A structural MRI marker predicts individual differences in impulsivity and classifies patients with...

Area of Science:

• Neuroscience
• Psychiatry
• Radiology

Background:

• Impulsivity and delay discounting are key features of psychiatric and neurodegenerative disorders.
• The neurobiological underpinnings of these traits remain incompletely understood.

Purpose of the Study:

• To identify a structural magnetic resonance imaging (MRI) signature linked to delay discounting in healthy adults.
• To validate this signature in patients with behavioral variant frontotemporal dementia (bvFTD), a condition marked by impulsivity.

Main Methods:

• A machine-learning algorithm predicted individual delay discounting rates from whole-brain grey matter density in healthy adults (Study 1).
• The identified signature was tested for validity in a separate group of healthy adults (Study 2) and for clinical relevance in bvFTD patients and controls (Study 3).

Main Results:

• The structural impulsivity signature (SIS) predicted delay discounting with a cross-validated correlation of r=0.35 in Study 1.
• While not directly correlating with discounting in Study 2, the SIS correlated with trait urgency (impulsivity) in both healthy adult studies.
• In bvFTD patients, the SIS accurately differentiated them from controls (81% accuracy) and correlated with discounting rates and disinhibition severity.

Conclusions:

• A novel structural brain pattern, the Structural Impulsivity Signature (SIS), has been identified.
• The SIS predicts individual differences in impulsivity and shows potential as a diagnostic marker for bvFTD and other impulsivity-related disorders.