Hippocampal volumes in bipolar disorders: opposing effects of illness burden and lithium treatment

Bipolar Disorders, 05/09/2012

Whereas patients with limited lifetime Li exposure had significantly lower hippocampal volumes than controls, patients with comparable illness burden, but with over two years of Li treatment, or young Li–naive bipolar disorder patients, showed hippocampal volumes comparable to controls. These results provide indirect support for neuroprotective effects of Li and negative effects of illness burden on hippocampal volumes in bipolar disorders.

Methods

  • The authors recruited 17 BD patients from specialized Li clinics, with at least two years of regularly monitored Li treatment (Li group), and compared them to 12 BD participants with < 3 months of lifetime Li exposure and no Li treatment within two years prior to the scanning (non-Li group) and 11 healthy controls.
  • All BD patients had at least 10 years of illness and five episodes.
  • The authors also recruited 13 Li-naïve, young BD participants (15–30 years of age) and 18 sex- and age-matched healthy controls.
  • They compared hippocampal volumes obtained from 1.5-T magnetic resonance imaging (MRI) scans using optimized voxel-based morphometry with small volume correction.

Results

  • The non-Li group had smaller left hippocampal volumes than controls (corrected p < 0.05), with a trend for lower volumes than the Li group (corrected p < 0.1), which did not differ from controls.
  • Young, Li-naive BD patients close to the typical age of onset had comparable hippocampal volumes to controls.

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