Differential Diagnosis

• Single most likely diagnosis
  • Obsessive-Compulsive Disorder (OCD): The patient's behavior of checking locks multiple times before feeling able to exit the house is a classic symptom of OCD, characterized by recurring, intrusive thoughts (obsessions) and repetitive behaviors (compulsions) that the individual feels driven to perform.
• Other Likely diagnoses
  • Anxiety Disorder: The patient's excessive preparation time and tardiness could be related to generalized anxiety, social anxiety, or specific phobias that interfere with her daily functioning.
  • Attention Deficit Hyperactivity Disorder (ADHD): Although less likely given the specific behaviors described, ADHD could contribute to difficulties with time management, organization, and self-regulation, potentially leading to tardiness and absenteeism.
• Do Not Miss diagnoses
  • Traumatic Brain Injury or Neurodevelopmental Disorders: Although rare, conditions affecting brain development or function could lead to significant difficulties with executive function, including planning, time management, and self-regulation, mimicking or complicating the presentation of primary psychiatric disorders.
  • Substance Use Disorder: Substance abuse could significantly impair an individual's ability to maintain a job due to its effects on motivation, cognitive function, and overall health, and should be considered in the differential diagnosis of any patient with significant functional impairment.
• Rare diagnoses
  • Frontotemporal Dementia: An extremely rare condition in a 19-year-old, frontotemporal dementia could present with significant changes in personality, behavior, and cognitive function, potentially leading to difficulties with employment.
  • Autism Spectrum Disorder with significant executive function deficits: While not uncommon, the specific presentation of autism spectrum disorder with pronounced difficulties in executive functioning (e.g., time management, flexibility) might be considered if other diagnoses are ruled out and there are additional indicators of autism spectrum disorder.