How Clinical Interviews Help Diagnose Mental Illness

Distressed woman holding her hand to her head in a counselling session with a male therapist

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A clinical interview is a tool that helps physicians, psychologists, and researchers make an accurate diagnosis of a variety of mental illnesses, such as obsessive-compulsive disorder (OCD). There are two common types: structured clinical interviews and clinical diagnostic interviews.

Structured Clinical Interviews

The gold standard for structured clinical interviews is the Structured Clinical Interview for DSM-5, also known as SCID. It is a semi-structured interview guide that is administered by a psychologist or other mental health professional who is familiar with the diagnostic criteria of mental health conditions.


Structured clinical interviews have a variety of uses, including:

  • Assessing patients in order to make a diagnosis based on the Diagnostic and Statistical Manual of Mental Health Disorders, 5th Edition (DSM-5)
  • Practice for students going into the mental health field to become better interviewers
  • Research to study certain groups of people who all have the same symptoms or clinical trials

SCIDs can also help determine if you have more than one illness. They contain standardized questions to ensure that each patient is interviewed in the same way.

Since many of the questions concerning diagnostic criteria are subjective (in comparison, for example, to the number on a blood test which may be used to diagnose a physical disorder), a standardized guide such as the SCID helps to make sure studies are looking at people with the same general symptoms.

A structured clinical interview helps to make a largely subjective diagnosis a little more objective.

Types of Questions

The questions on the SCID range from asking about your family and medical history to your illnesses and current complaints, as well as the nature, severity, and duration of the symptoms you have experienced. The questions get very detailed and specific, but not all questions will need answers since the SCID covers a broad range of illnesses, most of which you probably do not have. 

Questions that you may be asked during a structured clinical interview that are specifically about OCD include:

  • Did your symptoms start after a new illness or taking a new drug?
  • What are the specific details of your obsessions and compulsions?
  • How long have you had these obsessions and compulsions?
  • How have these obsessions and compulsions affected your life?
  • Were you physically sick before you started having obsessions and/or compulsions?
  • Were you using drugs before you started having obsessions and/or compulsions?
  • How old were you when these symptoms started?

A SCID can take anywhere from 15 minutes to several hours to complete, depending on the severity and types of your symptoms.

Clinical Diagnostic Interviews

Another valid way to assess and/or diagnose mental illness is by using a clinical diagnostic interview (CDI). CDIs are different in that they involve a conversation, or narrative, between the mental health professional and the patient instead of a list of standardized questions like the SCID entails.

A clinical diagnostic interview takes about two and a half hours, and the mental health professional doing the interview will likely take notes as you talk. A symptom checklist might also be used along with the CDI to help the interviewer make a diagnosis.

Types of Questions

The questions during a CDI are much broader and leave you room to give details. Examples of questions are:

  • What was your childhood like?
  • What is your relationship with your mother/father/siblings like?
  • What was school like for you?
  • What sort of friendships did you have as a child?
  • What have your romantic relationships been like?
  • What is your job and how long have you done it?


You may be wondering if one interview method is better than the other. The short answer is no. In fact, a 2015 study showed that both interview methods are equally valid and useful. Which method a clinician uses will likely depend on the standard of their organization and/or personal preference.

It is extremely important that a thorough method of diagnosis is used, regardless of which interview method your therapist recommends to determine if you are coping with obsessive compulsive disorder or another mental health condition,

Too often, a mental health diagnosis is made without the help of these tools. With the information available on the Internet, people are increasingly self-diagnosing mental health conditions. And with a shortage of mental health providers (plus constraints on time and charges placed by third-party payers), this step is sometimes inappropriately streamlined.

A Word From Verywell

Considering the great effect that OCD and other mental health disorders can have on a person's life, it is imperative that these initial diagnostic interviews are not skipped. Making a precise diagnosis is helpful in determining the type of treatments and therapies which have found to be most effective in clinical studies for that particular diagnosis.

It is also very important to conduct these interviews to get a baseline as to how much the condition is interfering with your life. Progress in mental health can sometimes be slow and often follows the proverbial three steps forward and two steps back trajectory. Understanding exactly what you were coping with at the time you were diagnosed can help your therapist determine if your current therapy plan is working, or if a different approach is needed.

2 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Drill R, Nakash O, DeFife J, Westen D. Assessment of clinical information: Comparison of the validity of a structured clinical interview (the SCID) and the clinical diagnostic interviewJ Nerv Ment Dis. 2015 Jun;203(6):459-62. doi:10.1097/NMD.0000000000000300

  2. Rapp A, Bergman L, Piacentini J, McGuire J. Evidence-based assessment of obsessive-compulsive disorderJ Cent Nerv Syst Dis. 2016;8:13-29. doi:10.4137/JCNSD.S38359

Additional Reading

By Owen Kelly, PhD
Owen Kelly, PhD, is a clinical psychologist, professor, and author in Ontario, ON, who specializes in anxiety and mood disorders.