Distinguishing Schizophrenia From Substance-Induced Psychosis

An 18-year-old college freshman presents to outpatient psychiatry 1 week after discharge from his second psychiatric hospitalization during his first semester of college.

He arrives with his parents but makes it clear he does not want to be there.

Earlier in the semester, he had been hospitalized for a first episode of psychosis. At that time, he was experiencing auditory hallucinations and paranoid delusions. He believed his phone had been hacked, that campus security was tracking him, and that food in the dining hall was being poisoned. He denied visual hallucinations and did not have symptoms consistent with depression or mania. He had been using high-potency THC vape products daily since starting college.

During that first hospitalization, he was started on risperidone, which he took for several weeks after discharge before stopping it because he did not believe he had a psychiatric illness and did not want to be on medication.

After discontinuing risperidone, he resumed daily cannabis use. Over the next several weeks, his paranoia returned and intensified. He became increasingly suspicious of his roommate and classmates, stopped attending classes, avoided the dining hall, and slept poorly. Toward the end of the semester, campus police were called after he became acutely agitated and destroyed property in his dorm room. He was transported to the emergency department and admitted for a second psychiatric hospitalization.

During the second hospitalization, he was started on olanzapine 10 mg nightly due to agitation.

Now, 1 week after discharge, his parents report that he is “much better.” He is sleeping, eating, and no longer openly accusing people of poisoning him. He has also been abstinent from cannabis for approximately 2 weeks.

The patient complains, however, that has already gained 7 lbs. and feels tired throughout the day. He says olanzapine makes him feel “drugged,” and he does not want to continue taking it.

His parents also ask the central question many families ask after an early psychosis hospitalization:

“Does he really have schizophrenia, or does he just need to stay off marijuana?”

Additional Details

• Collateral history from his parents suggests that his illness did not begin abruptly; over the prior 6-9 months, he had become increasingly socially withdrawn, stopped calling friends from home, rarely left his dorm room, and his grades declined sharply despite previously being a strong student.
• His parents also noticed reduced motivation, decreased emotional expression, impaired hygiene, and difficulty organizing his thoughts. 
• He appeared internally preoccupied and increasingly suspicious when family members asked routine questions.

Medical History

• No significant past medical history. 
• No known family history of psychosis, bipolar disorder, or suicide.
• Emergency department laboratory testing was reportedly unrevealing, including Complete Blood Count (CBC), Comprehensive Metabolic Panel (CMP), Thyroid-Stimulating Hormone (TSH), and urine toxicology positive only for tetrahydrocannabinol (THC). 
• No neuroimaging was performed upon his hospitalizations.

At this intake appointment, it was imperative to review the patient’s medical history and hospitalization records, get collateral information, and spend time interviewing him alone to rule out other substance factors that may not have shown up in a drug screen. This information allowed me to construct a timeline of his cannabis use and symptom onset, which was critical to narrow down an initial diagnosis.

I also completed a thorough risk assessment, particularly because the second hospitalization included agitation and property destruction. I assessed for suicidal and homicidal ideation, command hallucinations, and access to firearms or weapons.

I additionally used screening tools for quantitative measures to establish a baseline and monitor progress over time, including a psychosis rating scale (eg, Brief Psychiatric Rating Scale [BPRS] or the DSM-5 Clinician-Rated Dimensions of Psychosis Symptom Severity [CRDPSS]), the Cannabis Use Disorder Identification Test-Revised (CUDIT-R) to assess cannabis use, and the Patient Health Questionnaire-9 (PHQ-9) to screen for depression. In instances where bipolar disorder remains a consideration, the Young Mania Rating Scale (YMRS) could also be helpful. 

Because he had no indication of seizure activity, I decided not to order an EEG. He also didn’t appear to have any type of central nervous system (CNS) infection, which would be characterized by more of an acute delirious presentation. Further, he did not present with any neurological abnormalities and there was no family history of neurological illnesses, so I didn’t feel a brain MRI was necessary at this intake visit.

His response to antipsychotic medications indicated to me that this was likely a primary psychotic disorder, though I still spent more time pinpointing when he began using marijuana and when the negative symptoms of a thought disorder first occurred.

Based on the information I gathered through thorough assessment, it sounded like schizophrenia; he had negative symptoms that predated the positive symptoms that weren’t picked up on until he started to have auditory hallucinations, paranoid delusions, and eventually agitation. He also didn’t have prominent manic symptoms or a clear-cut history of depression, which ruled out schizoaffective disorder at this point.

Finally, I reviewed his response and adherence to the previous antipsychotic treatments to help guide an appropriate next step for treatment.

Brittany Albright MD, MPH, is a Harvard-trained, triple board-certified psychiatrist with clinical expertise in interventional psychiatry, addiction psychiatry, and obesity medicine. She completed her adult psychiatry residency at the nation’s top ranked program, Massachusetts General Hospital and McLean Hospital and a fellowship in addiction psychiatry at the Medical University of South Carolina, where she serves as an Affiliate Assistant Professor in the Department of Psychiatry & Behavioral Sciences. Dr. Albright is the Founder and CEO of Sweetgrass Psychiatry, South Carolina’s largest physician-owned psychiatry practice with three locations.

Her research and academic work include numerous abstracts presented at national meetings and peer-reviewed manuscripts focused on innovative treatments and psychiatric education. A national speaker and consultant, she serves as President Elect of the South Carolina Psychiatric Association and holds multiple leadership roles with Psych Congress, including co-chair of Psych Congress Elevate and originator of the Private Practice Summit.

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