This interview took place on September 24, 2008, and was conducted by Norman Sussman, MD.
This interview is also available as an audio PsychCastTM at http://psychcast.mblcommunications.com.
Disclosure: Dr. Perkins is a consultant to Dainippon Sumitomo Pharma Co., Ltd; is on the speaker’s bureaus of AstraZeneca and Eli Lilly; and receives grant support from Janssen.
Dr. Perkins is professor of psychiatry in the Department of Psychiatry at the University of North Carolina (UNC) School of Medicine in Chapel Hill. She is medical director of Outreach and Support Intervention Services at UNC Hospitals and the UNC-Chapel Hill School of Medicine. Dr. Perkins’ research emphasizes treatment of the prodromal period and early intervention of the first episode of schizophrenia. Currently investigating pharmacologic and psychotherapeutic treatments for psychosis, she focuses on managing side effects of atypical antipsychotics and the weight gain mechanism in patients taking psychotropic medications. In addition, Dr. Perkins is investigating the genetic basis of schizophrenia.
How has the pathogenesis of schizophrenia evolved in the last century?
It is known that both gene and environment contribute to schizophrenia risk. For example. when an identical twin has schizophrenia, his or her counterpart has a 50% chance of having schizophrenia as well.1 This compares to the population risk of .01%. It is also likely that genetic or environmental risk factors act by changing when and how much protein is made.2
In addition, some forms of schizophrenia are likely neurodevelopmental disorders, meaning that the brains of some people who developed schizophrenia may have developed differently from those unaffected with schizophrenia. It may also be that an environmental event is needed to trigger the disorder in an at-risk person.3 There is also strong evidence that neurocircuits involving the front of the brain, especially the prefrontal cortex, are involved in schizophrenia. Much work needs to be conducted, however, to determine the underlying causes of schizophrenia.
It has been found that schizophrenia is a heterogeneous disorder similar to pneumonia; it is likely that there are hundreds of independent causes to schizophrenia. Such heterogeneity makes it challenging to further decipher the pathogenesis of schizophrenia.
How do parents influence their children having schizophrenia?
One epidemiologic finding is that schizophrenia risk is associated with higher paternal age at the time of conception. We do not know the reason for this association, but I could speculate that perhaps it is because men make sperm throughout their life, and as they age genetic mistakes may accumulate in the germ line, including variations in the number of copies of genomic regions as well as point mutations. New evidence suggests that the genetic risk of schizophrenia may be due to de novo mutations in the patient.4,5 This may explain why approximately 70% of people who develop schizophrenia do not have a relative with the disorder.6
Is there anything specific about viruses implicated in early development that might be associated with schizophrenia?
There is a wealth of epidemiologic research showing increased risk in individuals who had certain prenatal environmental exposures. An example is maternal starvation where the risk of schizophrenia in offspring doubles.7 While data show most people whose mothers starved did not develop schizophrenia, there is still a small group that may have a biologic vulnerability. Some leading hypotheses suggest it is micro nutrium, meaning some critical nutrients (eg, vitamins D or B) were not received in utero. The second epidemiologic observation involves the fetus’ exposure to an infectious disease process in utero. As a result of this exposure, risk of schizophrenia in adulthood increases by 2–3 fold. Research on that relationship has tried to determine whether it is brain infection with the virus or the maternal immune response that affects brain development, increasing later risk of schizophrenia. Numerous animal models point to the immune maternal response. For example, if there is an infection or something provoking the maternal immune response, then antibodies, cytokines, or other aspects of the immune system response cross the placenta, enter the fetus, and affect brain development. Epidemiologic studies also find that maternal exposure to a traumatic event during pregnancy is associated with an increased risk of schizophrenia. One mechanistic theory involves stress hormones affecting brain development in utero, making a person vulnerable to schizophrenia in adulthood.
There have been studies investigating viral exposures in childhood and later risk of schizophrenia. For example, one recent population-based epidemiologic study8 found that childhood cytomegalovirus in the central nervous system was associated with a 16-fold increase in schizophrenia risk.
Is there a connection with gene expression?
One percent of a genome codes for a protein. Until recently, the remaining 99% was considered “junk deoxyribonucleic acid (DNA).” There was no explanation for its function; junk DNA was considered an evolutionary relic. However, in the past 5 years, it has been found that ≥50% of DNA is transcribed into ribonucleic acid (RNA), but this RNA is not translated into protein. Instead, this RNA regulates when and how much of the protein-coding genes are expressed. Numerous post-mortem studies of schizophrenia find altered levels of specific RNAs or proteins, suggesting that some process regulating the expression of a protein is impaired. There is no firm evidence of what regulatory processes might be altered, but research is now focusing on the variety of factors that impact protein expression.
Is there evidence that antipsychotics used earlier are neuroprotective?
Eighty-five percent of patients with schizophrenia will report prodromal symptoms; for example, they may report having weird ideas, illusions, or transient hallucinations (eg, hearing clicking noises, someone calling their name when no one was around). In the prodromal stage of psychosis, people may also complain of increased distractability, problems in school, and social problems. Researchers have been looking at the kinds of symptoms that can help distinguish people at highest increased vulnerability to schizophrenia. The best predictors of psychosis risk appear to be altered thought process (eg, ideas of reference) and abnormal perceptions (eg, illusions or brief hallucinations) that also interfere with social or vocational function.
Current estimates are that approximately 35% to 40% of people experiencing these “clinical high-risk” symptoms will develop a psychotic disorder within 2 years.9 Note that most people who are experiencing these “psychosis-like” symptoms do not go on to develop a psychotic disorder. Some (approximately 20%) will remit; here the symptoms may have been the result of a rough time or a glitch in adolescent brain development that self-corrected. Other times the person was experiencing early symptoms of anxiety disorders, depression, or a personality disorder, but not schizophrenia.
There is great interest in improving the ability to predict risk. One factor that has emerged is functional impairment. The more severe the symptoms, the more they significantly interfere with function. Environmental factors, such as marijuana use or severe stress may further increase psychosis vulnerability. However, more research is required to appropriately identify symptoms before prevention is possible. Studies10-12 examined people experiencing prodromal symptoms who have investigated an antipsychotic, an antipsychotic plus psychotherapy, or psychotherapy alone. In these studies, all interventions were equally successful in preventing psychosis, meaning both pharmacologic and psychotherapeutic interventions could benefit patients.
When the clinician is faced with an adolescent or young adult having clinical high risk symptoms and also struggling in school, treatment decisions are complicated by the fact that most (>50%) will not develop a psychotic illness. While preventative antipsychotic treatment may benefit the approximately 40% who are truly in the earliest stages of illness, antipsychotics are not appropriate for the other 60% of patients. These patients would be unnecessarily exposed to the risks of antipsychotics, such as metabolic or neurologic side effects. In addition, the clinical trials find that patients who are clinically at risk for psychosis are only protected from psychosis while they are taking the antipsychotic. When the antipsychotic is discontinued, the patients continue to be at high risk, and eventually 35% to 40% will develop a psychotic disorder. I think treating clinical high-risk symptoms with an antipsychotic is premature and should only be used when a patient is suffering severe functional impairment. Psychotherapy, however, is a relatively benign and effective treatment. Clinicians should consider some form of psychotherapy, especially a cognitive-behavioral type to help people cope with symptoms, manage stress, and deal with life issues conducive to stress.
Do atypical antipsychotics cause less risk of tardive dyskinesia than the older treatments?
Despite the ongoing debate on this issue, I think they do. In the early part of my career, only typical antipsychotics were available. Tardive dyskinesia was not at all unusual. In my clinical practice tardive dyskinesia is unusual. Many medical or nursing students rotating through inpatient and outpatient settings will not see a single case of tardive dyskinesia.
Studies on tardive dyskinesia risk are difficult to conduct. Unmedicated people with schizophrenia will develop dyskinetic movements that are indistinguishable from tardive dyskinesia. While dyskinetic movements are not necessarily caused by antipsychotics, there is clear evidence showing antipsychotics increase the risk of developing those movements. In order to understand the difference between the two treatments, patients may have to be followed for several years. Unfortunately, studies of that length are almost impossible to conduct. The reinterpretation of short-term clinical studies suggest that tardive dyskinesia happens less often with patients treated with atypical antipsychotics. Tardive dyskinesia can certainly emerge in people treated with atypical antipsychotics, but it appears less likely than in patients treated with typical antipsychotics.
Why do antipsychotics tend to cause weight gain and metabolic syndrome?
These adverse effects are seen mostly with newer antipsychotics. For example, patients taking quetiapine, olanzapine, or risperidone have increased risk of weight gain while aripiprazole or ziprasidone might not cause weight gain (at least in adults). In children, there is some increased risk of weight gain and metabolic syndrome with ziprasidone.
There are three possible mechanisms that could explain weight gain and metabolic syndrome in antipsychotic treatment patients. First, the patient’s appetite might increase once starting the antipsychotic. Second, patients using sedative drugs experience increased sleep time, resulting in a decrease in the amount of calories spent in a 24-hour period. Decreased activity is conducive to weight gain. Third, there may be changes in metabolism—for example, how readily a person may tap into fat stores.
I advise patients to exercise regularly and go on a low carbohydrate diet such as the American Diabetic Association diet or the Atkins diet. I have had patients who were able to follow that kind of diet and lose weight associated with antipsychotics. However, weight loss and behavioral change is a difficult task to accomplish, even for people who have schizophrenia. In addition to lifestyle changes, there is emerging evidence from clinical trials13 that metformin may attenuate or even reverse antipsychotic-related weight gain. In addition, there are clinical trials13 suggesting similar benefits from topirimate and amantadine.
Are there developing treatments that may benefit people who are not being treated effectively?
We are learning more about how to best use available treatments. Most clinical trials with antipsychotics were conducted by pharmaceutical industries. As the studies are highly regulated, the data are valid. However, the problem with industry-sponsored studies is that they are initially designed in favor of the company’s drugs. For example, if there is a drug that could cause weight gain, the researchers might not weigh people in the study. There is a fundamental problem with depending on the people who may profit from the drug conducting all of the studies with that drug.
The Clinical Antipsychotic Trials in Intervention Effectiveness (CATIE) study14 involved the atypical antipsychotics that were FDA approved at the time, namely risperidone, quetiapine, and olanzapine. Ziprasidone was added once it was approved by the Food and Drug Administration. Perphenazine was chosen as a typical antipsychotic comparator because the researchers wanted a drug that was unfamiliar and not used. The outcome measure in the CATIE study was all-cause treatment discontinuation. This was picked because it was thought to reflect both clinicians’ and patients’ judgment on how well a medication was working. If a patient experiences enough benefit from a medication and the side effects are not too troublesome, he or she is willing to continue using it. However, if the benefits seem negligible or the side effects are too much relative to the benefit, the patient will stop taking that medication. This was a novel outcome measure that is still somewhat controversial, but it was chosen as a measure of overall effectiveness. The study was large; it randomized 1,400 patients from the United States. Unlike most pharmaceutical industry studies, the CATIE study did not restrict inclusion to those patients who are very healthy, who do not use street drugs, and/or who do not require treatment with other medications, making the findings generalizable to routine clinical practice.
Overall, the study found that 74% of patients discontinued treatment prior to the end of the 18-month study. The time to discontinuation was significantly longer for olanzapine compared to risperidone and quetiapine, and was longer at a trend level compared to perphenazine- and ziprasidone-treated patients. However, olanzapine-treated patients were more likely to gain weight and have lipid abnormalities, so that the improved effectiveness came at the price of more severe side effects. One of the surprising findings of the CATIE study was how well the typical antipsychotic perphenzine peformed compared to the other antipsychotics, especially since other studies had shown that other typical antipsychotics, like haloperidol and chlorpromazine, were not as efficacious as the atypical antipsychotics. Perphenazine prescribing has increased since the publication of the CATIE study.
What can also be concluded from the CATIE study is that none of the study drugs are optimal, and that treatment discontinuation rates overall are very high. There are now efforts to develop better strategies to improve medication treatment adherence, both with schizophrenia as well as other chronic diseases. Only approximately 50% of patients being treated for chronic illness are compliant with that treatment by 1 year,15 and the reasons for poor adherence are similar in schizophrenia and other chronic disease. We know that there will be a low rate of treatment adherence if a clinician simply writes a prescription and hands that prescription to the patient. A different kind of therapeutic model is needed.
There is growing evidence of a “concordance” model of care, where the patient’s experience of the illness and how treatment affects his or her life is taken into consideration. The clinician may engage in a negotiation with the patient until both agree with the treatment plan. However, it is important to note that even the best-intended patient will likely have difficulties in complying long term. It is difficult to remember to take a medication every day. To be successful, patients usually need to actively work on medication adherence, and the clinician can help. For example, the clinician can keep the medication regimin as simple as possible and also encourage the use of “cognitive adaptive strategies,” where patients develop environmental cues, like pill boxes or alarms to help with adherence.16 The lessons from the CATIE study reveal more than just the need for a new drug. Better ways to use available medication and optimize treatment are needed as well.
There may be breakthrough drugs on the horizon, however. There is a recent clinical trial of a drug that is a selective agonist at certain glutamate receptors (mGluR2 and mGluR3), but that does not affect dopamine receptors. The first published clinical trial17 is promising, and this new drug, at this point called “LY2140023,” may open up a new strategy for treating schizophrenia. Other promising areas include drugs targeting nicotinic receptors. PP
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