NR 547 Week 3 Diagnostic Formulation Example

Diagnostic Formulation: Why a 24-Year-Old Chemistry Student Became Depressed in the Second Semester of a Doctoral Program, and Why the Name That Best Explains It Is Bipolar II Disorder

Student Name

College of Nursing, Chamberlain University

NR 547: Differential Diagnosis in Psychiatric-Mental Health Across the Lifespan

Instructor Name

Month Day, Year

Diagnostic Formulation: Why a 24-Year-Old Chemistry Student Became Depressed in the Second Semester of a Doctoral Program, and Why the Name That Best Explains It Is Bipolar II Disorder

Why This Person, Why Now

The student's depression began in the fifth week of the second semester of a chemistry doctoral program, three weeks after a meeting in which the advisor said the student's first project had failed and would need to be restarted. That meeting did not cause the illness, but it arrived at a moment when three other things had already been building. Sleep had been irregular for months, with nights of four or five hours before deadlines followed by weekends of twelve. Those short nights had been made possible by a friend's amphetamine tablets, taken two or three days a week for about 14 months. And the student carries a family loading for mood disorder: a parent treated with lithium for "highs and lows." Against that background, a sharp blow to the student's sense of competence in the one area where the student had always excelled was enough to tip a vulnerable mood system into a depressive episode.

The argument of this formulation is that the timing, the shape of the episode and the family history are all better explained if the underlying condition is a bipolar illness, and that the stimulant use and sleep disruption are best understood as forces acting on that vulnerability rather than as the cause.

History in Argued Order

The most important piece of history came not from the student but from the student's older sibling. Two summers ago, before the student had used any stimulant, the student spent about five days on three or four hours of sleep a night with no sense of fatigue, spoke quickly, began three projects in a week, including a photography business, and spent about $1,800 on camera equipment, which was out of character for someone who is usually careful with money. In the student's memory it was "a really good week" and it went unmentioned until the student was asked directly about the sibling's account. No one sought help, and the student's summer research placement continued. The period ended on its own and was followed, a few weeks later, by about a month of low mood that the student had dismissed as a slump.

The family history makes that period harder to dismiss. A parent was treated with lithium in their thirties, which strongly suggests bipolar disorder in a first-degree relative.

The stimulant history matters because it complicates both halves of the picture. Stimulants can cause elevated mood and reduced need for sleep, and the crash afterward can mimic depression. The student started using them 14 months ago, well after the summer episode. In the past five weeks, the student reports only four days of use, all in the first week.

The current episode, set out in the criteria mapping, includes low mood, loss of interest, sleeping ten to eleven hours, increased appetite with weight gain, slowed thinking, fatigue, guilt about letting the lab down and passive thoughts of not existing.

Observations

The student arrived on time, dressed casually with unwashed hair, and sat still with little movement of the hands. Speech was slow and quiet with long pauses before answers, and the student often trailed off mid-sentence. The student described mood as "flat and heavy" and affect was constricted, brightening only briefly when talking about climbing. Thought process was linear. There were no hallucinations or delusions. The student acknowledged a passive wish to be gone, denied any plan or intent and named the sibling and a close friend as reasons to stay safe. Attention was reduced, with errors on serial sevens after the third subtraction. Insight was partial: the student recognized being depressed but did not see the summer period as a problem.

Predisposing, Precipitating, Perpetuating and Protective Factors, Connected

The predisposition is biological and familial: a first-degree relative with probable bipolar disorder, and the student's own earlier period of elevated mood. The precipitant was the failure of the first project, landing on a student whose identity rests heavily on academic success. What keeps the episode going is a loop: hypersomnia and low energy make lab work harder, missed work deepens the guilt and sense of failure, and withdrawal from the running club and climbing removes the activities that used to regulate mood and sleep. The stimulant pattern, though currently paused, perpetuates the underlying instability by cycling sleep between extremes.

The protective factors are real. The sibling is closely involved and consented to help. The student has no history of suicide attempts, no access to firearms and no heavy alcohol use. The student is willing to engage, attended both interviews and agreed to stop using the friend's tablets while the assessment continues.

The Differential, Compressed

Three alternatives were genuinely live. Major depressive disorder would fit the current episode, but it cannot absorb the summer period, which, if accurately described, rules it out. A substance-induced depressive disorder would fit if the low mood were confined to the days after stimulant use, but the episode has been continuous for five weeks with only four days of use at its start. Stimulant-induced mood elevation could explain an elevated period, but the summer period came before any stimulant use. Medical causes, including thyroid disease and anemia, are being checked, and the Week 4 analysis addresses them in detail. The Mood Disorder Questionnaire, a screening tool rather than a diagnostic one (Hirschfeld et al., 2000), was positive on items but borderline overall, which is common when hypomania is brief.

Base rates argue for keeping the bipolar question open rather than against it. A national survey estimated the lifetime prevalence of bipolar spectrum disorders in American adults at about 4%, with bipolar II and subthreshold forms together more common than bipolar I (Merikangas et al., 2007). In a young adult with a depressive episode and a first-degree relative with bipolar disorder, the prior probability is considerably higher than in the general population.

The Diagnosis

The diagnosis that best explains this presentation is bipolar II disorder, with the present depressive episode rated moderate to severe, held as provisional pending the laboratory results and confirmation that the summer period met the duration and severity required for a hypomanic episode (American Psychiatric Association, 2022). Nonmedical stimulant use is recorded as a separate problem whose severity needs assessment.

The diagnosis matters because it changes what should be prescribed. An antidepressant alone, reasonable for major depressive disorder, carries a risk of triggering hypomania or rapid cycling in bipolar disorder. Holding the diagnosis as provisional rather than settling on major depressive disorder by default is the most important safety decision in this formulation.

References

American Psychiatric Association. (2022). Diagnostic and statistical manual of mental disorders (5th ed., text rev.). https://doi.org/10.1176/appi.books.9780890425787

Hirschfeld, R. M. A., Williams, J. B. W., Spitzer, R. L., Calabrese, J. R., Flynn, L., Keck, P. E., Jr., Lewis, L., McElroy, S. L., Post, R. M., Rapport, D. J., Russell, J. M., Sachs, G. S., & Zajecka, J. (2000). Development and validation of a screening instrument for bipolar spectrum disorder: The Mood Disorder Questionnaire. American Journal of Psychiatry, 157(11), 1873-1875. https://doi.org/10.1176/appi.ajp.157.11.1873

Merikangas, K. R., Akiskal, H. S., Angst, J., Greenberg, P. E., Hirschfeld, R. M. A., Petukhova, M., & Kessler, R. C. (2007). Lifetime and 12-month prevalence of bipolar spectrum disorder in the National Comorbidity Survey Replication. Archives of General Psychiatry, 64(5), 543-552. https://doi.org/10.1001/archpsyc.64.5.543