Cortical thickness and emotion processing in young adults with mild to moderate depression: a preliminary study.

BACKGROUND: Major depressive disorder (MDD) is a multifaceted illness involving cognitive, emotional, and structural brain changes; illness onset typically occurs in adolescence or young adulthood. Cortical thickness modulations may underlie, or accompany, functional brain activity changes in the prefrontal cortex (PFC) during emotional processing that tend to be observed in MDD. METHODS: Thirteen unmedicated young adults with mild to moderate MDD, aged 18-24, completed a facial expression Go/No Go task and underwent a magnetic resonance imaging (MRI) scan to assess cortical thickness. Cortical thickness and performance on the Go/No Go task was also assessed in age-matched healthy comparison subjects (HCs; N = 14). RESULTS: Participants with depression had thicker left pars opercularis cortices than HCs. They also exhibited impaired response inhibition to neutral faces when responding only to sad faces, and a faster response time overall. CONCLUSIONS: Though our sample size is limited, this pilot study nevertheless provides evidence for cortical thickening in left frontal brain regions in a non-severely depressed, young adult group compared to healthy controls. There was also evidence of disturbances in emotion processing in this group.

Influence of age of onset on limbic and paralimbic structures in depression.

AIM: Major depressive disorder (MDD) onset during childhood/adolescence is associated with a greater illness burden and distinct clinical profile. However, limited research exists on the effect of age of MDD onset on volumetric abnormalities in para/limbic structures during adulthood. METHODS: Subgenual anterior cingulate cortex (sgACC), hippocampus and caudate nucleus volumes were measured by manual tracing in depressed individuals (n = 45) and healthy controls (HC; n = 19). Volumetric comparisons were carried out between HC and MDD patients divided into those with pediatric (≤ 18 years; n = 17) and adult onset (≥ 19 years; n = 28). RESULTS: The adult MDD-onset group had smaller sgACC volumes than the pediatric-onset and HC groups (age, sex controlled). No differences in caudate and hippocampus volumes existed. sgACC and hippocampal volumes were inversely correlated with depression severity. CONCLUSIONS: Surprisingly, pediatric MDD-onset was not associated with more pronounced sgACC, hippocampus and caudate volume reductions. Nevertheless, age of illness onset appears to be a meaningful dimension of study in efforts to understand the neurobiological heterogeneity of MDD.

Aerobic exercise in depressed youth: A feasibility and clinical outcomes pilot.

AIM: Major depressive disorder (MDD) onset generally occurs in adolescence/early adulthood. However, pharmacotherapy use in younger populations is restricted due to black box warnings. Aerobic exercise may be a viable treatment option for mild-to-moderate MDD, but little is known about its acceptability/effectiveness in young adults. METHODS: Unmedicated and relatively inactive 18-to-24 olds with MDD completed fitness/clinical assessments at baseline and after 12 weeks of supervised aerobic exercise (3×/wk; 30-minute sessions in target heart rate [HR] zone), with the aim of increasing cardiovascular fitness (VO2max -indexed). RESULTS: Post-intervention, predicted VO2max increased, whereas depression scores decreased. A correlation existed between time spent in target HR zone and anxiety symptom decreases. Exercise adherence and satisfaction were high, and drop-out was minimal. CONCLUSIONS: This pilot is among the first to assess the feasibility of aerobic exercise as an antidepressant treatment strategy in young adults, a group for which options have limited acceptability.

Subgenual anterior cingulate cortex and hippocampal volumes in depressed youth: The role of comorbidity and age.

OBJECTIVES: Many studies have reported that adults with recurrent major depressive disorder (MDD) have smaller hippocampal volumes than control participants. The data are more variable in youth with MDD, where findings have been inconsistent and the effects of factors such as age and co-morbidity have not been systematically examined. This study therefore assessed hippocampus and subgenual anterior cingulate (sgACC) morphometry in 168 youth, aged 12-25, with or without MDD and comorbid anxiety. METHODS: Structural magnetic resonance imaging (MRI) scans and clinical assessments were obtained from 80 participants with MDD (36 with comorbid anxiety disorder) and 88 age-matched control participants. RESULTS: Participants with MDD had smaller right hippocampi than controls (p=.013). Older depressed participants (20.1-25 years) had smaller hippocampal volumes than younger ones (<20.1 years; p=.05); this age effect was not apparent in controls (p=.46). Depression scores, indexed by the HAMD17, correlated with hippocampal volumes in older depressed youth. Depressed participants with comorbid anxiety had smaller sgACC, but not hippocampal, volumes than those without anxiety (p=.042). LIMITATIONS: Longitudinal, versus cross-sectional, studies can most optimally assess the influence of depression on neurodevelopmental profiles. Though our participants were largely treatment-naïve or in their first week of pharmacotherapy, a handful had extensive treatment histories; thus, treatment history may have influenced brain morphometry. CONCLUSIONS: Age effects were apparent when hippocampal volumes of older and younger participants with MDD were compared; such differences were not apparent in healthy participants. Comorbid anxiety was associated with decreased sgACC volumes suggesting delayed or altered neurodevelopment in a key emotion regulation region.

Age of onset and corpus callosal morphology in major depression.

BACKGROUND: The corpus callosum and related white matter projections have been implicated in major depressive disorder (MDD). Previously, we found a smaller genu in adolescents with MDD as compared to controls. To date, no study has examined the age of depression onset (adult vs. pediatric) as it relates to genu area in adults with MDD. METHODS: The area of the corpus callosum and its sub-regions were measured in 21 MDD subjects with pediatric age of onset (≤18 years) (29.48±7.62 years; 16 female, 5 male) and 31 MDD subjects with adult age of onset (≥19 years) (41.42±8.85; 17 female, 14 male) and 19 healthy controls (32.89± years 9.98; 11 female, 8 male) using magnetic resonance imaging (MRI). RESULTS: A difference in genu area was noted between groups (p=0.03), after co varying for age with post-hoc tests revealing that the difference was driven by the subjects with an MDD onset of pediatric age (p=0.035). No other sub-regions or total corpus callosum area demonstrated a significant difference. Genu area correlated with age in controls (p=0.02) but not in MDD patients (p=0.35). No significant correlation was found between the confound illness duration and genu area in MDD subjects with pediatric age of onset. LIMITATIONS: Confirmation and extension of our findings requires a larger sample size and usage of diffusion tensor imaging. CONCLUSIONS: Our findings provide additional evidence of abnormalities in the genu of the corpus callosum in early onset depression that persist into adulthood.