No short-term changes of cognitive performance and mood after single doses of two different lithium retard preparations

A Review for Lithium: Pharmacokinetics, Drug Design, and Toxicity

Lithium as a mood stabilizer has been used as the standard pharmacological treatment for Bipolar Disorder (BD) for more than 60 years. Recent studies have also shown that it has the potential for the treatment of many other neurodegenerative disorders, including Alzheimer's, Parkinson's and Huntington's disease, through its neurotrophic, neuroprotective, antioxidant and anti-inflammatory actions. Therefore, exploring its pharmacokinetic features and designing better lithium preparations are becoming important research topics. We reviewed many studies on the pharmacokinetics, drug design and toxicity of lithium based on recent relevant research from PubMed, Web of Science, Elsevier and Springer databases. Keywords used for searching references were lithium, pharmacology, pharmacokinetics, drug design and toxicity. Lithium is rapidly and completely absorbed from the gastrointestinal tract after oral administration. Its level is initially highest in serum and then is evidently redistributed to various tissue compartments. It is not metabolized and over 95% of lithium is excreted unchanged through the kidney, but different lithium preparations may have different pharmacokinetic features. Lithium has a narrow therapeutic window limited by various adverse effects, but some novel drugs of lithium may overcome these problems. Various formulations of lithium have the potential for treating neurodegenerative brain diseases but further study on their pharmacokinetics will be required in order to determine the optimal formulation, dosage and route of administration.

Lithium and cognitive enhancement: leave it or take it?

RATIONALE

Lithium is established as an effective treatment of acute mania, bipolar and unipolar depression and as prophylaxis against bipolar disorder. Accumulating evidence is also delineating a neuroprotective and neurotrophic role for lithium. However, its primary effects on cognitive functioning remain ambiguous.

OBJECTIVES

The aim of this paper is to review and combine the relevant translational studies, focusing on the putative cognitive enhancement properties of lithium, specifically on learning, memory, and attention.

DISCUSSION

These properties are also discussed in reference to research demonstrating a protective action of lithium against cognitive deficits induced by various challenges to the nervous system, such as stress, trauma, neurodegenerative disorders, and psychiatric disorders.

CONCLUSIONS

It is suggested on the basis of the evidence that the cognitive effects of lithium are best expressed and should, therefore, be sought under conditions of functional or biological challenge to the nervous system.

The effects of lithium on cognition: an updated review

RATIONALE

Adverse cognitive effects associated with lithium are often implicated as contributing to vocational and social impairment, as well as medication noncompliance. As impaired cognitive functioning caused by lithium has clear clinical implications, it is important to determine whether evidence for or against impaired cognitive functioning exists in the literature.

OBJECTIVES

An attempt is made to synthesize findings from previous studies, which assess a variety of cognitive domains, to determine whether conclusions can be drawn regarding lithium-associated cognitive impairment. The "reversibility" of neuropsychological impairment following lithium discontinuation and whether lithium administration has negative cumulative effects on cognition were also reviewed.

METHODS

Key word searches on "Medline" and "Psych Info" were completed for clinical articles that investigated the neuropsychological effects of lithium in clinical and normal populations between 1968 and 2000.

RESULTS

Despite methodological flaws, poor replicability and the subtle cognitive effects of lithium, five consistent findings emerged from the review; impairment on tasks of psychomotor speed, impaired functioning in the majority of studies examining verbal memory, no impairment on tasks of visuo-spatial constructional ability or attention/ concentration, and no negative cumulative effect.

CONCLUSIONS

Many patients administered lithium carbonate complained of mental slowness. Lithium carbonate also appeared to have definite, yet subtle, negative effects on psychomotor speed. Studies reviewed also showed a trend toward impaired verbal memory. Recommendations with respect to future research, methodological and statistical problems, and additional clinical implications are presented.

A double-blind, placebo-controlled study of the effects of lithium on cognition in healthy subjects: mild and selective effects on learning

BACKGROUND

Several studies have shown cognitive impairment in short-term memory, long-term memory and psychomotor speed in bipolar patients taking lithium. The aim of the study was to look at the effect of lithium in normal subjects (N=30) taking lithium for 3 weeks. A comprehensive battery was used to assess attention and memory.

METHODS

Subjects were randomized to double-blind treatment with either lithium (N=15) or placebo (N=15) for a 3-week period. Thirteen participants in the lithium group and 15 in the placebo group completed the study. The lithium and placebo were administered twice daily in doses varying from 1050 to 1950 mg (mean=1569 mg). The initial daily dose was calculated according to the Pepin formula to achieve a blood serum lithium level of about 0.8 mmol/l. Cognitive performance (attention, memory) was assessed in each subjects during three periods, i.e. at baseline, after 3 weeks of lithium or placebo, and 2 weeks after discontinuation of study medication.

RESULTS

In short-term memory tasks, the performance of subjects in the lithium group was worst 3 weeks after lithium treatment compared to 2 weeks after discontinuation. In long-term memory, a significantly higher number of words was recalled by the placebo group but not the lithium group.

CONCLUSIONS

Lithium may have an effect on learning when long-term explicit memory test are administered repeatedly. It means that the practice effect when a subject performs the same task several times is less in the lithium-treated group than in the placebo group. This practice effect is related to the learning of a task.