Top-down or bottom-up: Contrasting perspectives on psychiatric diagnoses

Area of Science:

• Psychiatry
• Medical Genetics
• Syndromic Disorders

Background:

• Clinical psychiatry faces challenges integrating expanding medical genetics knowledge.
• Current research on genetic underpinnings of mental disorders often shows heterogeneous results due to rigid diagnostic categories.
• The assumption of clear boundaries for nosological categories may hinder understanding genetic influences.

Purpose of the Study:

• To explore the relationship between genetic abnormalities and psychiatric symptoms using a bottom-up approach.
• To evaluate the adequacy of traditional top-down diagnostic taxonomies in light of genetic findings.
• To illustrate how genetic syndromes present with diverse psychiatric phenotypes.

Main Methods:

• Analysis of genetic data from prevalent syndromes (Fragile X, Prader-Willi, 22q11 deletion, Noonan) and rare chromosomal abnormalities.
• Examining psychiatric symptoms associated with these genetic conditions.
• Applying a bottom-up approach to understand genetic contributions to psychiatric phenotypes.

Main Results:

• Genetic abnormalities are frequently associated with a probability of developing various nonspecific psychiatric symptoms, not a single disorder.
• Psychotic, mood, anxiety, and autistic features are observed across a wide range of genetic syndromes.
• A psychiatric phenotype encompasses not only symptoms but also developmental, neurocognitive, and physical characteristics.

Conclusions:

• The traditional categorical approach in psychiatry may be less adequate when substantial etiological data are available.
• Genetic factors contribute to a broad spectrum of psychiatric symptoms and characteristics, challenging discrete diagnostic boundaries.
• Understanding the psychiatric phenotype requires integrating genetic, developmental, neurocognitive, and physical data.