PHOTO: SHUTTERSTOCK

I remember a story a friend once told me about depression. She was trying to explain to her grandmother that she had been diagnosed with clinical depression, and her grandmother — well-intentioned, of course — wasn’t getting it.

“But what,” her grandmother kept asking, “are you sad about?”

It’s a flaw of language that we often use the same word for feeling depressed, a description of a state of sadness, and depression, a serious, common and deadly disease. While each subsequent generation advances its understanding of mental illness, the true nature of depression — that it is a serious disease unrelated to any temporary sadness, circumstances or flaw in character — is still misunderstood by many.

This lack of comprehension was thrown into the spotlight last week, when Sen. John Fetterman, the former Braddock mayor and freshman legislator, checked into Walter Reed Hospital to seek treatment for clinical depression. On television and social media, those who understood the gravity and nature of the disease expressed thoughtful wishes and apt messages of support.

Inevitably, though, representatives of a certain type of harebrained political opinion criticized or even mocked Fetterman, mistaking depression for some sort of weakness.

Even in an age of unabashed cruelty, that’s a depraved stance to take. I won’t name any pundits or accounts that went this route — but how they can walk through the day without crumpling under the weight of their own shame is beyond me.

For those unhappy few and anyone who may need clarification, let’s take the opportunity to discuss what depression is.

Depression is a disease that can disrupt nearly all aspects of one’s life. This disease causes a wide variety of symptoms, including an inability to sleep or focus on basic tasks, changes to appetite and energy level, difficulty focusing or thinking and negative thoughts. In some cases, depression can cause suicide. (It’s important to think of it that way — we like to think of this disease as leading someone to suicide, but it can very much be a true symptom, literally caused by depression.)

One in six adults in the United States will experience depression within their lifetimes, and that number is likely undercounted due to lapses in reporting. Additionally, depression can be caused by chemical changes in the brain naturally resulting from a variety of factors, from pregnancy — commonly known as postpartum depression — to major medical events, such as stroke and heart attacks. (While Fetterman has experienced depression at points throughout his life, this recent bout followed his 2022 stroke.)

Now, just as vitally, let’s talk about what depression is not.

Depression is not sadness, grief or malaise. Sadness is a natural part of life; grief is the result of a loss, such as the death of a loved one or a breakup. While life events and circumstances can cause depression, the sadness that results from such causes is not depression. Having been sad, even deeply so, at various points in life is not depression.

The novelist William Styron, who suffered from clinical depression, wrote of this distinction in his article-turned-memoir “Darkness Visible.” “The pain of severe depression is quite unimaginable to those who have not suffered it,” Styron said, “and it kills in many instances because its anguish can no longer be borne. The prevention of many suicides will continue to be hindered until there is a general awareness of the nature of this pain.

“Through the healing process of time — and through medical intervention or hospitalization in many cases — most people survive depression, which may be its only blessing; but to the tragic legion who are compelled to destroy themselves there should be no more reproof attached than to the victims of terminal cancer.”

Styron also wrote at length about the inappropriateness of the term depression for such a devastating disease, arguing that a misplaced word in our vocabulary might be a more apt description. “‘Brainstorm,’ for instance, has unfortunately been preempted to describe, somewhat jocularly, intellectual inspiration. But something along these lines is needed.

“Told that someone’s mood disorder had evolved into a storm — a veritable howling tempest in the brain, which is indeed what a clinical depression resembles like nothing else — even the uninformed layman might display sympathy rather than the standard reaction that “depression” evokes.”

Fortunately, depression is also not a lifelong affliction or a death sentence. Depression is routinely treatable through a combination of medication and psychological treatment. Unfortunately, old-school, stiff-upper-lip nonsense has stigmatized both treatment methods; there are still those who see medication as a sign that an individual can’t handle their own affairs and therapy as an unpleasant task. Such attitudes are retrograde, incorrect and somewhat silly; there should be no more apprehension about taking a pill to alleviate this disease as there would be about taking an anti-inflammatory to treat an allergic reaction.

This kind of thinking also represents a fundamental misunderstanding of who is running the show inside our heads. We like to think that we control our brains, coolly and rationally. Unfortunately, it is very much the other way around.

Inevitably, there are those who will not accept these realities; as Styron points out, those are people fortunate enough to have never dealt with depression themselves. To anyone who has — or has watched a loved one wrestle with the disease — it is well understood what depression is, and what it needs. Fortunately, Senator Fetterman was wise and well-informed enough to seek excellent treatment; because he did, I have no doubt that he’ll overcome this illness.

With better understanding — alongside that great missing ingredient, empathy — we can ensure that no one in our lives mistakes this disease for anything else.

If you or someone you know is struggling with depression or thoughts of suicide, please dial 988 for the Suicide & Crisis Lifeline.