Lithium in the Normal Therapeutic Range: A Potential Sneaky Danger for the Brain. A Case of Slow Tricking Neurotoxicity and a Brief Overview of Literature

In medicine, Lithium salts are known to be useful as a mood-stabilizing drug in the treatment of bipolar disorder and depression. In neurology Lithium is used as prophylaxis of cluster headache. Lithium may induce intoxication with renal failure, thyroid dysfunction, cardiac arrhythmias and neurotoxicity. Toxicity signs are associated with increased serum concentrations (>1.2 mEq/l); however, there have been some reports of neurotoxicity also with therapeutic drug levels. We describe the case of a 70 years old woman who was assuming Lithium for a bipolar disorder with a permanent control of psychiatric symptoms. After 40 years of continued therapy with lithium she developed a rapidly progressive dementia with multifocal brain signs, although lithium serum levels were always normal. She was carefully investigated with regard to the cognitive decline and all possible primary and secondary rapidly progressive dementia were excluded. When the clinical state was quite terminal, all therapies were interrupted and she progressively recovered after withdrawal of lithium therapy.