When I was seven, my bedroom was a girlish wonderland of pink ruffled pillows and dainty floral-trim wallpaper. At night, as I tried to fall asleep, I could make out tokens of an idyllic childhood: shelves full of Baby-sitters Club books, an enviable collection of corkscrew-curled porcelain dolls, and photos of my smiling parents. Some nights, I would reach down and pet Disney, the family mutt. Although doing so was totally impractical, I occasionally kept him leashed to my bed. I was convinced that my house was about to burn down, and wanted to make sure he wasn’t left behind.

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Night after night, I saw the flames encroach upon my bed. I spun every thought to its worst-case scenario in a propulsive cycle of what-ifs. What if my parents died? Or my brother? If we did survive, where would we live? Would I have to change schools? Then, at around one or two in the morning, unable to handle the dread any longer, I would run to my parents’ room and wake my dad. With superhuman patience, he would walk me through the entire house, pointing out all the fire alarms and double-checking that the oven was off.

In the mornings, my dad, a real-estate lawyer, flew out the door at eight, leaving my mother, a GP with an office in North York, Ontario, to marshal the kids through their morning routine. I ate breakfast. I brushed my teeth. I tied my shoelaces. I climbed into our minivan for the drive to school. And at night, once again, I’d lie awake, wired and tense, staring at the shadows my night light cast on the ceiling. This was our normal. My crippling anxiety started when I was a toddler, I’m told, and only worsened over the next several years as I inched toward puberty.

On September 3, 1996—the first day of grade six—I suffered a mental breakdown. I’d never been a popular kid, but I had one close friend and that was enough. After a summer apart, I spotted her in the schoolyard, talking in a circle of girls. I ran up excitedly and said hi. She clipped a quick greeting, then turned her back and ignored me. I went off like a bomb. It began in my stomach: a wrenching, turbulent nausea that radiated out to my hands and feet, then crept up into my chest until I couldn’t breathe. I’d spent my entire childhood stewing in amorphous terror, awaiting some unknown calamity. Maybe this was it. I ran to the administration office in tears and said I was sick—and I was.

The illness manifested as an all-consuming fear of school. Over the next few weeks, as my parents tried to convince me to return, I cried and hyperventilated; failing that, I destroyed the furniture, throwing chairs and slamming doors until the hinges came loose. A few times, my parents managed to get me to class for an hour or two. I’d stare into my lap, chin quivering and shoulders convulsing, using every ounce of strength I had not to shatter in front of my schoolmates. Other times, I sat in a spare classroom hurling abuse at my mom—I told her I hated her, that she was a terrible mother, that I wished she’d die in a cave on the other side of the world. I also stopped eating and lost about twenty pounds. One day, I announced I’d rather be dead than go back to school. That whiff of suicidal thinking scared my parents so deeply that the next morning, we drove to the Hospital for Sick Children in downtown Toronto.

This was the era of peak Prozac. In its second year, a decade earlier, the pharmaceutical phenomenon racked up more than $100 million in global sales. It was hailed as a panacea: doctors prescribed it for obsessive-compulsive disorder and bulimia. Between 1981 and 2000, the number of antidepressant prescriptions in Canada increased by 353 percent, from 3.2 million to 14.5 million.

But the backlash was as ferocious as the boom. Many patients experienced what came to be known as “Prozac poop-out,” in which their serotonin-induced euphoria dissipated and their depression returned—an apt metaphor for the shift in the way selective serotonin reuptake inhibitors, or SSRIs, came to be perceived. Increasingly, doctors worried about the potential side effects of the drugs; a handful of reports pointed to agitation, violence, and even suicidal thoughts in users. Patients started complaining that in addition to alleviating their depression, the drugs also numbed their feelings—a condition known as the “anti-depressed personality.”

For children, medication was practically verboten. At SickKids, my parents and I met with a militant child psychologist who prescribed a course of discipline. My refusal to go to school was merely separation anxiety, he claimed—I was being stubborn and manipulative, and my parents shouldn’t give in. During each of several subsequent visits, he gave my parents a version of the same advice: roll me into a carpet and carry me into the classroom if necessary. My parents refused. Eventually it occurred to them that medication might be the only thing that could make me better.

My family doctor referred me to one child psychiatrist, who diagnosed me with a depressive illness, and then another, who pinpointed it as generalized anxiety disorder. He prescribed 250 milligrams of Zoloft, even though Health Canada hadn’t approved the drug or any other antidepressant for patients under eighteen. Almost twenty years later, tens of thousands of young Canadians are taking antidepressants. (A recent study from the University of Saskatchewan, for example, suggests that fifteen out of every thousand Saskatchewanians under the age of twenty have been prescribed antidepressants.) Yet the old fears persist. What do these medications do to the developing brain? More crucially, what impact do they have on emerging identity? As part of the first generation to grow up on antidepressants, I think I know.

When I was diagnosed with a mental illness at age eleven, my doctor—soft-spoken and straitlaced, with a thick moustache—explained that I was suffering from a chemical imbalance in my brain. At the time, the medical community believed that depressive disorders were primarily caused by a deficiency of monoamine neurotransmitters, which help regulate moods and general happiness. The new drugs were thought to stall reabsorption of serotonin into nerve cells and allow it to linger instead in the synapse between cells, where over time it may help transmit the “happy” message. It sounds logical, but even today scientists have unanswered questions. Since patients were seeing improvement, doctors figured, they must have been low in monoamines.

And I did improve. A week or so after I started taking the drugs, my family took our new dog, Chester, for a walk in the Beach neighbourhood of Toronto. As we strolled along the boardwalk, he snatched a peanut butter sandwich clean out of a little boy’s hand. “It was the first time we’d seen you smile in three months,” my dad told me recently. Over the next few months, my sadness lifted. My toxic thoughts became more manageable. The nausea dissipated, and I started eating again. I switched schools, made new friends, and slowly, cautiously, returned to normal life. The drugs buoyed me up from cataclysmic depression to relatively stable, low-boiling anxiety.

The drugs came with some obsessive-compulsive side effects. I picked the skin on my face and limbs like a crystal meth addict, burrowing beneath the flesh to create welts and sores. I also developed a facial tic, wherein I’d scrunch up my nose until it ached. (Even when I think about it now, the urge to scrunch is hard to resist.) My doctor prescribed even more drugs: clomipramine and imipramine, two remnants of the old tricyclic class of antidepressants.

My parents weighed the potential risks of this cocktail against what they could only imagine would happen if I continued along my destructive path. My doctor, meanwhile, hoped that by staving off anxiety and depression at an early age, my brain might lay down permanent pathways to combat patterns of dysfunctional thinking. Really, no one knew what to expect. “We were totally in the wilderness about child and adolescent psychiatry,” explains Dean Elbe, a clinical pharmacist who specializes in child psychiatry at the BC Children’s Hospital, in Vancouver. “All we could do was extrapolate from what we saw in adults.”

We still don’t really know anything about the long-term effects of antidepressants on adolescent development. There have been no long-term studies, partly because of logistics, and because the US Food and Drug Administration and Health Canada require pharmaceutical companies to prove only that their medications are better than placebos over the short term. One study found that extended exposure to fluoxetine (the generic form of Prozac) in some young mice led to anxiety-like behavior recurring when the mice were exposed again to the drug as adults.

But the most profound and pervasive fear—among adults, among parents of affected kids, and among those kids themselves—is that antidepressants will somehow alter the patient’s essential identity. In Is It Me or My Meds: Living with Antidepressants, Boston-based sociologist David A. Karp explains, “Psychotropic drugs have as their purpose the transformation of people’s moods, feelings, and perceptions. These drugs act on—perhaps even create—people’s consciousness and, therefore, have profound effects on the nature of their identities.”

This kind of thinking taps into one of the paramount tensions of mental illness: the blurred line between pathology and personality. How much of what we feel is the result of an illness? How much is our so-called identity? Though scientists still believe neurotransmitter deficiencies affect mental health, they’ve also implicated a whack of other factors, including the environment, stress, and physical health. Together with the mysterious chemical voodoo taking place in our bodies, those factors spin in an endless feedback loop that makes it impossible to source mental illness. It stands to reason that drugs meant to treat an imbalance in serotonin might bleed beyond their reach, altering who we are as long as we’re on them.

It is a fear that metastasizes in the context of adolescence—a period we mythologize as an activation stage, during which a person carves out his or her identity and individuality. Some people argue that adding antidepressants to this primordial soup could thwart the development of a predestined selfhood, replacing it with a synthetic copy. Katherine Sharpe, an American journalist who started taking antidepressants at eighteen, reflects at length on this issue in her 2012 book, Coming of Age on Zoloft: How Antidepressants Cheered Us Up, Let Us Down, and Changed Who We Are. “When I first began to use Zoloft, my inability to pick apart my ‘real’ thoughts and emotions from those imparted by the drug made me feel bereft,” she writes. “The trouble seemed to have everything to do with being young.” One of the dozens of fellow trailblazers she interviews for the book—a twenty-eight-year-old writer also named Emily—puts her finger on the angst: “I wonder, if I’d never gotten antidepressants, who would I be? . . . Maybe I messed with who I really am by changing my body chemistry.”

That potential identity shift is, of course, a major reason many adolescents resist medication. It’s impossible to know how many, but we all have friends, or friends of friends, who have balked at cheating what they see as an essential truth of their lives by taking an antidepressant. When Geoffrey Cohane, a psychologist in Concord, Massachusetts, tracked the psychological barriers to adolescent antidepressant use while working on his 2008 dissertation, he found issues of identity chief among them. “Antidepressants could make you behave in ways that aren’t really you,” reported one of his study participants. Another pointed out that “it’s already so hard to figure out what your personality is, and antidepressants would make that even harder.”

After all, existential angst isn’t the exclusive domain of those with mood disorders. It isn’t even exclusive to adolescents. From time immemorial, humanity has been preoccupied with questions of identity, the consistent self that persists from one moment to the next. Philosophers trace this obsession back to Plato, who espoused what is known as the strict theory of soul—the idea that we all have a wispy, incorporeal core that persists independent of the body. In his dialogue Phaedo, which depicts the death of Socrates, Plato went further, reasoning that we should all look forward to death as a chance to free the exalted soul from its bodily shackles. That notion was adopted by the early Christians, who used the soul as a crutch to assuage the fear of an indeterminate afterlife.

Yet long after many of us have shed the notion of the inextinguishable soul, the desire to taxonomize and label ourselves continues. We scour horoscopes for insights into our astrological constitutions. We worry ourselves with Myers-Briggs psychometrics, trying to nail down our Jungian archetypes. We invent new racial identities, gender identities, generational identities, all in the quest to know who we are in this world. But what happens when that question is rigged from the outset?

The Platonic notion of the self began to dissipate in the seventeenth and eighteenth centuries, when philosophers developed new concepts of identity. Among them was a materialistic approach, which linked the self to a physical system of organic cells and molecules—you are your body. The empiricist John Locke then updated that concept for the Enlightenment, linking the self to the mind, or, more specifically, to consciousness. “For, since consciousness always accompanies thinking,” he wrote in his 1689 manifesto, An Essay Concerning Human Understanding, “and it is that that makes every one to be what he calls self, and thereby distinguishes himself from all other thinking things; in this alone consists personal identity, i.e. the sameness of a rational being.”

But while Locke takes persistent consciousness as a universal given, such mooring was never available to me. According to one popular psychological model, “personality” depends on five major factors: openness to experiences, conscientiousness, extraversion, agreeableness, and neuroticism. In adolescence, these traits become more consistent and predictable; they draw out a blueprint for how we see ourselves and respond to certain situations. When I was a teenager, I never had the opportunity for my personality to settle into that equilibrium. I was constantly spiking and sinking on antidepressants, those big five personality traits firing out of control like a pinball. In the years immediately following my breakdown, the little pills made it possible for me to pick up where I left off, except in place of the friendly, albeit anxious, kid I had been was a sensitive, snapping turtle of a preteen. In high school, the surliness softened, but my social fears intensified. The friends I’d made in middle school, a group of funny, eccentric girls, began to act like teenagers. I was a bookish introvert with a mood disorder; not surprisingly, textbook adolescent hedonism made me uncomfortable. Despite my friends’ kindness, patience, and loyalty, I couldn’t trust them. I was sure they’d phase me out, having decided I wasn’t worth the trouble. I replayed every conversation in my head, punishing myself for the stupid things I’d said. If I hadn’t spoken to them that day, I became consumed with the fear that they were mad at me. Other times, I was engaged, buoyant, even confident—bigger than those feelings of doubt and depression. It all depended on the time of year, or the time of day, or if I’d taken my Zoloft in the morning or with dinner.

When I was sixteen, after more than five years on the medication, I decided it was more trouble than it was worth. My appetite had increased, and I was gaining weight. It caused debilitating heartburn and digestive issues. It made me sweat profusely. More than anything, perhaps, I wanted to know who I was off the drugs. The first couple weeks after quitting, I felt great. My anxiety was manageable, the kind I imagined normal people coped with every day. Then, seemingly overnight, it all came rushing back: the nausea, the blind panic, the invasive and oppressive thoughts. I found myself crying every morning before going to work as a camp counsellor. I completely shut out my friends. By the end of summer, I was on Celexa.

I realized then that I’d likely be on some form of antidepressant for the rest of my life. And I have been—about six different kinds. For the first two or three years on a new medication, my sensitivity ripens into empathy, while my anxiety, reined in rather than eliminated, keeps me ambitious, active, and conscientious. Inevitably, however, the meds stop working, and something triggers another breakdown. After more than a decade of navigating this unpredictably undulating emotional landscape, I had two major insights. First, I realized I couldn’t rely on drugs alone, and began cognitive behavioural therapy, or CBT, building my mind’s capacity to discern and defuse negative thoughts. Second, although I developed my trademark tastes—Victorian novels, dogs, Diet Coke—I found that my personality had settled into impermanence. I comfortably alternate between introvert and social butterfly, solemn and ebullient, confident and insecure.

The upshot is that, except for that early itch to go off the meds, I’ve never troubled myself with the problem of my true identity. But I suspect others soon will. Once again, my current medication—Cymbalta, which may inhibit reuptake of both serotonin and norepinephrine—is pooping out, and it’s time for a switch. I’m dreading the detox. It will take at least six weeks to wean myself off the drug, during which I’ll endure physical withdrawal symptoms akin to a bad flu. It will take another month or so after that to build up my full dose of the new prescription, a drug called Cipralex. Throughout, I’ll face the inevitable intensification of anxiety and depression. Questions of identity—surely a part of the intractable stigma that surrounds mental illness—will register on the faces of everyone I meet. They’ll suddenly have reason to wonder if I’m really me, even if I don’t.

“If you got into a car accident, and the doctor told you he could save your brain by transplanting it into another person’s body, you’d still be you.” This is James Giles, a Vancouver-born philosopher and psychologist currently based in Denmark, and the author of the 1997 book No Self to Be Found: The Search for Personal Identity. When I asked him about theories of identity, he presented me with that thought experiment—perhaps not the wisest choice for a phobic, but which nevertheless illustrates how the body is irrelevant to selfhood. As for Locke’s theory, Giles argues that consciousness is a fickle constant—people forget things, invent new memories, rewrite history. For him, Locke’s notion of the self depends on an unreliable narrator.

In place of persistent consciousness, Giles espouses something he calls the no-self theory, which is not really a theory about the self at all, but rather a dismissal of all such theories as “inherently untenable.” Its roots run just as deep as the concept of identity, too. “The Buddha was the first person who rejected the idea of the self as a delusion,” Giles tells me. “People create the idea of a permanent self, which causes us to grasp at things that are transient. He suggested that once we relinquished the notion of the permanent self, then we’re able to let go of things like self-pride, embarrassment, and vindictiveness.” Through meditation and breathing exercises, Buddhists aim to grasp the Three Characteristics of Existence: anicca (impermanence), dukkha (suffering), and anatta (the absence of a self).

While I’m not on that particular path, it does sound familiar. “I have thoughts, but I am not my thoughts,” is a typical refrain in CBT. And, as in Buddhism, the reward for doing your homework is ostensibly greater happiness. I can’t speak to the viability of that contract—not yet, anyway. What I do know is that, if I subscribed to popular notions of essentialized selfhood, my true identity would look like a feverishly anxious mass of phobias and self-loathing. Had I stuck with that girl, I’d be either in a padded cell or dead.

The issue of identity is like an M. C. Escher print: answers beget questions, solutions create problems. But Julian Baggini, a writer and philosopher in Bristol, United Kingdom, who specializes in the study of personal identity, put me on to a useful metaphor. It is based on the “bundle theory” outlined in 1739 by David Hume, who argued that the idea of the self arises from our collection of thoughts, memories, and experiences. The body, he wrote, is “nothing but a bundle or collection of different perceptions, which succeed each other with an inconceivable rapidity, and are in a perpetual flux and movement.” Baggini’s version goes like this: Everything in the universe is made up of parts. Consider a water molecule. Or a watch. We don’t think of the watch as something separate from its parts, so why do we think that of the self?

I don’t because I can’t. I’ve simply had to accept that I am a ramshackle bricolage of my experiences: my happy (albeit anxious) childhood, my pubescent breakdown, my fraught teen years, and my ever-evolving adult personality, with antidepressants being merely another cog in the wheel. To others, I might argue that there are a billion possible selves, just as there might be a billion possible universes, their forms determined by a random pastiche of molecules and atoms, decisions and impulses. It’s quite possible that my eighteen years of antidepressants have steered me in a new direction, made me a different person, changed the way I think and feel and relate. Luckily, that’s the person I want to be.

This appeared in the March 2015 issue.

Emily Landau Emily Landau is an associate editor at Toronto Life and a former Walrus intern. Adrian Forrow Adrian Forrow ( @AdrianForrow ) has contributed to The New Yorker, and Bloomberg View.