Marijuana Addiction Associated with White Matter Loss and Brain Changes in Healthy People and Those with Schizophrenia
It has been established that cannabis use is associated with impairments in working memory, but researchers are still investigating how these impairments come about. A 2013 study by Matthew J. Smith et al. in the journal Schizophrenia Bulletin compared regular marijuana users both with and without schizophrenia with demographically similar people who did not use marijuana.
Using magnetic resonance imaging (MRI), the researchers were able to map each participant’s brain structures. Healthy people who were marijuana users showed deficits in white matter (axons of neurons that are wrapped in myelin) compared to healthy people who did not use the drug. Similarly, patients with schizophrenia who used marijuana regularly had less white matter than those patients with schizophrenia who did not use the drug. There were also differences in the shapes of brain structures, including the striatum, the globus pallidus, and the thalamus, between cannabis users and non-users.
Differences in the thalamus and striatum were linked to white matter deficits and to younger age of cannabis use disorder onset.
Differences between cannabis users and non-users were more dramatic across the populations with schizophrenia than across the healthy populations.
Editors note: Future research is needed to determine whether marijuana causes these brain changes, or whether the brain changes are a biomarker that shows a vulnerability to marijuana addiction (although the latter is less likely than the former).
Other data show that marijuana is associated with an increase in psychosis (with heavy use), cognitive deficits, and an earlier onset of both bipolar disorder and schizophrenia in users compared to non-users. These findings make pot begin to look like a real health hazard. With legalization of marijuana occurring in many states, ease of access will increase, possibly accompanied by more heavy use. The most consistent pharmacological effect of marijuana is to produce an amotivational syndrome, characterized by apathy or lack of interest in social activities. Particularly for those already struggling with depression, pot is not as benign a substance as it is often thought to be.
Tardive dyskinesia is a sometimes irreversible side effect of antipsychotic treatment, and is characterized by uncontrollable, subtle and spontaneous motor movements, usually of the tongue, mouth, or fingers.
Extracts of the leaves of the gingko biloba tree contain potent antioxidants. In a study published by Zhang et al. in the journal Biological Psychiatry in 2012, treatment with ginkgo biloba (EGb-761) at 240mg/day for 12 weeks improved tardive dyskinesia more than placebo. Patients with tardive dyskinesia had low levels of brain-derived neurotrophic factor (BDNF) at baseline, and gingko biloba increased these levels. BDNF is important for the production and protection of neurons, and maintaining long-term memory.
The increase in BDNF was correlated with the degree of improvement achieved with gingko biloba in these patients. Different people have different variations in the gene for BDNF. As a result, some people’s BDNF is transported to dendrites and synapses more efficiently than others’. Improvement was greatest in those patients with the most common and best-functioning variant of BDNF, Val66Val, and worst in those patients with the rare and poorest-functioning variant, Met66Met.
Editor’s Note: These findings could be of great clinical importance. Tardive dyskinesia occurred in 20 to 40% of patients with bipolar disorder following treatment with the older “typical” antipsychotics. The incidence is much lower with the newer “atypical” antipsychotics, but having an effective and well-tolerated treatment for this disfiguring side effect is an extra bonus.
Metformin Effective for Treating Antipsychotic-Induced Amenorrhea, Weight Gain, and Insulin Resistance in Women
Treatment with antipsychotics often has side effects such as amenorrhea (loss of the menstrual period) and weight gain that make sticking to a treatment regimen difficult for some patients. A 2012 study by Wu et al. in the American Journal of Psychiatry suggests that the drug metformin, often used to treat diabetes, can reverse these changes. The 84 female patients recruited for the study were being treated for a first episode schizophrenia, were on one antipsychotic, and had experienced amenorrhea for several months. They received either placebo or 1000mg/day of metformin in addition to their antipsychotic treatment for six months. Seventy-six women completed the trial.
Metformin was able to reverse the side effects in many of the women. Menstruation returned in 28 of the patients taking metformin compared to only two patients taking placebo. Among those on metformin, body mass index (BMI) decreased by a mean of 0.93, compared to a mean increase in those on placebo (0.85). Insulin resistance improved in the women on metformin as well.
Editor’s Note: Metformin can also delay the onset of type II diabetes in those in the borderline diabetic range. The weight loss on metformin was not spectacular and other options include the combination of the antidepressant bupropion (Wellbutrin) and the opiate antagonist naltrexone (Revia, 50mg/day), monotherapy with topiramate (Topamax), the fixed combination of topiramate and phentermine (Qsymia), or monotherapy with zonisamide (Zonegran).
Repetitive transcranial magnetic stimulation (rTMS) may improve working memory in patients with schizophrenia, according to a small study published by Zafiris J. Daskalakis and colleagues in Biological Psychiatry in 2013. Patients with schizophrenia received either 20 Hz rTMS over the left and right prefrontal cortex or a sham treatment, and the rTMS improved working memory on a particular task, the n-back task, wherein patients are asked to recall whether a stimulus they’re currently viewing is the same as the previous one they viewed, or one they viewed several times back. Twenty sessions of rTMS over a period of 4 weeks brought memory back to the levels seen in normal controls.
Editor’s Note: Since many patients with bipolar disorder also have deficits in prefrontal-based memory and performance even when euthymic, it will be important to see if rTMS would also be helpful in these patients. RTMS at 20 Hz increases neuronal activity as measured by PET scan of the prefrontal cortex and other regions of the brain, and this lasts for at least 48 hours after each treatment.
Since many patients with schizophrenia and bipolar disorder show deficits in prefrontal activity at baseline, the normalization of these alterations could relate to the memory improvement. This proposition could be tested relatively easily.
Researcher Josh Woolley and colleagues at the University of California, San Francisco have found that intranasal oxytocin (at doses of 40 IU) improved social cognition in patients with schizophrenia when compared with placebo. Oxytocin is a hormone that facilitates social bonding. Social cognition refers to the way we understand what emotions other people are communicating through facial expression, voice, etc.
Interestingly, less complicated aspects of social cognition like recognizing affect and distinguishing between sincerity and sarcasm were not affected by the oxytocin treatment. However, more complex types of social inference (such as decoding whether an actor intended sarcasm versus telling a white lie) were substantially improved. These tasks evaluate “theory of mind”—the ability to attribute mental states to oneself and others, and to recognize that another person’s mental state may be different from one’s own. These abilities are sometimes lacking in those with schizophrenia and other disorders, such as autism. Given that these abilities have been related to real world social functioning, Woolley and colleagues suggest that oxytocin could, for example, help these individuals to make more friends.
Many patients with schizophrenia do not reach full remission on antipsychotic drugs alone. The anticonvulsant drug topiramate (Topamax) has shown some promise as an adjunctive treatment for schizophrenia. To clarify the results of studies of topiramate, researcher Christoph Correll and colleagues performed a meta-analysis of nine randomized, placebo-controlled clinical trials of the drug. They found that when topiramate was added to antipsychotic treatment, it improved both positive and negative symptoms of schizophrenia, and it also led to reduced weight.
Editor’s Note: Topiramate might also be useful for patients with schizophrenia who have the common comorbidities of alcohol and cocaine abuse, since in other studies of patients with these primary disorders, topiramate was helpful.
Most drugs used to treat schizophrenia target dopamine and serotonin receptors in the brain. While these are effective in many patients, relapse is common and side effects can be severe. Researchers are looking for ways to target other mechanisms that cause schizophrenia, and inflammation seems to be one of these. There is evidence that a treatment as simple as aspirin, when added to regular treatment with antipsychotics, can improve schizophrenia by targeting inflammation.
In a 2010 study by Laan et al. published in the Journal of Clinical Psychiatry, patients with moderate or severe schizophrenia were given either placebo or aspirin (acetylsalicylic acid, 1000mg) in addition to their regular treatments every day for three months. The patients who received aspirin showed a significant reduction in the positive symptoms of schizophrenia, and to a lesser extent the negative symptoms, compared to those who received placebo. Cognitive function was not improved. The effect size (Cohen d) for the total scale score was 0.5, which is considered a “medium” effect and one that is clinically relevant.
The reductions in symptoms were greater in those patients who had more altered immune function.
Choline Treatment For Pregnant Mothers And Newborns Improves Babies’ Cognition and Normalizes a Risk Factor for Schizophrenia
Deficiencies in GABA inhibition have been linked to the risk of schizophrenia (and perhaps bipolar disorder). GABA receptors are initially excitatory but switch to being inhibitory early in life. Choline derived from phosphatidylcholine or from eggs and meat in the diet is important in increasing GABA receptor development and maturity.
Ross et al. reported this year in the American Journal of Psychiatry that in a placebo-controlled study in which mothers took phosphatidylcholine in the last 2 trimesters of pregnancy (at doses of 3,600mg in the morning plus 2,700mg in the evening) and infants took 100mg/day for 12 weeks, the infants who received choline showed better neuronal inhibition than infants who did not receive choline on a P50 test of auditory evoked potential, in which the brain’s response to a series of beeps is recorded. An overactive P50 response is a sign of deficiencies in GABA inhibition.
In infants with a common gene variant in the alpha 7 nicotinic receptor that makes it function less well (which also may be a risk factor for the development of schizophrenia), the choline regimen normalized the P50 test, while placebo had no effect. However, in a recent study by Cabranes et al. published in Psychiatry Research, there was no association of the alpha 7 gene variant and schizophrenia or bipolar disorder, although patients with bipolar disorder and patients with schizophrenia did perform differently on the P50 evoked potential test than controls did.
Editor’s Note: In an editorial by Judy Rapoport that accompanied the Ross et al. study, the difficulty of using the findings in clinical practice are discussed. Meck et al. showed in 1999 that choline supplementation enhanced spatial memory, and in several cases nutritional supplements can have beneficial effects on the brain. Rapoport notes the success of perinatal folate in preventing neural tube defects and the likelihood that Vitamin D supplementation can prevent some cases of schizophrenia.
However, extrapolating the choline findings of Ross et al. to clinical practice, especially given the lack of association of the alpha 7 gene variation to psychiatric illness in the study by Cabranes et al., might be premature. Instead, Rapoport recommends a good diet and prevention of infection as first steps for treatment. Choline supplementation would be roughly equivalent to three eggs a day.
According to a large family study of people with severe mental disorders that was published by Kyaga et al. in the British Journal of Psychiatry last year, people with bipolar disorder and siblings of people with schizophrenia or bipolar disorder were much more likely to be working in creative professions than people without severe mental illness.
Kyaga talked to Medscape Medical News about the study:
“I think the study stresses the importance of treating all patients individually, and with the aim of finding the optimal treatment with regards to effectiveness, while minimizing the adverse effects that medication can have on positive aspects of psychiatric disorders,” Dr. Kyaga said.
“We often encounter the suggestion that lithium reduces creativity in patients with bipolar disorder and that adherence therefore is difficult. Now we can say that it is true that bipolar disorder is in fact associated with increased creativity, but we also know from previous research that terminating treatment with lithium in bipolar disorder will, in the long run, disrupt creative behavior,” he continued.
“We therefore need to pay close attention to what patients tell us while being treated, so that we can find a regimen that will work for them to prevent the disastrous consequences of severe psychiatric disorder, while providing them opportunities to uphold their creative behaviors in the long run,” Dr. Kyaga said.
An article by Laan et al. published in the Journal of Clinical Psychiatry in 2010 suggested that aspirin may reduce symptoms of schizophrenia spetrum disorders in patients being treated with antipsychotics.