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.
Methylene blue is a chemical compound that has been used to treat a variety of medical conditions. This drug has some actions that resemble lithium’s: it inhibits guanylate cyclase, which generates second messenger cyclic GMP, and decreases nitric oxide. New evidence shows it may help depression and anxiety in bipolar disorder when added to lamotrigine.
In patients with bipolar disorder who were all treated with lamotrigine, an active 65mg dose of methylene blue three times per day (for a daily total of 195mg) versus 15mg/day (an inactive dose that produces the same side effect of blue urine) was more effective at treating depression and anxiety in a 12-week crossover study. Side effects, in addition to blue urine, included infrequent nausea, diarrhea, headache, and a burning sensation in the urinary tract. Of the 37 randomized study participants, 27 completed both phases of the entire six-month study. Martin Alda, a researcher who presented the double-blind randomized crossover data at the 2014 meeting of the International Society for Bipolar Disorders, indicated that he has also used this preparation clinically with success, although the pharmacy staff who prepared the capsules were not too happy, because everything the drug touches turns blue.
A 2012 study by Kemp et al. in the journal Bipolar Disorders found that lamotrigine added to combination treatment with lithium and valproate was no more effective than placebo in patients with rapid cycling bipolar disorder. Only 14% (19 out of 133) of rapid cycling patients stabilized upon initial treatment with the open combination of lithium and valproate, a startlingly low rate. In the next phase of the study, 49 patients who were not stabilized were given adjunctive treatment with either lamotrigine (n=23) or placebo (n=26) on a double-blind basis, but no significant difference was observed.
Editor’s Note: This study has two pieces of not-so-good news. The first is that it was so difficult to stabilize these patients with rapid cycling bipolar disorder. The second is that the add-on of lamotrigine, which is highly effective in the prevention of depressions in bipolar disorder, was in this case no more effective than placebo.
This study again demonstrates that rapid cycling bipolar disorder is difficult to treat, and even the use of three proven mood stabilizers in combination is not always effective. Many doctors would recommend an atypical antipsychotic as the next clinical option.
A 30-year observational study published by Andrew Leon and colleagues in the American Journal of Psychiatry has found that anticonvulsants used in epilepsy and for bipolar depression (carbamazepine, lamotrigine, and valproate) do not increase suicidal behavior in bipolar patients.
Editor’s Note: The FDA gave a warning in 2009 that these anticonvulsants were associated with suicidal ideation. This was based on studies of a mixed group of psychiatry and neurological patients in acute placebo-controlled studies, where suicidal ideation is typically a reason for exclusion from the study. Leon et al. used more powerful longitudinal methods to compare the risk of suicidal ideation in individuals taking and not taking anticonvulsants and found no such increase in suicidal behavior.
This is like the FDA warning for antidepressants and suicide, which was based on data from placebo-controlled clinical trials in acute depression (where suicidal patients are excluded). When investigators used the same longitudinal methods as Leon et al. in the anticonvulsant study, they found that antidepressants actually reduced suicidal behavior by 30%.
The bottom line is that the use of anticonvulsants for bipolar disorder should not be discouraged based on the FDA warning about suicidal ideation in mixed neurological and psychiatric patients. In bipolar patients, anticonvulsants do not increase the risk of suicidal behaviors, i.e. suicidal acts or completed suicides.
At the 2012 meeting of the American Academy of Child and Adolescent Psychiatry (AACAP), Melissa P. DelBello presented a poster on the design of a maintenance study in bipolar youth to determine characteristics of patients who stabilized on adjunctive lamotrigine. The study included children aged 10 to 17 who had been diagnosed with bipolar disorder. Of a total 244 potential subjects, 160 individuals or 66% stabilized on lamotrigine during the open (not blind) portion of the study. Of these, 143 were randomized to either lamotrigine continuation or placebo.
Seventeen participants did not enter the randomized phase of the study, primarily because of withdrawal of consent, presumably because they were reluctant to be placed in the placebo group. The authors concluded that a study design involving randomization to medication continuation versus withdrawal with placebo substitution could underestimate the true level of treatment response.
However, the high stabilization rate of 66% using adjunctive lamotrigine in the open phase of the study suggests that the drug is effective. Clearly confirmation of this in the double-blind randomized phase is needed to confirm this prediction.
Memantine (Namenda), which is approved by the Federal Drug Administration (FDA) for use in Alzheimer’s Dementia, is increasingly being used for other conditions. Some doctors prescribe memantine for hyperactivity and attention problems in attention deficit hyperactivity disorder (ADHD), for obsessive compulsive disorder (OCD), and most recently as an adjunct to lamotrigine in bipolar depression. We wrote about the findings of Amit Anand et al. on the use of memantine and lamotrigine in January. These findings have just been published in Bipolar Disorders. The study indicates that the combination of lamotrigine with memantine brought about a rapid onset and greater magnitude of antidepressant effects than the combination of lamotrigine and placebo. The initial dose of memantine was 5mg/day, which was increased to 20mg/day during the study.
Editor’s Note: The potential mechanism of this effect makes sense. Lamotrigine decreases release of glutamate, and memantine blocks glutamate’s actions at the NMDA receptor. Thus the two together would more efficiently decrease glutamate’s effects.
It is possible that memantine could be effective without effecting the normal functions of glutamate. The drug blocks NMDA glutamate receptors that are situated away from the synapse, while allowing NMDA glutamate receptors at the synapse to fulfill their normal functions that support learning and memory. The blocking of only those receptors outside the synapse (extra-synaptic) could explain why memantine has relatively few side effects.
In a long-term study of bipolar patients taking lithium published in Bipolar Disorders last year, the addition of lamotrigine (or paroxetine for those who did not respond to lamotrigine) was significantly better than the addition of placebo. Patients taking lamotrigine with lithium averaged 10 months until a recurrence of a depressive or manic episode, while patients taking placebo with lithium averaged 3.5 months until an episode.
In a poster at the 9th International Conference on Bipolar Disorder (ICBD) held in Pittsburgh in 2011, Rahman and colleagues reported that in patients being treated for bipolar disorder, the addition of atypical antipsychotic aripiprazole to maintenance treatment with lamotrigine was more effective than the addition of placebo to the same maintenance treatment with lamotrigine. Improvements in Young Mania Rating Scores (YMRS) with the combination of aripiprazole plus lamotrigine were significantly greater than that of lamotrigine plus placebo.
Editor’s note: These data add to a growing literature that shows that an atypical antipsychotic added to a mood stabilizer is associated with better prophylactic effects than use of the mood stabilizer alone. Previously, most of the studies of this type of combination used lithium or valproate as the mood stabilizer and, to our knowledge, this is the first to demonstrate that long-term prevention with lamotrigine is enhanced by the addition of an atypical antipsychotic.
Many of the atypical antipsychotics are FDA-approved as adjunctive treatments to mood stabilizers in the long-term treatment of bipolar disorder. The controlled clinical trial data that led to this FDA approval support the practice of many clinicians who prescribe combination treatment rather than monotherapy in order to achieve a more rapid onset of anti-manic stabilization and longer-term maintenance effects. The use of aripiprazole and quetiapine as adjuncts to lithium and valproate is particularly common in bipolar disorder since the same atypical antipsychotics are FDA-approved as adjunctive treatments in unipolar depression, and clinicians are familiar with prescribing them to improve ineffective acute antidepressant treatment.
In a double-blind, placebo-controlled trial for patients with bipolar disorder, Martin Alda and colleagues from Dalhousie University in Halifax, Nova Scotia found that the compound methylene blue was an effective augmentation for mood stablizers. Methylene blue inhibits nitric oxide synthetase and guanylate cyclase, the overproduction of which might be associated with neuronal damage. Since bipolar disorder has consistently been associated with neuronal and glial cell dysfunction and loss, methylene blue could be a promising treatment.
Methylene blue turns urine blue, so in place of a placebo the researchers used very low doses (15 mg daily) of methylene blue compared with the active dose of 195 mgs daily.
Thirty-seven patients were enrolled in the randomized 26-week trial, and all patients were treated with lamotrigine as their primary mood stabilizer and with any additional medications they were already taking. Patients entered in a well or euthymic state (n =20), mildly depressed (n=14), or while minimally cycling (n = 3).
Scores on both the Montgomery-Asberg Depression Rating Scale and the Hamilton Rating Scale for Depression improved significantly, with an effect size of 0.47 and 0.42, respectively. Hamilton Anxiety Rating Scale scores also improved significantly with an effect size of 0.46.
Methylene blue was well tolerated, with only transient and mild side effects observed. However, the FDA has issued a warning that using methylene blue with serotonin active agents can lead to a severe serotonin syndrome (because methylene blue is a potent inhibitor of MAO-A and will increase brain serotonin levels when used in conjunction with serotonin active antidepressants). Symptoms of serotonin syndrome can include confusion, hyperactivity, sweating, fever, shivering, diarrhea, trouble with coordination, and even seizures.
The researchers at Dalhousie University concluded that methylene blue used as an adjunctive medication to lamotrigine and other previously inadequately effective agents (only those which are NOT serotonin active) significantly improved depression and anxiety in patients with bipolar disorder. They proposed further exploration of the mechanisms involved in this change, with the possibility that other drugs with similar actions could also be effective in this disorder.
Anil Malhotra from the Zucker Hillside Hospital found that pramipexole (Mirapex), a dopamine D2 and D3 agonist used in the treatment of Parkinson’s disease, improved measures of processing speed and working memory in euthymic bipolar patients (whose average age was 42) when compared with placebo in an adjunctive clinical trial.
Editor’s Note: Bipolar patients in a euthymic phase have consistently been shown to have some degree of cognitive dysfunction that is typically correlated with the number of prior depressive and/or manic episodes they have experienced. This is one of the first studies to directly target this cognitive dysfunction with a pharmacotherapeutic agent.
Pramipexole may be of additional value among depressed patients, because in two small, placebo-controlled studies, one led by Carlos Zarate at the National Institute of Mental Health and one led by Joseph F. Goldberg in New York, pramipexole has been shown to exert acute antidepressant effects in bipolar patients in the depressive phase of the illness. The new data from Malhotra raise the possibility that there could be a two-for-one benefit when pramipexole is used in the depressive phase of bipolar illness—improvement in both depression and cognition.