Toward a functional neuroanatomy of dysthymia: A functional magnetic resonance imaging study
Received 25 February 2009; accepted 3 March 2009.
Abstract
Background
Dysthymia is a common mood disorder. Recent studies have confirmed the neurobiological and treatment response overlap of dysthymia with major depression. There are no previous published studies of functional magnetic resonance imaging (fMRI) in dysthymia.
Method
fMRI was used to compare neural processing of 17 unmedicated dysthymic patients with 17 age, sex, and education-matched control subjects in a mood induction paradigm using the International Affective Pictures System (IAPS).
Results
Using a random effects analysis to compare the groups, the results revealed that the dysthymic patients had significantly reduced activation in the dorsolateral prefrontal cortex compared to controls. The dysthymic patients exhibited increased activation in the amygdala, anterior cingulate and insula compared to controls and these differences were more evident when processing negative than positive images.
Limitations
This study included both early and late subtypes of dysthymia, and participants were only imaged at one time point, which may limit the generalizability of the results.
Conclusions
The findings suggest the involvement of the prefrontal cortex, anterior cingulate, amygdala, and insula in the neural circuitry underlying dysthymia. It is suggested that altered activation in some of these neural regions may be a common substrate for depressive disorders in general while others may relate specifically to symptom characteristics and the chronic course of dysthymia. These findings are particularly striking given the history of this deceptively mild disorder which is still confused by some with character pathology.
aUniversity of Toronto, Mood and Anxiety Disorders Program, Centre for Addiction and Mental Health, 250 College Street, Toronto, ON, Canada M5T 1R8
bUniversity of Ottawa, Faculty of Medicine, 451 Smyth Road, Ottawa, ON, Canada K1H 8M5
cDepartment of Diagnostic Imaging, The Ottawa Hospital, 501 Smyth Road, Ottawa, ON, Canada K1H 8L6
dOttawa Health Research Institute, 725 Parkdale Avenue, Ottawa, ON, Canada K1Y 4E9
Corresponding author. University of Toronto, Mood and Anxiety Disorders Program, Centre for Addiction and Mental Health, 250 College Street, Toronto, ON, Canada M5T 1R8. Tel.: +1 416 979 6933; fax: +1 416 260 4171.
ABSTRACT