An update on regional brain volume differences associated with mood disorders.

Area of Science:

• Neuroimaging
• Psychiatry
• Brain Anatomy

Background:

• Magnetic resonance imaging studies reveal structural brain changes in mood disorders, but findings are often inconsistent.
• Previous research has not consistently identified demographic or clinical factors associated with these observed brain volume alterations.

Purpose of the Study:

• To systematically review and identify demographic or clinical characteristics associated with regional brain volume changes in individuals with mood disorders.
• To reconcile divergent findings in neuroimaging studies of major depressive disorder and bipolar disorder.

Main Methods:

• A systematic literature search was conducted on MEDLINE for English-language studies published between January 2004 and July 2005.
• Iterative searching of cited references was performed to identify additional relevant studies.

Main Results:

• Small hippocampal volumes are noted in recurrent major depressive disorder, particularly with childhood onset, but less consistently in early adult-onset depression or bipolar disorder.
• Amygdala volume changes are inconsistently reported in major depressive disorder and bipolar disorder.
• Limited reports exist for frontal cortex and striatal volumes; psychotropic medication effects necessitate treatment history documentation.

Conclusions:

• Patient age, sex, age at onset, illness course, and treatment status are potential factors influencing the detection of regional brain volume changes in mood disorders.
• These variables are critical for interpreting neuroimaging findings and understanding heterogeneity in mood disorder research.