biomarker in cell-free blood plasma which can be linked to an overactive
stress system in suicidal individuals has been measured by researchers at Lund and Malmö universities in Sweden. This biomarker can hopefully be
used in future psychiatric studies.
"We don't expect the marker to be able to predict who will try to
commit suicide, but it may serve as a biological marker indicating
greater stress exposure in vulnerable people suffering from various
psychiatric conditions such as anxiety and depression. We would like to
test the marker in future psychiatric studies and see how it is affected
by, for example, lifestyle interventions, psychotherapy and
pharmacological treatment", says Daniel Lindqvist, associate professor
of experimental psychiatry at Lund University and psychiatry resident at
‘The newly measured biological marker indicates greater stress exposure in vulnerable people suffering from various psychiatric conditions such as anxiety and depression.’
The researchers compared 37 patients who had been hospitalised at a
psychiatric clinic after attempting suicide with an equal number of
healthy control subjects. About 70% of both groups were female,
and the average age of the patients was approximately 40.
Compared to the healthy control subjects, the suicidal patients had
strikingly increased levels of mitochondrial DNA in their cell-free
The researchers also found that the large amount of mitochondrial
DNA in the plasma was linked to higher levels of cortisol in the blood.
Cortisol is an important hormone in the body's stress system and high
levels of cortisol, which have been found in depressed and suicidal
patients in previous studies, are a sign of an overactive stress system.
Previous studies have shown that depressed individuals have an
increased level of mitochondrial DNA in their immune cells and that this
is linked to stressful life events. Furthermore, studies on animals
have shown that increased stress and cortisol levels are linked to
higher mitochondrial DNA, but this is the first study to be tested on
"We believe the increased levels in suicidal patients are due to
their exposure to severe stress for longer periods than the healthy
subjects we compared them to. An increased level of cortisol can cause
the body's cells to malfunction, which in turn contributes to increased
levels of cell-free mitochondrial DNA in the blood", says Lars Ohlsson,
senior lecturer at Malmö University.
"The amount of mitochondrial DNA in cell-free plasma is a new and
interesting marker of stress that can be used in future psychiatric
studies, but the results have to be replicated in other groups of
patients as well. A key question will be how the biomarker changes over
time in connection with the patient's symptoms improving or
deteriorating", says Åsa Westrin, associate professor of clinical
psychiatry at Lund University and senior physician at Psykiatri Skåne.