"That will be us someday!" It's the sweet wish of a young couples when they spy older couples on the street, in restaurants, on the dance floor who still seem to be in love.
But the other side of that wish is this: love may have no expiration date, but all people do. Death of a partner is most likely to happen in old age, more likely to happen to older women, and is often considered to be one of the most traumatic events a person can experience. This sort of loss, or bereavement, is often related to Major Depressive Disorder (clinical depression). The most recent version of the Diagnostic and Statistical Manual (DSM-V) removed the "bereavement exclusion": thus a grieving person who exhibits the symptoms of depression may receive that diagnosis even though these symptoms are a normative response to loss of a loved one. Fried, Bockting, Arjadi, Borsboom, Amshoff, Cramer, Epskamp, Tuerlinckx, Carr, and Streoebe (2015) note that we often assume bereavement causes a person to have depression, and depression produces symptoms. This is called the "Common Cause Hypothesis" because all symptoms are thought to come from one situation: depression. However, the authors caution us that this hypothesis may not be appropriate because there are thousands of symptoms that depressed people may have, these may contradict each other (e.g.; some depressed people eat too much while other depressed people don't feel like eating at all), and risk factors, such as suicide, may vary depending on the constellation of symptoms that an individual exhibits. Instead, Fried et al. (2015) encourage us to consider a Network model. From this view, bereavement would cause symptoms, and these symptoms would create situations, such as depression. These symptoms could also interact with (influence) each other to produce such situations. To test these two viewpoints, the authors used data on depression symptoms from the Changing Lives of Older Couples (CLOC) study. First, they compared the scores on a depression test from 241 widowed seniors (from Follow-Up 1) to 274, age- and gender-matched, married seniors (from Follow-Ups 1-3). The majority of the participants were female and senior citizens. When these individuals joined the CLOC study there was no difference in their reported depression symptoms, but in the follow-up interviews, six months after the death of a spouse the bereaved seniors demonstrated slightly more of these symptoms compared to the seniors who were still married. In fact, 84 of the widowed seniors exceeded the criteria for Major Depressive Disorder by endorsing at least six symptoms. The most commons symptoms were: feeling lonely; feeling sad; feeling depressed; having trouble motivating themselves; problems sleeping; problems eating. Then Fried et al. (2015) applied complicated statistical models to see if the Common Cause or the Network frameworks would best explain the relationship between bereavement, depression, and depression symptoms. For the Common Cause model to be supported these six symptoms should be better predicted by Depression; instead four of these symptoms were better predicted by loss itself (bereavement) lending support to the Network model. Further investigation revealed that bereavement was especially linked to one symptom, feeling lonely. These results caution us to think more broadly about depression and spousal loss in older age, especially for older women. Instead of assuming that bereavement causes depression, it may be that bereavement causes a set of symptoms including loneliness. In turn, it could be that this loneliness is what eventually leads a person to experience Major Depressive Disorder. As this week's meme suggests, true love may last forever: into old age and even when the person we love is gone. With love still in our hearts but now suddenly on our own, it is easy to see how loneliness could set in. And that is a depressing thought.
Some suggest that the first popular Internet memes starred cute cats with sayings like "I can has cheezburger?." So it was natural that I chose a cat as this blog's icon and not surprising that this week's meme features a cat:
The humor comes from relating typical cat behaviors to the very serious symptoms of human depression. Specifically the DSM-V includes "changes in sleep, appetite, and decreased interest in activities" as indicators of Major Depressive Disorder and Depressive Episodes in human beings. On the other hand, there is an old adage that pets and their owners resemble each other. Maybe this trend applies not only to physical traits but also to psychological traits? We can ask the question: is their a relationship between cat ownership and depression? On one hand we have research findings that lead us to believe that having a cat, or any pet, could be protective against depression. For example, McConnell, Brown, Shoda, Stayton, and Marton (2011) conducted an experiment to determine if pets can serve as social support and reduce the sting of rejection. In their somewhat disturbingly named paper, "Friends with benefits: on the positive consequences of pet ownership," they included a study of 97 undergraduate students, who were also pet owners (76 dogs, 20 cats, one horse). The participants either wrote a detailed report about a time that they were rejected (experimental condition) or what they had done earlier that day (control). Thus the experimental condition triggered feelings of rejection whereas the control condition did not; this was verified by participants' scores on a 17 question Social Needs Scale. Next, the participants were either instructed to write about why they like their pets, why they like their best friends (human, that is), or to draw maps of their college campus. Past research demonstrated that thinking of your best friend serves as a reminder of social support, so the researchers were curious if thinking of a pet would have the same effect. Drawing a map was a neutral experience that would not be related to social support. Indeed, when they completed a second check of their emotional states the participants who had felt rejected and then thought about their pets or best friends had rebounded and now felt that their social needs were satisfied. Although the difference did not reach statistical significance, the students who thought about their pets actually had a slightly higher emotional boost than the students who thought about their best friends! Things were worse for the participants who had felt rejection and then drew maps of their campus: their social needs scores continued to plummet. Drawing the map was associated with feeling even more rejected as the study progressed! So if you are feeling low, thinking about your cat might make you feel better, but just thinking about random things to distract yourself might make you feel worse. Before you start to believe that cats are the key to avoiding depression, these findings are tempered by an earlier study also found in the McConnell et al. (2011) article. When they compared 167 pet owners and 50 non-pet owners in the university community, the pet owners were slightly less lonely and had better self-esteem, but they did not differ significantly from the non-owners on actual measures of depression. Another possibility is that the positive social support that cats provide may be undercut by a negative biological factor: Toxoplasma gondii. This protozoan can only complete its reproductive cycleinside a cat's digestive tract and can infect humans who have contact with cat poop that contaminates their food. A recent review by Hsu, Groer, and Beckie (2014) reports that 23% of the U.S. population shows no physical symptoms yet tests positive for this type of infection!
New T. gondii infections that are acquired during pregnancy can cause miscarriage, but an ongoing, undetected infection is associated with, "...mental and behavioral disorders such as schizophrenia, depression and suicide attempts" (p. 632). This is likely because the infection causes inflammation or cysts in the brain, and both could disrupt neurotransmitters such as serotonin, dopamine, and tryptophan. However, cat ownership is not considered to be a high risk factor for infection for most people: raw meat consumption or contamination from unwashed kitchen utensils are more common modes of infection. So go ahead and hug your cat to thank your pet for the social support - but, to be safe, wash your hands well after cleaning out the litter box. For all of us, if you are not a cat and find yourself sleeping too much, eating too much or too little, and you have lost all motivation it is important that you seek treatment for depression. Further reading: You can access the McConnell et al. (2011) article at your local college library. A copy of the Hsu et al. (2014) article is available online. Depression is a serious illness. The National Suicide Prevention Lifeline (1-800-273-8255) can help if you are feeling hopeless. Their website also has good information for people who would like to volunteer or donate to help others. A really fun read for anyone who likes cats: a link to Shreve, K.R., & Udell, M.A.R. (2015). What's inside your cat's head? A review of cat (Felis Silvestris catus) cognition research past, present and future. Animal Cognition, in press. BONUS: Imagine if your friends acted like cats and dogs...or watch it here and it will make you smile:
