A Study to Test How BI 3031185 is Tolerated by People With Borderline Personality Disorder or Attention-deficit/Hyperactivity Disorder

Inclusion Criteria:

• Male, female, and non-binary participants, 18 to 45 years of age, both inclusively,at the time of consent

• Meet current Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5) criteria as primary diagnosis as assessed by the Mini InternationalNeuropsychiatric Interview (MINI) at screening for borderline personality disorder (BPD) OR attention-deficit/hyperactivity disorder (ADHD)

• Willingness to abstain from alcohol for 24 h, and all other drugs of abuse includingcannabis for 72 h prior to Visits 2 and 3 (Day -1). Willingness to abstain fromalcohol and cannabis for 72 h after investigational medicinal product (IMP)administration, as well as from all other recreational drugs for the duration of thetrial

• Willingness to abstain from prescribed psychostimulants for 72 h prior to Visits 2and 3 (Day -1) and 24 h following IMP administration Further inclusion criteriaapply

Exclusion Criteria:

• Lifetime diagnosis of schizophrenia, schizoaffective disorder, schizophreniformdisorder, bipolar I disorder, delusional disorder, autism spectrum disorder, orantisocial personality disorder as confirmed by the MINI

• Any other psychiatric disorder that is not currently stable in symptoms andtreatment

• Any substance use disorder within 3 months prior to randomisation (excluding mildalcohol, cannabis, tobacco, and caffeine use disorders); or moderate to severesubstance use disorder within the 6 months prior to randomisation (excluding tobaccoand caffeine)

• Positive drug screen. Participants with positive cannabis drug tests can be includedif they do not meet criteria for moderate or severe cannabis use disorder and theinvestigator determines that use will not be an impediment to trial participation oraccurate data collection

• Concomitant use of psychotropic medication except for the ones below. All otherpsychotropic medications must be washed out at least 30 days or 5 Half-life time (t1/2) (whichever is longer) before the start of Visit 2 (Day -1)

1. A single SSRI (selective serotonin re-uptake inhibitor) or SNRI (selectiveserotonin and norepinephrine re-uptake inhibitor) antidepressant that has beenstable in dose and frequency for >3 months prior to randomisation

2. A single second-generation antipsychotic at a low dose that has been stable indose and frequency for >3 months prior to randomisation (low dose = 1 thorazinedose equivalent or less, which translates to ≤2 mg/day for risperidone, 5mg/day for olanzapine, 75 mg/day for quetiapine, 60 mg/day for ziprasidone, and 7.5 mg/day for aripiprazole)

3. A single sleep medication given as a nightly scheduled medication (not pro renata) stable in agent and dose for >3 months prior to screening. Allowed sleepmedications include: non-benzodiazepine Z sleep medications, antihistamines,melatonin, trazodone, and doxepin

4. Participants taking psychostimulant medication prescribed as per label for ADHDmust stop medication 72 h prior to Visits 2 and 3 (Day -1) and may resume 24 hafter receiving the medication dose on the test day (i.e. 5 days total off ofprescribed psychostimulant for Visit 2 and 5 days off of prescribedpsychostimulant for Visit 3)

• Any documented active or suspected malignancy or history of malignancy within 5years prior to screening, except appropriately treated basal cell carcinoma of theskin or in situ carcinoma of uterine cervix

• A positive result for any active hepatitis

• Previous randomisation in this trial Further exclusion criteria apply