Inflammation can interfere with the balance of neurotransmitters in the brain, making antidepressants less effective. Anti-inflammatory treatments (such as those used to treat rheumatoid arthritis) may help. In a 2016 meta-analysis published in the journal Molecular Psychiatry, researchers led by Nils Kappelmann analyzed the results of 20 clinical trials of chronic inflammatory conditions where depressive symptoms were also recorded. In a subset of 7 clinical trials that compared anti-inflammatory treatment to placebo, they found that anti-inflammatory treatment improved depressive symptoms significantly compared to placebo.
The anti-inflammatory drugs studied most often targeted the inflammatory marker tumor necrosis factor (TNF) alpha using an antibody. Some of the anti-inflammatory drugs that improved depressive symptoms were adalimumab, etanercept, infliximab, and tocilizumab.
The researchers also found that those participants with the most inflammation when they began treatment saw the largest improvement in their depression after taking anti-inflammatory treatments.
Kappelmann and colleagues suggest that inflammation may cause depression, and that anti-inflammatory drugs may be useful in the treatment of depression in people with high inflammation.
A recent study shows that psychotherapy can not only improve depression symptoms, but may also reduce the inflammation that often accompanies them.
Researcher Jean Pierre Oses and colleagues randomly assigned participants with depression to receive Supportive-Expressive psychodynamic therapy, which is designed to help patients understand conflictual relationship patterns, or an alternative therapy. Among the 47 participants who received Supportive-Expressive therapy, depression improved significantly after 16 sessions, and blood levels of the inflammatory markers interleukin-6 and TNF alpha also dropped.
The research was presented at the 2016 meeting of the Society of Biological Psychiatry.
Meta-Analysis Shows Inflammation is Common in Unipolar Depression, Bipolar Depression, and Schizophrenia
In a symposium at the 2016 meeting of the Society of Biological Psychiatry, Mark Hyman Rapaport described the results of his research group’s meta-analysis of studies comparing levels of inflammation in the blood of people with unipolar depression, bipolar depression, and schizophrenia. Rapaport and colleagues determined that people acutely ill with any of the three illnesses showed abnormally high levels of certain inflammatory proteins. These included: interleukin-1beta, interleukin-6, TNF alpha, and c-reactive protein. Those who were chronically ill showed elevations in interleukin-6.
These data are consistent with increasing evidence that inflammation also occurs in the brain. Brain inflammation can be observed by measuring translocator protein binding, a measure of brain microglial activation, using positron emission tomography (PET) scans.
Suicide and depression have both been linked to elevated levels of inflammatory cytokines in the blood and cerebrospinal fluid. A recent study finds that these inflammatory markers are also elevated in the brains of teens and depressed adults who died from suicide.
In autopsy studies, researcher Ghanshyam N. Pandey measured levels of the inflammatory cytokines interleukin-1beta, interleukin 6, and TNF-alpha in the brains of teen suicide victims, and compared these to the brains of teens who died from other causes. Pandey also measured levels of interleukin-1beta, interleukin 6, interleukin 8, interleukin 10, interleukin 13, and TNF-alpha in the prefrontal cortex of depressed adult suicide victims and compared them to levels in adults who died of other causes.
There were abnormalities in the inflammatory markers in the brains of those who died from suicide compared to their matched controls. The suicide victims had higher levels of interleukin-1beta, interleukin 6, and TNF-alpha than the controls. Among the adults, levels of the anti-inflammatory cytokine interleukin 10 were low in the suicide victims while levels of Toll-like receptors (TLR3 and TLR4), which are involved in immune mechanisms, were high.
Brain inflammation has also been observed in positron emission tomography (PET) scans of depressed patients, where signs of microglial activation can be observed. Elevated inflammatory cytokines are also found in the blood of some people with bipolar disorder, depression, and schizophrenia.
Pandey presented this research at the 2016 meeting of the Society of Biological Psychiatry.
In a symposium on inflammation’s role in psychiatric disorders at the 2016 meeting of the Society of Biological Psychiatry, researcher Carmine Pariante reviewed the considerable literature indicating that major depression is often associated with measures of inflammation. Depression has been linked to elevated blood levels of the inflammatory proteins interleukin-1, interleukin-6, TNF alpha, and c-reactive protein, with about one-third of depressed patients having an elevated level of at least one of these proteins. People with elevated inflammatory markers are also less likely to respond to traditional antidepressants such as selective serotonin reuptake inhibitors (SSRIs).
Pariante reported that in depressed people, interleukin-6 is also elevated in cerebrospinal fluid in addition to blood, suggesting that inflammation in depression extends to the central nervous system. Increased secretion of interleukin-6 has been linked to depressive behaviors in mice exposed to stress.
There is some hope that anti-inflammatory treatments can help patients who do not respond to traditional antidepressant treatment. Some anti-inflammatory medications that may eventually be used to treat depression with inflammation include the COX-1 inhibitor aspirin, the COX-2 inhibitor celecoxib (Celebrex), or the antibiotic minocycline. Each of these approaches gained some support in preliminary clinical trials, but it has not yet been established that these anti-inflammatory treatments produce a better response in people with elevated inflammatory markers.
There is growing evidence of a link between inflammation of depression. At the 2015 meeting of the Society of Biological Psychiatry, researcher Jeff Meyer summarized past studies on inflammatory markers. These are measurements, for example of certain proteins in the blood, that indicate the presence of inflammation in the body.
Common inflammatory markers that have been linked to depression include IL-6, TNF-alpha, and c-reactive protein. At the meeting, Meyer reviewed the findings on each of these. Twelve studies showed that IL-6 levels are elevated in the blood of patients with depression. Four studies had non-significant results of link between IL-6 and depression, and Meyer found no studies indicating that IL-6 levels were lower in those with depression. Similarly, for TNF-alpha, Meyer found 11 studies linking elevated TNF-alpha with depression, four with non-significant results, and none showing a negative relationship between TNF-alpha and depression. For c-reactive protein, six studies showed that c-reactive protein was elevated in people with depression, six had non-significant results, and none indicated that c-reactive protein was lower in depressed patients.
Most studies that have linked inflammation to depression have done so by measuring inflammatory markers in the blood. It is more difficult to measure inflammation in the brain of living people, but Meyer has taken advantage of new developments in positron emission tomography (PET) scans to measure translocator protein binding, which illustrates when microglia are activated. Microglial activation is a sign of inflammation. Translocator protein binding was elevated by about 30% in the prefrontal cortex, anterior cingulate cortex, and insula in study participants who showed symptoms of a major depressive episode compared to healthy control participants. The implication is that the depressed people with elevated translocator protein binding have more brain inflammation, probably via microglial activation.
The antibiotic minocycline reduces microglial activation. It would be interesting to see if minocycline might have antidepressant effects in people with depression symptoms and elevated translocator protein binding.
People with bipolar disorder often show signs of inflammation. These could eventually help clarify diagnosis, illness activity, and treatment response, and predict illness progression. Previous studies have shown increases in c-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) in adults with mood disorder. These high levels tend to improve with medications, are related to illness severity, and are also related to manic and mixed states.
At the 2013 meeting of the American Academy of Child and Adolescent Psychiatry (AACAP), Ben Goldstein reported on a study that examined levels of TNF alpha, IL-6, and high sensitivity CRP (hsCRP) in 123 adolescents with an average age of 20.4 years, who had been ill for an average of 12.7 years.
CRP levels in adolescents with bipolar illness were equivalent to those with rheumatoid arthritis, and much higher than healthy controls. In children with bipolar disorder, higher levels of CRP were related to more time symptomatic. High hsCRP was related to lower socio-economic status and to substance abuse disorders.
Increases in IL-6 were linked to a longer time to achieve remission and more weeks depressed. High IL-6 was related to duration of illness, positive family history of substance use, and family conflict.
High TNF alpha was related to low socioeconomic status (SES), self-injury, suicidal ideation, and positive life events.
Goldstein said studies of these markers could eventually lead to therapeutic advances, but the process would be long and would require several steps: proof of concept studies, prospective validation studies in independent samples, and demonstration of clinical gains over standard predictive markers, culminating in enhanced patient care and outcome through better, faster prediction of response.
Editor’s Note: Ideally clinicians could jump ahead by immediately attempting to determine whether adding a medication with direct anti-inflammatory effects could enhance therapeutic effects in children with elevated inflammatory markers. Treating inflammation could also theoretically help prevent cognitive deterioration and decrease the considerable risk for cardiovascular dysfunction in patients with bipolar disorder.
There appears to be a link between inflammation and depression. In the journal Neuropsychopharmacology, Cattanes et al. reported in 2013 that compared to controls, depressed patients had significantly higher baseline levels of inflammatory cytokines, less glucocorticoid receptor function, less neuroplasticity, and fewer neuroprotective factors. Certain variables predicted response to treatment, others were seen only in responders, and still others changed in everyone with antidepressant treatment.
Higher baseline levels of inflammatory markers interleukin IB, macrophage inhibitory factor (MIF), and tumor necrosis factor TNF? were each associated with nonresponse to antidepressant treatment, and the three combined accounted for 50% of the variance in response—that is, they were the major predictor of whether a patient responded to treatment.
Levels of other factors changed in only those patients who responded well to antidepressants. The biggest changes were the normalization in levels of the neurotrophic factors BDNF and VEGF.
Several other markers normalized with antidepressant treatment regardless of whether the patients responded to treatment, and these included decreases in cytokines interleukin-IB and MIF and improved glucocorticoid receptor function.
The three different kinds of findings about these biomarkers were observed regardless of what type of antidepressant was used—SSRI versus tricyclic nortriptyline (which blocks norepinephrine reuptake).
Editor’s Note: This study replicates other studies in depression where signs of inflammation have been observed, including increases in inflammatory cytokines, decreases in glucocorticoid receptor function (needed to suppress high levels of the stress hormone cortisol) and lower levels of neuroplasticity and neuroprotection markers. This, however, is one of the first studies to show that levels of these markers at baseline may predict response to antidepressant treatment.
Also novel are the findings that while some high interleukin levels at baseline predicted antidepressant non-response, other ones normalized only in responders, and still others changed with treatment independent of whether the patients’ depression improved. These exciting findings require replication, but suggest the future possibility of personalized medicine, that is, choosing medications based on an individual biochemical marker profile. Eventually direct use of anti-inflammatory agents may be necessary in those with the highest levels of cytokines (predicting non-response to conventional antidepressant treatment). The same types of studies are needed in bipolar depression to determine the relationship between these inflammatory markers and treatment response.