Neural Reward Processing Mediates the Relationship between Insomnia Symptoms and Depression in Adolescence.
OBJECTIVE
Emerging evidence suggests that insomnia may disrupt reward-related brain function-a potentially important factor in the development of depressive disorder. Adolescence may be a period during which such disruption is especially problematic given the rise in the incidence of insomnia and ongoing development of neural systems that support reward processing. The present study uses longitudinal data to test the hypothesis that disruption of neural reward processing is a mechanism by which insomnia symptoms-including nocturnal insomnia symptoms (NIS) and nonrestorative sleep (NRS)-contribute to depressive symptoms in adolescent girls.


METHODS
Participants were 123 adolescent girls and their caregivers from an ongoing longitudinal study of precursors to depression across adolescent development. NIS and NRS were assessed annually from ages 9 to 13 years. Girls completed a monetary reward task during a functional MRI scan at age 16 years. Depressive symptoms were assessed at ages 16 and 17 years. Multivariable regression tested the prospective associations between NIS and NRS, neural response during reward anticipation, and the mean number of depressive symptoms (omitting sleep problems).


RESULTS
NRS, but not NIS, during early adolescence was positively associated with late adolescent dorsal medial prefrontal cortex (dmPFC) response to reward anticipation and depressive symptoms. DMPFC response mediated the relationship between early adolescent NRS and late adolescent depressive symptoms.


CONCLUSIONS
These results suggest that NRS may contribute to depression by disrupting reward processing via altered activity in a region of prefrontal cortex involved in affective control. The results also support the mechanistic differentiation of NIS and NRS.
University of Pittsburgh, Pittsburgh, PA.
Melynda D
MD
Casement
University of Chicago, Chicago, IL.
Kate E
KE
Keenan
University of Pittsburgh, Pittsburgh, PA.
Alison E
AE
Hipwell
University of California, Davis, Davis, CA.
Amanda E
AE
Guyer
University of Pittsburgh, Pittsburgh, PA.
Erika E
EE
Forbes
D000293:Adolescent; D041923:Adolescent Development; D000339:Affect; D017028:Caregivers; D003863:Depression / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology*; D003866:Depressive Disorder / Q000175:diagnosis / Q000503:physiopathology / Q000523:psychology; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D017397:Prefrontal Cortex / Q000503:physiopathology; D011446:Prospective Studies; D012201:Reward; D012890:Sleep; D007319:Sleep Initiation and Maintenance Disorders / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology*
adolescence; affective processing; depression; fMRI; insomnia; nonrestorative sleep