Stress is a risk factor for depression and other mental health disorders. Researchers are currently working to clarify how stress leads to depression, anxiety, and post-traumatic stress disorder, and why trauma early in life has lasting consequences.
Two recent studies in mice examined whether just witnessing a stressful event leads to depression-like behaviors. In one, adult female mice watched a male mouse as it was repeatedly attacked by a larger mouse. After ten days of this, the female mice were socially withdrawn, had lost interest in drinking sucrose, and gave up more easily during a physical challenge. They also lost weight and showed higher levels of the stress hormone corticosterone in their blood. The researchers, led by Sergio Iniguez, believe their study clarifies how witnessing traumatic events can lead to stress-induced mood disorders.
In the other study, by Carlos Bolanos-Guzman, adolescent male mice witnessed another mouse being attacked. Both the mice that went through the physical stress of being attacked and the mice that went through the emotional stress of watching the attacks occur showed similar depressive behaviors to the mice in the previous study—social withdrawal, loss of interest in sucrose, decreased food intake and exploration of the environment, and decreased motivation in physical challenges. These behaviors persisted into adulthood. Both groups of mice also had increased levels of corticosterone and reduced expression of a particular protein in the ventral tegmental area, a part of the brain linked to stress response. Bolanos-Guzman suggests that both physical and emotional stress have lifelong consequences in mice.
The studies were presented at a scientific meeting in December.
Many psychiatric illnesses, including bipolar disorder, schizophrenia, autism, attention deficit hyperactivity disorder (ADHD), and anxiety disorders may stem from abnormalities in brain development that begin before birth. Researchers are trying to determine whether dietary supplements taken by pregnant mothers or infants can reduce the risk of such illnesses. At a recent scientific meeting, researcher Randal Ross and colleagues reported that compared to placebo, choline supplements reduced problems with a brain process called sensory gating in one-month-old infants and also improved the children’s attention span and social skills at age 3.
Sensory gating is the process by which the brain filters out unimportant information, to avoid flooding higher cortical centers with irrelevant stimuli. Deficits in the way the brain inhibits response to this type of irrelevant information are associated with mental illnesses such as schizophrenia.
In Ross’s study, healthy pregnant mothers received either a placebo or 6300 mg of choline, a nutrient found in liver, egg yolks, and meat. After delivery, the infants also received 700 mg of supplemental choline per day. In children who carried CHRNA7, a risk gene for schizophrenia discovered by Ross’s colleague Robert Freedman, choline reversed the associated risk of sensory gating problems and normalized their behavior at age 3.
Researchers are looking for better ways of predicting whether children at risk for bipolar disorder will go on to develop the illness. A 2015 study by David Axelson and colleagues in the American Journal of Psychiatry reported that in the offspring of parents with bipolar disorder, diagnoses of sub-threshold mania, depression, and disruptive behavior disorders were associated with subsequent diagnosis of full-blown Bipolar I or Bipolar II disorders six to seven years later.
More recently, in an article by Danella M. Hafeman and colleagues in the American Journal of Psychiatry, the same group of investigators has examined how symptoms (rather than categorical diagnoses, as in the earlier study) predict the development of bipolar disorder. In children and adolescents at high risk for bipolar disorder (because they have a parent with the disorder) three types of symptoms were the best predictors of later bipolar disorder: anxiety/depression at the time participants entered the study, unstable mood or irritability both when entering the study and shortly before a bipolar diagnosis, and low-level manic symptoms observed shortly before diagnosis.
The earlier the age at which a parent was diagnosed with a mood disorder, the greater the risk that the offspring would also be diagnosed with bipolar disorder. Youth with all four risk factors (anxiety or depression, mood changes, low-level mania, and a parent who was diagnosed with a mood disorder at an early age) had a 49 percent chance of developing bipolar disorder, compared to a 2 percent chance among those without those risk factors.
Childhood onset of bipolar disorder and long delays until first treatment for depression or mania are both significant predictors of a poor outcome in adulthood compared to adult onsets and shorter delays to treatment. Read more
A recent study confirms that women who are depressed during pregnancy are more likely to experience adverse pregnancy outcomes such as preterm or cesaerean delivery and small or underweight babies. However, antidepressant treatment improved outcomes for pregnant women with depression.
The 2016 study by Kartik K. Venkatesh and colleagues in the journal Obstetrics & Gynecology included 7,267 women who gave birth after at least 20 weeks of pregnancy. About 11% of the women screened positive for depression during their pregnancy. Depressed mothers-to-be were more likely to give birth before 37 weeks and before 32 weeks compared to nondepressed mothers-to-be. The depressed women were also more likely to deliver small babies or babies weighing under 2500g.
About 7% of the women in the study received antidepressant medication. Compared to nondepressed women, the women taking antidepressants did not have greater rates of early delivery or small babies. However, the authors caution that because so few women received antidepressants, the study does not reveal whether antidepressants improve outcomes for depressed pregnant women.
The Course and Outcome of Bipolar Youth study, or COBY, has been collecting information on young people with bipolar disorder and tracking their symptoms into adulthood since 2000. A 2015 study by Benjamin I. Golstein in the Journal of Clinical Psychiatry analyzed COBY data, identifying links between higher than average levels of inflammatory markers measured in the blood and participants’ histories of illness and familial risk factors.
High levels of the inflammatory marker hsCRP were associated with longer duration of illness, substance use disorder, and family history of suicide attempts or completed suicides. High levels of TNF-alpha were linked to suicide attempts, self-injury behaviors, and family history of substance use disorders. IL-6 was also linked to family history of substance use disorders.
There were also links between inflammatory markers and participants’ symptoms over the 6 months leading up to the blood tests. Levels of the inflammatory marker TNF-alpha were linked to the percentage of weeks patients had psychotic symptoms. Levels of IL-6 were associated with percentage of weeks with subthreshold mood symptoms and also with any suicide attempt. Levels of HsCRP were linked to maximum severity of depressive symptoms.
It is possible that targeting the elevated levels of inflammatory markers with anti-inflammatory treatments could improve patients’ response to treatments, but this topic requires further study.
E-cigarettes are not regulated to the same extent that cigarettes are by the US Food and Drug Administration, so their contents remain a bit of a mystery. A 2016 study by Vicky Yu and colleagues in Oral Oncology determined that even e-cigarettes without nicotine cause cell damage.
The researchers created an extract from two different brands of e-cigarettes. When they added the extract to human cells in a Petri dish, the cells showed signs of damage (including broken DNA strands) and death compared to untreated cells.
The researchers tested e-cigarettes both with and without nicotine, and those that contained nicotine showed even more signs of cell damage and death after exposure to the contents of the e-cigarette.
Other ingredients that have been identified in e-cigarettes include formaldehyde, which is known to be a carcinogen, and diacetyl, a flavoring agent.
Yu and colleagues suggest that e-cigarettes are not as safe as their marketing would suggest. The researchers hope to identify more of the ingredients in e-cigarettes.
Stimulants are one of the most common medications prescribed to children and adolescents, typically for attention deficit hyperactivity disorder (ADHD). In children of parents with major depression, bipolar disorder, or schizophrenia, stimulant use may come with a risk of psychotic symptoms. A 2016 study by L.E. MacKenzie and colleagues in the journal Pediatrics reported that among children and youth whose parents had one of these psychiatric illnesses, 62.5% of those who had taken stimulants had current psychotic symptoms, compared to only 27.4% of those who had not taken stimulants. The participants with psychotic symptoms tended to have hallucinations that occurred while they were taking stimulants. Doctors may want to consider whether parents have a history of psychiatric illness when deciding whether to prescribe stimulants to children and adolescents with ADHD. Activation is a common side effect of antidepressants in children who have a parent with bipolar disorder. Young people taking stimulants for ADHD should be monitored for psychotic symptoms, particularly if they have a parent with a history of depression, bipolar disorder, or schizophrenia.
A change in a person’s sense of humor could be an early indicator of dementia, according to a 2015 article by Jason Warren and colleagues in the Journal of Alzheimer’s Disease. The changes can appear as early as 10 years before a diagnosis of dementia. Almost all participants who would go on to be diagnosed with frontotemporal dementia showed an increased preference for slapstick humor over satirical or absurdist compared with those who would not. In contrast, changes in sense of humor appeared in less than half of those who would go on to be diagnosed with Alzheimer’s disease, indicating that changes in sense of humor may allow doctors to distinguish between different types of dementia.
The study has some limitations. It was small (48 patients) and relied on patients’ memory of what kind of humor they enjoyed 15 years earlier. More research is needed to clarify the link between changes in humor preferences and dementia.
Warren suggests that changes in humor appear before other warning signs of dementia, such as memory loss. He called humor a type of “stress test” for the brain, since getting a joke can require a quick shift in perspective.
A 2015 study by Rene L. Olvera and colleagues in the Journal of Clinical Psychiatry indicated that among 1,768 Mexican-Americans living along the border from 2004–2010, 30% were currently depressed, 14% had severe depression, and 52% were obese. Women were more likely to be depressed, and more likely to have severe depression. Other factors making depression more likely included low education, obesity, low levels of “good” cholesterol, and larger waist circumference. Low education and extreme obesity were also linked to severe depression.
In a commentary on the article in the same issue, researcher Susan L. McElroy wrote that “the medical field needs to firmly accept that obesity is a risk factor for depression and, conversely, that depression is a risk factor of obesity.” She suggested that people with obesity, those who carry excess weight around their middles, and those who have related metabolic symptoms such as poor cholesterol should all be evaluated for depression. Likewise, those with depression should have their weight and body measures monitored. People with both obesity and depression should be evaluated for disordered eating.
New research shows that bipolar disorder risk is higher in the US than in the Netherlands. At the 2015 meeting of the American Academy of Child and Adolescent Psychiatry, researchers Manon Hillegers and Esther Mesman described a study in which they compared the offspring of mothers with bipolar disorder in the US to those in the Netherlands. The offspring ranged in age from 10–18.
In the US, the mothers had, on average, an earlier age of onset, more substance abuse comorbidity, and were more likely to have been diagnosed with bipolar II disorder. Among the US offspring, 66% had been diagnosed with a psychiatric illness compared to 44% of the Dutch offspring. This included significantly higher rates of anxiety, ADHD, and disruptive behavior disorders in the US offspring. Among the offspring who had been diagnosed with a mood disorder, 80% of those in the US had other additional psychiatric disorders, but only 34% of the Dutch did. Bipolar disorder is more rare among children under the age of 12 in the Netherlands compared to the US.
Dutch children and adolescents were typically treated with lithium and with only one drug at a time. In the US, lithium is less widely used, and simultaneous treatment with several medications (usually including atypical antipsychotics) is common.
Editor’s Note: The research by Hillegers and Mesman replicates research by this editor (Robert M. Post) and colleagues that compared bipolar disorder incidence and severity in the US, Germany, and the Netherlands. Other comparisons have been made between the US and Europe. A 2014 article by Frank Bellivier and colleagues in the World Journal of Biological Psychiatry also showed that bipolar disorder onset occurs earlier in the US than in 10 different European countries, while Bruno Etain and colleagues found that bipolar disorder onset occurs earlier in the US than in France in a 2012 article in the Journal of Clinical Psychiatry.
Together this research shows that bipolar disorder is more serious in the US than in a number of European countries. Two-thirds of adults with bipolar disorder report that their illness began in childhood or adolescence. Most of these cases are not properly diagnosed or treated. A concerted effort must be made by the medical establishment and healthcare policymakers in the US to provide better and earlier treatment of bipolar illness.