Cognitive sequelae of lithium intoxication: a case report

Lithium intoxication is known to induce cognitive deficits along with motor and behavioral changes, even in association with normal serum levels. However, cases with comprehensive neuropsychological assessment of the deficits are rare. In our patient, we initially found severe cognitive deficits, including apraxia and visuo-constructive problems, and temporo-parietal FDG-PET hypometabolism. Neuropsychological and imaging findings were highly suggestive of Alzheimer's disease. However, lithium intoxication was suspected to account for these findings because of a Parkinson's syndrome, despite serum levels being in the upper therapeutic range. This was confirmed as cessation of lithium medication not only let the Parkinson's syndrome disappear, but also lead to dramatic improvements with respect to cognition.