Lithium monotherapy-induced tardive dyskinesia

Area of Science:

• Neuroscience
• Psychiatry
• Pharmacology

Background:

• Tardive dyskinesia (TD) is a neurological disorder associated with long-term use of dopamine receptor blocking agents.
• It is characterized by involuntary, repetitive movements, primarily affecting the face, tongue, and limbs.
• Lithium is a mood stabilizer commonly used for bipolar disorder, generally considered to have a lower risk of TD compared to antipsychotics.

Observation:

• A 68-year-old female with a 15-year history of bipolar disorder on stable lithium monotherapy (600 mg/day, serum levels 0.6) presented with a tardive dyskinesia-like syndrome.
• The patient had a favorable treatment response to lithium but infrequent outpatient clinic visits.
• The onset of movement abnormalities occurred over the preceding few months.

Findings:

• This report details the first known case of tardive dyskinesia associated with long-term, low-dose lithium monotherapy.
• The patient's symptoms suggest a potential link between lithium and the development of TD, even at therapeutic serum levels.
• This challenges the established understanding of TD etiology, which predominantly implicates neuroleptic agents.

Implications:

• Clinicians should consider tardive dyskinesia in patients on long-term lithium therapy, even at low doses.
• Further research is warranted to elucidate the mechanism by which lithium may induce TD.
• This case underscores the importance of ongoing monitoring for movement disorders in patients receiving long-term psychiatric medications.