy?? I think the fat/carb combo is far more likely to result in binging than steak. Or butter.