Brain lithium, N-acetyl aspartate and myo-inositol levels in older adults with bipolar disorder treated with lithium: a lithium-7 and proton magnetic resonance spectroscopy study.
OBJECTIVE
We investigated the relationship between brain lithium levels and the metabolites N-acetyl aspartate (NAA) and myo-inositol (myo-Ino) in the anterior cingulate cortex of a group of older adults with bipolar disorder (BD).


METHODS
This cross-sectional assessment included nine subjects (six males and three females) with bipolar I disorder and currently treated with lithium, who were examined at McLean Hospital's Geriatric Psychiatry Research Program and Brain Imaging Center. The subjects' ages ranged from 56 to 85 years (66.0 +/- 9.7 years) and all subjects had measurements of serum and brain lithium levels. Brain lithium levels were assessed using lithium magnetic resonance spectroscopy. All subjects also had proton magnetic resonance spectroscopy to obtain measurements of NAA and myo-Ino.


RESULTS
Brain lithium levels were associated with higher NAA levels [df = (1, 8), Beta = 12.53, t = 4.09, p < 0.005] and higher myo-Ino levels [df = (1, 7), F = 16.81, p < 0.006]. There were no significant effects of serum lithium levels on any of the metabolites.


CONCLUSIONS
Our findings of a relationship between higher brain lithium levels and elevated NAA levels in older adult subjects with BD may support previous evidence of lithium's neuroprotective, neurotrophic, and mitochondrial function-enhancing effects. Elevated myo-Ino related to elevated brain lithium levels may reflect increased inositol monophosphatase (IMPase) activity, which would lead to an increase in myo-Ino levels. This is the first study to demonstrate alterations in NAA and myo-Ino in a sample of older adults with BD treated with lithium.
Forester
Brent P
BP
Geriatric Psychiatry Research Program, McLean Hospital, Belmont, MA 02478, USA. bforester@mclean.harvard.edu
Finn
Chelsea T
CT
Berlow
Yosef A
YA
Wardrop
Megan
M
Renshaw
Perry F
PF
Moore
Constance M
CM
D000368:Aged; D000369:Aged, 80 and over; D018692:Antimanic Agents / Q000378:metabolism* / Q000627:therapeutic use*; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D001714:Bipolar Disorder / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007294:Inositol / Q000378:metabolism*; D016014:Linear Models; D016651:Lithium Carbonate / Q000378:metabolism* / Q000627:therapeutic use*; D008279:Magnetic Resonance Imaging / Q000379:methods; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D008875:Middle Aged; D011522:Protons
D018692:Antimanic Agents; D011522:Protons; D016651:Lithium Carbonate; D001224:Aspartic Acid; D007294:Inositol; C000179:N-acetylaspartate