Anxiety and depression are often linked and assumed to be closely related.
But in a new study, researchers have found for the first time that depression and anxiety have different biochemical associations with inflammation and lipid (fat) metabolism.
This suggests that different, more targeted treatments may be possible to treat anxiety and depression.
The research was conducted by a team at Amsterdam UMC.
Depression and anxiety share several symptoms that have common risk factors, and often they are treated with the same drugs. Over 50% of patients with depression (Major Depressive Disorder) also have a history of anxiety.
Nevertheless, psychiatrists classify them as different disorders, although until now it has been difficult to identify biochemical evidence for this.
In the study, the scientists used blood samples from 304 people with current depression, 548 with anxiety, 531 with both depression and anxiety, 807 with remitted disorders, and 634 healthy controls.
Using a nuclear magnetic resonance detector they tested for associations between 40 metabolites found in blood and symptoms of depression, and symptoms of anxiety (such as panic, pathological worry, etc.).
They found that the depressed group showed evidence of greater inflammation which was not seen in the anxious group.
In addition, the depressed group had very different amounts and types of lipids in their blood.
For example, depressed people had high levels of triglycerides, but lower levels of omega-3-fatty acids.
In contrast, those people who had anxiety disorder had a lipid composition very similar to the healthy control group.
They also found that those metabolites linked to depression were also linked to the severity of the depression: in other words, if people had more of a lipid-associated with depression, their depression tended to be worse.
In recent years, depression has been associated with disturbances in the body’s immune system and metabolism, and previous researchers have shown that depressed people tend to have different biochemical markers to those of healthy people.
However, no such analysis of such a wide set of markers has been undertaken for anxiety.
This work shows, for the first time, that the immune system and lipid metabolism changes in depressed people but not in anxious people.
The researchers hope that these findings will lead to better treatments.
The study was presented at the ECNP Congress.
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