More threads by David Baxter PhD

David Baxter PhD

Late Founder
The 'Bless You!' Blues: A surprising relationship between depression and allergies
By Richard Firshein, Psychology Today Mar/Apr 1999

I treat many patients with allergies and am always surprised by how many complain about feeling depressed yet never make a connection between the two conditions. The fact is that individuals who are prone to allergies are more vulnerable to depression. And not just because their symptoms make them miserable.

There is a unique, undeniable link between allergies and depression. A study in the journal Psychotherapy and Psychosomatics monitored 379 students who were depressed and fatigued. They found that 71 percent of those who had ever been diagnosed with depression also had a history of allergies. The worse they rated their depression, the worse their allergies. A review article in the Psychological Bulletin also found a very high prevalence of allergies in people with depression. And individuals with the most common type of allergic reaction, known as Type 1 IgE, are far more likely to get depressed after a bout with the flu than people without allergies.

Sometimes, depression is the only allergic symptom a patient mentions. One young woman complained that she got depressed every September. Of course, this could stem from disappointment at the end of a summer vacation or anxiety at the coming school year. But the cause of her foul mood seemed quite specific and physical: she was allergic to ragweed. Allergy shots cleared up her blues.

Scientists don't understand the precise mechanism by which allergy might trigger depression, but we do know that a chemical called histamine is released from specialized cells during allergic reactions as part of the body's immune response. The brain also contains histamine receptors. So when our immune systems release histamines in response to pollen or mold, these histamines might also impact our mood by latching onto brain cells. The connection between the immune and nervous systems is an exciting area of research that is only beginning to be explored.

Of course, allergies aren't always linked to bad moods, and any time you're physically ill, you're likely to feel down. When I treat someone for allergies, I know that as their symptoms improve, their mood will improve, too. I advise patients to avoid allergens like dust and mold, to take allergy shots and to try natural remedies like quercetin, a flavonoid that blocks allergic reactions; nettles, an herb that regulates histamine release; and vitamin C, a known antihistamine.

Allergies are part of a mind-body pathway which we don't completely understand. Still, there does seem to be some special feedback loop between allergies and mood changes that will become clearer as scientists further explore the chemical connections between our brains and bodies.
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