Diagnostic interview for genetic studies. Rationale, unique features, and training. NIMH Genetics Initiative

Area of Science:

• Psychiatry
• Genetics
• Clinical Psychology

Background:

• Assessing major mood and psychotic disorders requires reliable diagnostic tools.
• Genetic studies necessitate standardized and accurate data collection methods.
• Existing interviews may not adequately capture illness course, comorbidity, or spectrum conditions.

Purpose of the Study:

• To report the development and reliability of the Diagnostic Interview for Genetic Studies (DIGS).
• To evaluate the DIGS's utility in assessing major mood and psychotic disorders and related conditions for genetic research.
• To assess the inter-rater and test-retest reliability of the DIGS for specific psychiatric diagnoses.

Main Methods:

• The Diagnostic Interview for Genetic Studies (DIGS) was developed by NIMH Genetics Initiative investigators.
• A two-phase test-retest reliability study was conducted using DSM-III-R criteria.
• Interviews were administered for major depression, bipolar disorder, schizophrenia, and schizoaffective disorder, with algorithmic scoring and best-estimate diagnoses.

Main Results:

• Algorithmic scoring demonstrated excellent reliability (0.73–0.95) for major depression, bipolar disorder, and schizophrenia.
• Reliability for schizoaffective disorder was lower due to disagreements in estimating the duration of mood syndromes relative to psychosis.
• A best-estimate process incorporating medical records and collateral information is anticipated to enhance diagnostic accuracy.

Conclusions:

• The DIGS is a valuable tool for psychiatric genetic research, offering polydiagnostic capacity and detailed phenomenological assessment.
• The interview's reliability is strong for several key disorders, with potential improvements through a best-estimate diagnostic process.
• The DIGS facilitates comprehensive data gathering crucial for understanding the genetic underpinnings of major psychiatric disorders.