Investigating the Shared and Divergent Neuroanatomical Features of Attentional Deficits in Adolescents

Cognitive disengagement syndrome (CDS), formerly known as sluggish cognitive tempo, is characterized by hypoactivity or slowed behavior, mental fogginess or confusion, excessive sleepiness, and daydreaming. CDS and the predominantly inattentive (IN) presentation of attention-deficit/hyperactivity disorder (ADHD) are frequently co-occurring albeit separable constructs, each associated with unique constellations of functional impairments. The current study aims to identify their shared and divergent neurobiological correlates.

A total of 181 adolescents (mean age =13.9 years, SD = 2.2 years) were recruited from the Colorado Learning Disabilities Research Center twin study. Relationships between attentional symptom dimensions (CDS and IN) and brain volume were examined, controlling for age, sex, and average cortical volume. Procedures were repeated in an outside sample of 292 adolescents (mean age = 16.8 years, SD = 1.4 years) using a 2-item measure of CDS.

Higher levels of CDS symptoms were associated with reduced volume within the left ventral parietal, temporo-parietal, and temporal regions, regions that fall within the ventral attention network. CDS and IN symptoms were significantly associated with gray matter volume in portions of the dorsal attention and default mode networks in opposite directions. Higher levels of CDS symptoms were associated with reduced volume in the left superior and inferior parietal lobules and left frontal portions of the default mode network, whereas IN symptoms were positively correlated with volume in these areas. Several findings were consistent in the outside sample.

Results from the current study provide novel insights into the neurobiological basis of CDS. They suggest that both CDS and IN symptoms are associated with alterations in brain systems that exert top-down attentional control, though likely for differing reasons. The current study enhances understanding of adolescent attentional deficits.

This study used brain magnetic resonance imaging (MRI) scans of 2 samples of adolescents with a total of 473 participants to explore how symptoms of two attentional constructs-attention-deficit/hyperactivity disorder (ADHD) inattention and cognitive disengagement syndrome (CDS)-relate to brain structure. The authors found that these symptoms are linked to differences in brain volume in attention-related areas, but in opposite ways: inattention was associated with greater volume, while cognitive disengagement was associated with reduced volume in the same regions. These findings suggest that although these attention difficulties often occur together, they may have different underlying brain mechanisms.