Differential diagnosis, part two: timing, history and course

Transcript

RyanTwelve days ago, a 34-year-old woman was injured in a highway crash. Now she's on a hospital trauma unit, and she's having nightmares, flashbacks of the impact, and panic whenever she thinks about riding in a car.

SoheeAnd the surgeon turns to the consulting psychologist and asks: does she have post-traumatic stress disorder?

RyanIt's a fair question. Everything about it sounds like PTSD. Except one thing: the calendar.

SoheeWelcome to EPPP Prep, the podcast. I'm Sohee.

RyanI'm Ryan. Last time, differential diagnosis meant checking the body and substances. Today it's time. How long symptoms have lasted, what's happened before, and how the pattern unfolds. Same sources as last time: SAMHSA's public condition summaries.

SoheeLet's start with our trauma patient. SAMHSA describes PTSD as a real disorder that develops when a person has experienced or witnessed a scary, shocking, terrifying or dangerous event.

RyanAnd then the key line: to be considered for PTSD, signs and symptoms must last more than a month, and be severe enough to interfere with school, work or relationships.

SoheeSo at twelve days, PTSD can't be considered yet, no matter how intense the symptoms are. That doesn't mean she's fine, or that her distress isn't real. It means this label doesn't fit yet.

RyanNow, the wrong answers in our practice items are built from true-sounding myths. One says PTSD is unlikely because symptoms usually start months after the event.

SoheeBut SAMHSA says PTSD starts at different times for different people. Signs may start soon after a frightening event and then continue. Other people develop new or more severe signs months or even years later. So early onset doesn't rule it out.

RyanAnother myth: PTSD requires repeated trauma, not a single event. But SAMHSA's own list of events includes a single bad accident, along with war, a natural disaster, sexual assault and physical abuse.

SoheeAnd you can get PTSD after living through or seeing a traumatic event. Witnessing counts. It can also happen to anyone, even children.

RyanThe third myth is the opposite mistake: PTSD can be diagnosed now, because both a trauma and symptoms are present. That ignores the duration requirement.

SoheeSAMHSA's symptom list is worth hearing once: flashbacks, trouble sleeping or nightmares, feeling detached, angry outbursts, avoidance of reminders, negative beliefs about oneself or others, feeling very vigilant, being quick to startle. And it notes that symptoms of anxiety, depression and substance use are also seen in people with PTSD.

RyanLet's pause and think. A bank teller was held at gunpoint during a robbery 9 days ago. She has trouble sleeping, startles at the door chime, and has missed several shifts. Her manager asks whether she has PTSD. What's most accurate?

SoheePTSD can't be considered yet. Nine days is short of the more-than-a-month requirement, even though her symptoms are real and already affecting work.

RyanSame answer for a man at a disaster recovery center two weeks after a tornado destroyed his street, with nightmares, constant alertness and poor concentration. A natural disaster can lead to PTSD. But at two weeks, the duration hasn't been met.

SoheeAnd if those symptoms do persist, SAMHSA notes that PTSD symptoms may last months to years. That's exactly why it's worth following up, rather than closing the file.

RyanOkay, depression, where time frames come in a few sizes. SAMHSA says that to be diagnosed with major depressive disorder, some of the listed signs and symptoms must be present nearly every day for at least two weeks.

SoheeThen persistent depressive disorder, which SAMHSA describes as a low mood lasting two or more years in adults, and at least one year in children and adolescents. A person with it may have episodes of major depression along with periods of less severe symptoms.

RyanThen seasonal affective disorder. SAMHSA says it isn't considered a separate disorder, but a type of depression. It usually occurs during the fall and winter months, when there's less sunlight and the days get shorter, and it usually lifts during spring and summer.

SoheeSo: two weeks, two years, one year for young people, and a seasonal pattern tied to fall and winter. Those are the clocks.

RyanNow the most important history question in this whole area. Before you call something depression, ask about the highs.

SoheeHere's the case. A 29-year-old woman comes to therapy with 3 weeks of sadness, hopelessness, and sleeping much more than usual, which began in early summer. Two years ago, she went a week with almost no sleep, felt invincible, talked nonstop, and spent her savings on impulsive purchases, which led to a hospital stay.

RyanToday she looks depressed. But that week two years ago matches SAMHSA's description of a manic episode almost line for line.

SoheeSAMHSA's list for a manic episode includes intense feelings of euphoria, excitement or happiness. Excessive energy. Insomnia or restlessness, meaning a decreased need for sleep. Speaking fast or being unusually talkative. Racing or jumbled thoughts. Inflated self-esteem. And impulsive, uncharacteristic or risky things like unsafe sex or spending a lot of money.

RyanAnd SAMHSA defines bipolar I disorder as having a history of at least one manic episode, sometimes with depressed or hypomanic episodes as well.

SoheeSo the diagnosis that fits her full history is bipolar I disorder. One past manic episode is enough.

RyanLet's walk the distractors, because each one fits a piece. Major depressive disorder fits the current episode, but not the past manic week. And SAMHSA notes that bipolar disorder is different from depression, but a person with bipolar disorder can have episodes of major depression.

SoheePersistent depressive disorder needs two or more years of low mood in adults, and her episode is three weeks old. Seasonal affective disorder usually comes in fall and winter, and hers began in early summer.

RyanWhile we're here, SAMHSA's other bipolar types. Bipolar II disorder involves highs that are less extreme, called hypomanic states, and its depressive episodes may be as severe as those in major depressive disorder. Cyclothymic disorder is more chronic mood instability, with highs and lows not as long, severe or frequent as in bipolar I or II.

SoheeSo the difference between the types, in SAMHSA's words, is how extreme the mood states are and how long they last. Which is, once again, a question about time and history.

RyanAnd notice where that history came from in our practice items: the patient's own account of the past, or a roommate, or a spouse. A collateral informant may remember the manic stretch the patient doesn't mention.

SoheeSecond pause and think. In an integrated primary care clinic, a 41-year-old man reports a month of low energy, loss of interest and thoughts of death that began in June. His wife adds that 3 years ago he had several weeks of intense euphoria, little need for sleep, racing thoughts and risky spending that cost him his job. Best-fitting diagnosis?

RyanBipolar I disorder. The past stretch matches a manic episode, and people with bipolar disorder can also have episodes of major depression like the current one.

SoheeAnd since he mentions thoughts of death, don't treat that only as a diagnostic clue. SAMHSA lists thoughts of death and suicide among the signs of a depressive episode, and the same page says that anyone who is struggling or in crisis can call or text 988.

RyanOne more time-and-development rule, from a different condition. SAMHSA says that for symptoms to be diagnosed as attention deficit hyperactivity disorder, they must be out of the normal range for a person's age and development.

SoheeSo the yardstick isn't only how long. It's also compared with what's typical for this person's stage of life.

RyanLet's recap. PTSD: symptoms must last more than a month and interfere with school, work or relationships. Onset can be soon after the event or months to years later, and a single event, even one you witnessed, can be enough.

SoheeMajor depressive disorder: symptoms nearly every day for at least two weeks. Persistent depressive disorder: two or more years in adults, one year in children and adolescents. Seasonal affective disorder: usually fall and winter, a type of depression.

RyanBipolar I: at least one manic episode, ever. Bipolar II: hypomanic highs. Cyclothymic: chronic, milder ups and downs. And always ask about past highs before settling on depression.

SoheeIf you're someone who has felt your own mood shift around this exam, please be gentle with yourself. Studying these conditions can stir things up. Taking care of yourself is part of the preparation, not a break from it.

RyanAnd if you ever find yourself in crisis, you can call or text 988 in the United States and Canada. We'll see you next time on EPPP Prep.

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