Telomeres are repeated DNA sequences that sit at the end of chromosomes and protect them during cell replication. Telomeres get shorter with aging and with stressors or psychiatric illnesses. Researcher Alexandre Mathe and colleagues recently found that in a line of rats bred to be more susceptible to stress and depression-like behavior, hippocampal telomeres were shorter than in normal rats or rats bred to be less susceptible. The susceptible rats also had lower levels of enzymes that maintain telomere length. Both telomerase activity and Tert (telomerase reverse transcriptase) expression were reduced in the susceptible rat compared to the other rats. However, lithium reversed the low levels of telomerase activity and Tert expression.
Editor’s Note: Lithium increases hippocampal volume in people, and also increases human telomerase. Researcher Lina Martinsson reported in 2013 that lithium increases telomere length in white cells. Now lithium has increased hippocampal telomerase in a rat model of depression. Short telomeres are associated with aging and increased vulnerability to a wide range of medical and psychiatric disorders. Since people with bipolar disorder are prone to memory problems, medical problems, and short telomeres, they might want to talk to their physician about including lithium in their treatment regimen, if they are not already taking it.
While it can sometimes take weeks for the effects of antidepressant treatments to appear, intravenous ketamine can produce antidepressant effects in as little as two hours. However, ketamine’s effects fade after three to five days. New animal research by Chi-Tso Chiu et al. explores whether adding lithium to ketamine treatment can produce more sustained antidepressant effects.
Mice who are restrained by being placed in a tube for several hours (chronic restraint stress) exhibit a behavioral and neurochemical profile that resembles human depression. When Chiu and colleagues pretreated these stressed mice with sub-therapeutic doses of lithium (600 mg/L) in their drinking water for several weeks, a sub-therapeutic dose of ketamine (2.5 mg/kg of body weight) was enough to produce robust antidepressant effects in the mice, while neither drug alone was effective at these doses.
The combination of ketamine and lithium also restored the density of spines on the dendrites of neurons in the medial prefrontal cortex. Post-treatment with lithium (1200 mg/L) for several weeks was also successful in extending the effects of a single (50 mg/kg) ketamine injection.
Both lithium and ketamine affect the intracellular signaling pathway mTOR. Ketamine activates the pathway, increasing levels of synaptic proteins and dendritic spine density. It also increases brain-derived neurotrophic factor (BDNF) and the BDNF receptor TrkB. BDNF is important for learning and memory.
When lithium was added to the treatment of the mice with ketamine, the mTOR and BNDF pathways were further activated. Lithium also inhibits the receptor GSK-3, supporting ketamine’s rapid-acting antidepressant effects.
Ketamine treatment can produce oxidative stress, in which toxic free radicals can endanger cells, and the addition of low doses of lithium also completely prevented this neurochemical side effect.
Chiu and colleagues hope that the findings of this study in mice can eventually be applied to research in humans in the hopes of finding a clinical option that would sustain the rapid-onset antidepressant effects of ketamine for the long term.
There is a large body of research showing that lithium is better than placebo and a variety of comparison drugs at preventing manic episodes in people with bipolar disorder. It has been less clear whether lithium is as effective in preventing depressions in bipolar patients. In a 2014 meta-analysis in the International Journal of Bipolar Disorders, Emanuel Severus and colleagues confirmed that lithium was more effective than placebo at preventing mood episodes overall and manic episodes. In a fixed effect statistical analysis, lithium was also better at preventing depressive episodes.
The portion of the meta-analysis comparing lithium to placebo included seven randomized controlled trials that included a total of 1,580 patients. Lithium was more likely than placebo to lead to patients dropping out of a study for reasons other than a mood episode, but patients who received lithium were more likely to complete their clinical trials.
Another part of the meta-analysis compared lithium to anticonvulsant drugs. Seven trials were included totaling 1,305 patients. Lithium was better than anticonvulsants at preventing manic episodes, but equally effective at preventing mood episodes overall and depressive episodes specifically. There was also no difference in patients dropping out of the trials or completing the trials.
The researchers concluded that lithium remains the most valuable treatment option for bipolar disorder, because no other drug has such consistent efficacy in preventing manias and depressions and mood episodes in general.
At the 2014 meeting of the American Academy of Child and Adolescent Psychiatry, researcher Adelaine Robb reported that in 81 children with mania (aged 7-17), lithium was superior to placebo in reducing the severity of mania measured on the Young Mania Rating Scale. There had been some debate about the efficacy of lithium in young children with mania, but this study clearly indicates lithium’s effectiveness. The drug is approved by the Federal Drug Administration (FDA) for use in patients with bipolar disorder aged 12 and up.
Another researcher, Vivian Kafrantaris, found that in children who averaged 14.5 years of age, lithium increased the volume of the corpus callosum, a bundle of neural fibers that connects the brain’s right and left hemispheres. Lithium also normalized white matter integrity in other neural fiber tracts—the cingulum bundle and the superior longitudinal fasciculus. The authors concluded that lithium may “facilitate microstructural remodeling of white matter tracts involved in emotional regulation.”
Editor’s Note: There is much research showing that in adults, lithium has positive effects on the brain, including increases in hippocampal and cortical grey matter volume. Now it appears that lithium can improve white matter integrity in the developing brain as well.
Lithium Plus An Atypical Antipsychotic Was More Effective Than Valproate Plus An Atypical Antipsychotic In One Study, But Not Another
Evaristo Nieto et al. of Spain presented a poster about the naturalistic study of the efficacy of acute treatment of manic inpatients with lithium and valproate at the 2014 meeting of the International College of Neuropsychopharmacology. In the lithium group, all patients were treated with lithium and oral antipsychotics (N=85). In the valproate group, all were treated with valproate and oral antipsychotics (N=92). Outcome was measured using scores on scales for mania and for general functioning (the YMRS and the CGI-S). The atypical antipsychotic was typically olanzepine or risperidone.
Nieto et al. found that the mean change in CGI scores from baseline to the day of discharge was significantly higher in the lithium group (-2.84 versus -2.6), and concluded that, “Although it is used in more severe cases, treatment of manic inpatients with lithium associated with antipsychotics is more effective than treatment with valproate associated with antipsychotics.”
However, W.M. Bank et al. came to the opposite conclusion in a Korean study. Bank et al. “compared the 1-year rehospitalization rates of first-episode bipolar manic patients?who were discharged while being treated with lithium or valproate in combination with an?atypical antipsychotic….The rehospitalization rate was 17.3% during the 1-year follow-up period.”
Bank et al. found significantly higher rates of rehospitalization in the lithium (23.1%) compared to the?valproate (13.3%) group using the Kaplan-Meier formula for estimations.
In a recent study comparing the efficacy of lithium and the second-generation antipsychotic quetiapine, the drugs had remarkably similar results. Researcher Andrew Nierenberg et al. presented the results at the 2014 meeting of the American Society of Clinical Psychopharmacology. In the 6-month study called CHOICE (Clinical Health Outcome Initiative Comparative Effectiveness), 482 patients received either lithium or quetiapine in addition to other medications in a manner consistent with clinical practice. For the purposes of the study, those receiving lithium could not receive quetiapine or another antipsychotic, and those receiving quetiapine could not receive lithium or another antipsychotic, but both groups could receive other types of adjunctive medications.
By the end of the 6-month study period, most patients had improved substantially, but only about a quarter of each group became truly well. The researchers suggest that patients may need a longer period of treatment or other interventions such as psychotherapy or combination treatment. Clinicians were told to use the maximum dose of lithium or quetiapine that each patient could tolerate. Mean maximum doses were 1007.5mg of lithium and 344.9mg of quetiapine.
One surprise for the researchers was that 24% of lithium patients and 27% of quetiapine patients required no other medications and improved on monotherapy.
While results were very similar for two drugs, lithium produced slightly greater side effects and produced slightly better results in patients with anxiety. This may have been due to those patients also receiving benzodiazepines, and the researchers are analyzing data to see whether the patients with anxiety did indeed receive this kind of adjunctive treatment. Quetiapine was slightly better in patients who had more manic symptoms.
In another surprise finding, patients with bipolar II disorder fared better overall than patients with bipolar I disorder. Patients with higher suicide risk did worse than those with lower suicide risk.
In a special symposium on bipolar disorder at the 2014 meeting of the American Psychiatric Association, researcher Mike Bauer reviewed a new meta-analysis that showed lithium not only has significant effects in preventing manias, but also depressions. Researcher Geddes et al. had, in a previous study called BALANCE, found that lithium was superior to valproate (Depakote). Together these findings led Bauer to the conclusion that lithium is under-used in the treatment of bipolar disorder, especially in the US, where lithium is prescribed less often than valproate.
An article by researcher Kessing in the British Journal of Psychiatry in 2012 relied on naturalistic follow up data and also showed that lithium was superior to valproate in preventing hospitalizations.
A study by researcher Willem Nolen indicated that in mono-therapy, levels of lithium in the blood needed to be 0.6 meq/L or higher in order for lithium to work better than placebo. Lithium augmentation that produced lower blood levels of 0.3 meq/L was not significant on its main outcome measure of preventing new episodes. However, compared to treatment as usual, those randomized to lithium used lower doses of atypical antipsychotics, and other data indicated that these patients had fewer suicide attempts and increased hippocampal volume.
Bauer noted that lithium-related goiter and low thyroid are easily treated, and that kidney damage while taking lithium can be prevented by avoiding episodes of lithium intoxication. It is easy to conclude that lithium should be used more often, especially given its positive effects against suicide and brain gray matter and hippocampal volume loss.
Lithium is known for protecting neurons by inducing neurotrophic factors and inhibiting cell death factors. In a new study, other mood-stabilizing drugs had similar neuroprotective and neurotrophic effects on cultured neurons from the hippocampus.
At the 2014 meeting of the International Society for Bipolar Disorders, CH Lee et al. presented evidence that lithium, carbamazepine, valproic acid, and lamotrigine all increase the outgrowth of dendrites from these cultured neurons. Therapeutic levels of these drugs increased the production of proteins like brain-derived neurotrophic factor (BDNF), postsynaptic density protein-95 (PSD-95), neurolignin 1 (NLG 1), beta-neurexin, and synaptophysin. However, so far only lithium has been shown to increase the volume of the human hippocampus as measured with MRI.
A 2004 meta-analysis of previous research showed that lithium was better than placebo at preventing affective episodes and preventing manic episodes. The evidence for the drug’s efficacy in preventing depression was less clear. A new meta-analysis by E. Severus et al. (not yet published) confirms the previous findings and provides new evidence that lithium is also better than placebo at preventing depressions.
The study also suggested that lithium is better than anticonvulsant mood stabilizers at preventing relapse and recurrence, but this finding only reached statistical significance in the prevention of new manic and hypomanic episodes.
Editor’s Note: These findings highlight the desirability of greater lithium use. The drug is currently prescribed less often in the US than it is in Europe. In addition to lithium’s efficacy in the long-term preventative treatment of bipolar disorder, there is evidence that lithium is also the best agent for suicide prevention and for neuroprotective effects.
Suicide is a serious risk for people with mood disorders. We have noted before that various studies of lithium show that the drug lowers suicide risk in people with mood disorders. A 2013 meta-analysis by Andrea Cipriani et al. in the journal BMJ confirms this finding. The review of 48 randomized controlled trials comparing lithium with placebo or other active drugs in the long-term treatment of mood disorders showed that lithium reduces the risk of suicide and death from any cause.
Lithium was more effective than placebo at reducing number of suicides and deaths from any cause, and more effective than carbamazepine and anticonvulsants in general at reducing deliberate self-harm. The authors wrote that lithium seems to reduce risk of suicide and death by more than 60% compared to placebo.
Lithium may reduce suicide risk by preventing relapse of mood disorders, but it may also have other mechanisms of action, such as decreasing aggression or impulsivity.
One thing to note about these findings is that the reduction in suicide risk also applies to those with unipolar depression, not just those with bipolar disorder. There is a case to be made that lithium treatment could be targeted specifically to reduce suicide risk.