Table
Three causes of psychosis—and different characteristics of each presentation
| Characteristic | Mood disorder with psychosis | Schizophrenia | Substance-induced psychosis |
|---|---|---|---|
| Acute onset | x | - | x |
| Delusions | x | x | x |
| Disorganized or catatonic behavior | x | x | x |
| Family history of psychosis | x | x | _ |
| Good premorbid function | x | _ | x |
| Hallucinations | x | x | x |
| Negative symptoms | x | x | x |
| Personal history of psychosis | x | x | _ |
| Prodromal and residual symptoms | _ | x | _ |
Relapse: cameras ‘off’ for 1 week
Five days after admission, we discharge Ms. P as her psychosis has improved significantly.
Later that day at the outpatient clinic, Ms. P requests a medication change, voicing fears about haloperidol’s long term side effects and mirtazapine-induced weight gain. Risperidone, 2 mg nightly, and citalopram, 20 mg/d, are started instead.
One week later, Ms. P’s parents again bring her to the ER after police find her sitting in her car, confused and paranoid. She complains that cameras have been set up in her car, and she responds to voices when alone.
On the way to the ER, Ms. P tries to jump from the moving car. She assaults her mother as she stops her from jumping.
Blood pressure is 155/92, heart rate is 82 beats per minute, respiratory rate is 18 breaths per minute, and temperature is 96°F.
On interview, Ms. P admits that she stopped risperidone and citalopram and restarted Xenadrine and phentermine. She also reports orthostasis from risperidone. We again admit her to the acute-care psychiatric unit and restart haloperidol, 1 mg/d, and citalopram, 20 mg/d.
The authors’ observations
Although we knew Ms. P was abusing diet pills, we could have easily ruled out drug-induced psychosis based on her three negative urine drug screens.
The clinical course of Ms. P’s psychosis, however, closely followed her diet pill use—emerging soon after starting phentermine and remitting soon after stopping it. Also:
- she was taking 2 to 3 times the recommended dosage of phentermine for several months. Phentermine is indicated for short-term (a few weeks) treatment of exogenous obesity (BMI ≥27 kg/m2 in persons with hypertension, diabetes, or hyperlipidemia; BMI ≥30 kg/m2 in persons without these risk factors)1
- her BMI was below normal
- her psychosis remains in remission without use of an antipsychotic.
Stimulant medications such as amphetamines and stimulant drugs such as cocaine can produce psychotic symptoms including paranoid delusions, hallucinations, and bizarre behavior. Farrell and colleagues5 found that cannabis and psychostimulants increase the risk of psychosis.
Genetic load could have influenced Ms. P’s response to diet pills, but we have no information to support a genetic predisposition. Also, we saw no clear family history of a formal thought disorder.
The authors’ observations
Urine drug screens can pick up the main drug classes and often their derivatives, but this testing method is limited.2
Urine tests employ assays with semi-quantitative results. A urine sample may contain an abused substance but at levels below the cutoff. Also, because no correlation exists between cutoff levels and drug effect, a patient can have drug-induced symptoms but a negative urine drug screen. This makes detecting a suspected but unknown drug of abuse extremely difficult.
A routine urine screen can detect phentermine and other stimulants, but the phentermine level needed for a positive assay is 50 times that of pure amphetamine.2 Ms. P’s last urine drug screen showed an amphetamine level just under the cutoff.
Use of cocaine—undetectable in urine 3 to 4 days after use—could be considered when drug-induced psychosis is suspected. Ms. P’s psychosis correlated with her phentermine relapse, however, and both she and her ex-boyfriend denied that she uses street drugs.
Obtain specific drug levels when you suspect medication abuse. Request gas chromatography or mass spectrometry to provide a quantitative result and confirm medication abuse.2,3 These tests would have been appropriate for Ms. P once her ex-boyfriend revealed the diet pill abuse.
Detecting diet pill abuse
Use of weight-loss supplements and appetite suppressants is alarmingly common (Box). Many patients suffer adverse effects from diet pills but do not tell their doctors they are using them because they:
- fear the physician will scold them for circumventing his or her advice by obtaining medications online
- sense that obtaining diet pills over the Internet might be illegal
- do not realize the doctor needs to know about nonprescription drug use
- or fear the physician will tell them to stop taking the drug.
Rapid or unexplained weight loss, hypertension, tachycardia, tremors, psychomotor agitation, and hyperalertness could signal diet pill abuse. Emotional lability, such as euphoria during a high and fatigue and dysphoria during withdrawal, also could be indicative. Collateral information from family members or significant others can narrow the differential diagnosis.