Do you find it hard to just "get over it" when a sibling criticizes your caregiving abilities? How about when your spouse snaps at you after you had to re-schedule your date night for the third time in a row so you could look after mom?

If you answered "yes" to either of these questions, you might be grappling with depression.

Research has shown that people who are clinically depressed tend to be more easily offended and have a hard time letting go of negative social interactions. Now, scientists from the University of Illinois at Chicago, the University of Michigan Medical School and Stony Brook University believe they know why.

How the brain helps you deal with pain

As it turns out, that the brains of people who suffer from untreated depression don't respond as well to pain (both physical and emotional), when compared to those without the condition.

"Every day we experience positive and negative social interactions," says lead study author David Hsu, Ph.D., assistant professor at the Stony Brook School of Medicine in a press release. "Our findings suggest that a depressed person's ability to regulate emotions during these interactions is compromised…This may be one reason for depression's tendency to linger or return, especially in a negative social environment."

It all comes down to the opioid system—a group of interconnected neurons that produce three key types of pain-relieving opioids: dynorphins, beta-endorphin and the met-and leu-enkephalins. When a person experiences physical or emotional duress, the opioid system regulates the body's pain response by releasing these natural painkillers.

The opioid system in depressed people simply doesn't respond as strongly as it does in non-depressed people.

When researchers conducted brain scans on individuals who'd been subjected to social rejection during a fictitious online dating scenario, they found that the opioid systems of non-depressed individuals released larger quantities of feel-good chemicals to combat the ensuing emotional pain than the brains of those who were depressed.

Interestingly, a similar thing happened when study participants encountered reciprocal interest from their would-be beaus. Non-depressed individuals experienced a more prolonged natural high than those with depression—again, due to visible differences in the opioid system's response.

Hsu and his team believe their findings point to the existence of certain sub-types of depression, and will hopefully lead to more targeted and effective forms of treatment for people with mental condition.

Spotting and stopping depression

Clinical depression is a complex disorder that affects the lives of millions of men and women. Older adults and their caregivers are particularly prone to becoming depressed, due to the isolation and psychological stress that all too often accompany the aging process.

Common symptoms of depression include: insomnia, fatigue, feeling hopeless/worthless, changes in appetite, aches and pains that are resistant to treatment, irritability, anxiousness, trouble concentrating and lack of interest in hobbies.

Making efforts to stay socially engaged with friends and family, and taking a break from caregiving every once in a while are two key ways that family caregivers can fend off depression and prevent burnout.

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However, for people with serious depression, more dramatic intervention may be required.

Fortunately, there are a variety of treatment options available for people who are dealing with depression, from psychological counseling to prescription medication. If you suspect that you or someone you love is suffering from depression, seek the help of a mental health counselor or health care professional.