Study identifies 75 proteins that may be related to depression in the elderly

A Brazilian study investigated whether proteins could be biological markers of geriatric depression, which affects elderly people without a previous history of the disease. In the end, the scientists looked at 75 substances that may be associated with the condition.

“The objective of the research was to better understand the biology of the disease, since, with these different proteins, we were able to tell the biological story of depression”, says Daniel Martins-de-Souza, professor of biochemistry at Unicamp and one of the authors of the study.

Published in the Journal of Proteomics, the investigation involved 50 elderly people: 19 had geriatric depression and 31 were in the control group.

The idea of ​​researching this complication came during the master’s degree in genetics and molecular biology of Lícia Silva-Costa, first author of the article.

“I was looking for a topic for my master’s and this one interested me a lot because it is a time in life when people are more vulnerable”, says Silva-Costa, who is now doing a doctorate in biochemistry at Unicamp.

Samples from all 50 study participants were taken to be analyzed in laboratories using a tool called proteomics. Through it, it is possible to map the proteins present in the blood and determine their volume in the samples.

Then, the scientists observed that 96 proteins were in a higher amount in patients with depression compared to those without the disease.

With this initial data, the authors used artificial intelligence to more accurately assess which proteins actually indicated an association between the disease and the substances. “The 96 were altered, but only the 75 generated a potential identity of geriatric depression”, explains Silva-Costa.

One of the proteins that caught Martins-de-Souza’s attention was CACNA1C. The biochemistry professor says that it plays an important role in neurons, the common cells of the human brain. “It has previously been associated with neurodevelopmental disorders, such as psychiatric ones.”

During the research, however, the substance was found in greater amounts in the blood of patients, something that should not happen. According to the researcher, this finding may be important evidence to indicate the association between substances such as CACNA1C, the greater amount of them in the blood and geriatric depression.

“The fact that we found it in the blood gives us very important evidence why this protein should not be in the blood, mainly because it has a neuronal role”, he adds.

greater risks

Another finding of the study was six specific proteins that showed a link with more critical conditions of geriatric depression. “This set of six proteins increases with more severe symptoms”, summarizes Martins-de-Souza.

For the teacher, the information is useful, as it can be used, in the future, to prevent the critical development of the disease. “This can be an interesting molecular signature in a person who is at the beginning of the disease to regulate and be treated. It would be like a biomarker to not let the disease get worse.”

Silva-Costa adds that, in general, proteins could be a target for the treatment of the disease.

“When you reduce the level of proteins, you can reduce the symptoms. It may not really treat the disease. For that, more investigations are needed into what causes depression in this age group”, he says.

Proteins as biomarkers may also be useful in diagnosing late-life depression. As the disease can occur from several causes, the exact diagnosis is more difficult. Therefore, the analysis of proteins as biological markers can be equally useful.

However, research has failed to confirm that these proteins are associated with late-life depression. In fact, the intention was to raise hypotheses that need to be better explored by other studies, with a larger sample group.