Lithium for prevention of Alzheimer's disease

The Present State of Lithium for the Prevention of Dementia Related to Alzheimer's Dementia in Clinical and Epidemiological Studies: A Critical Review

Despite the unavailability of essential anti-dementia drugs, lithium may inhibit glycogen synthase kinase-3 (GSK-3) and decrease beta-amyloid and hyper-phosphorylated tau. In this review, we hypothesized that trace to standard levels of lithium (i.e., corresponding to the therapeutic levels for bipolar disorder) may be effective for dementia prevention. Excluding three insufficient level studies, we obtained two and one excellent clinical studies on standard and trace lithium levels, respectively, all of which supported the effects of lithium for dementia prevention. In addition, we identified good clinical and epidemiological studies (four each) on standard lithium levels, of which six studies supported the effects of lithium. Moreover, of three good epidemiological studies on trace lithium levels, two supported the aforementioned effects of lithium. The number of studies were substantially small, particularly those on trace lithium levels. Moreover, studies on standard lithium levels were insufficient to establish the efficacy of lithium for dementia prevention. This necessitates accumulating good or excellent clinical evidence for the effects of trace to standard lithium levels on dementia prevention.

L-type calcium channels and psychiatric disorders: A brief review

Emerging evidence from genome-wide association studies (GWAS) support the association of polymorphisms in the alpha 1C subunit of the L-type voltage-gated calcium channel gene (CACNA1C) with bipolar disorder. These studies extend a rich prior literature implicating dysfunction of L-type calcium channels (LTCCs) in the pathophysiology of neuropsychiatric disorders. Moreover, calcium channel blockers reduce Ca(2+) flux by binding to the α1 subunit of the LTCC and are used extensively for treating hypertension, preventing angina, cardiac arrhythmias and stroke. Calcium channel blockers have also been studied clinically in psychiatric conditions such as mood disorders and substance abuse/dependence, yielding conflicting results. In this review, we begin with a summary of LTCC pharmacology. For each category of disorder, this article then provides a review of animal and human data. In particular, we extensively focus on animal models of depression and clinical trials in mood disorders and substance abuse/dependence. Through examining rationale and study design of published clinical trials, we provide some of the possible reasons why we still do not have definitive evidence of efficacy of calcium-channel antagonists for mood disorders. Refinement of genetic results and target phenotypes, enrollment of adequate sample sizes in clinical trials and progress in physiologic and pharmacologic studies to synthesize tissue and isoform specific calcium channel antagonists, are all future challenges of research in this promising field. © 2010 Wiley-Liss, Inc.

Lithium for older adults with bipolar disorder: Should it still be considered a first-line agent?

The use of lithium carbonate for the treatment of bipolar disorder in older adults is decreasing at a significant rate. This change in prescription pattern is occurring at a time when all evidence-based treatment guidelines and systematic reviews still recommend lithium as a first-line treatment for bipolar disorder. Despite having the strongest evidence base for effectiveness, lithium does pose significant concerns in the older population, including the risk of drug interactions that cause toxicity associated with decreased creatinine clearance. The evidence for lithium's impact on chronic renal disease is still controversial and is reviewed in this article. Mixed evidence exists regarding the impact of lithium on suicide risk, although there is a consensus that it does have protective properties through its mood-stabilizing effect. Because of the very limited research base regarding the use of lithium in old age, guidelines for dosing and maintenance of serum concentrations are not well established, and this may be leading to increased episodes of lithium toxicity. At the same time that these legitimate concerns about lithium are being highlighted, evidence has accumulated that suggests that lithium may have neuroprotective properties. Its action of inhibiting the enzyme glycogen synthase kinase-3 may be responsible in part for a decrease in the induction of amyloid beta peptide and hyperphosphorylated tau protein, which have been implicated in the development of Alzheimer's disease. Very little evidence supports use of alternatives to lithium such as other mood-stabilizing agents, including atypical antipsychotics, in older adults. Thus, before we abandon lithium as a first-line agent, we should ensure that the guidelines for lithium treatment are safe, practical and effective. Newer agents must be appropriately tested in older adults before replacing this longstanding first-line treatment for bipolar disorder.

Lithium and neuropsychiatric therapeutics: neuroplasticity via glycogen synthase kinase-3beta, beta-catenin, and neurotrophin cascades

Mood disorders are not merely attributed to the functional defect of neurotransmission, but also are due to the structural impairment of neuroplasticity. Chronic stress decreases neurotrophin levels, precipitating or exacerbating depression; conversely, antidepressants increase expression of various neurotrophins (e.g., brain-derived neurotrophic factor and vascular endothelial growth factor), thereby blocking or reversing structural and functional pathologies via promoting neurogenesis. Since the worldwide approval of lithium therapy in 1970, lithium has been used for its anti-manic, antidepressant, and anti-suicidal effects, yet the therapeutic mechanisms at the cellular level remain not-fully defined. During the last five years, multiple lines of evidence have shown that the mood stabilization and neurogenesis by lithium are due to the lithium-induced inhibition of glycogen synthase kinase-3beta (GSK-3beta), allowing accumulation of beta-catenin and beta-catenin-dependent gene transcriptional events. Altered levels of GSK-3beta and beta-catenin are associated with various neuropsychiatric and neurodegenerative diseases, while various classical neuropsychiatric drugs inhibit GSK-3beta and up-regulate beta-catenin expression. In addition, evidence has emerged that insulin-like growth factor-I enhances antidepression, anti-anxiety, memory, neurogenesis, and angiogenesis; antidepressants up-regulate expression of insulin-like growth factor-I, while insulin-like growth factor-I up-regulates brain-derived neurotrophic factor expression and its receptor TrkB level, as well as brain-derived neurotrophic factor-induced synaptic protein levels. More importantly, physical exercise and healthy diet raise transport of peripheral circulating insulin-like growth factor I into the brain, reinforcing the expression of neurotrophins (e.g., brain-derived neurotrophic factor) and the strength of cell survival signalings (e.g., phosphoinositide 3-kinase / Akt / GSK-3beta pathway). This review will focus on the rapidly advancing new trends in the last five years about lithium, GSK-3beta/beta-catenin, and neurotrophin cascades.