Happy Holidays! (Hopefully)
This conversation explores the groundbreaking research on contagious depression, focusing on the establishment of an animal model to study its mechanisms and effects. The discussion highlights the implications of psychiatric illnesses spreading through social interactions, particularly within familial and friendship circles. The findings reveal that healthy rats can exhibit depressive behaviors after cohabiting with depressed counterparts, marking a significant advancement in understanding mental health contagion.
It’s a bonus!
Speaking of the environmental, cognitive, and emotional bases of depression, in the midst of the family-contact season, I bring to you with no need for further introduction, the following paper:
A New Method for Inducing a Depression-Like Behavior in Rats
Zeldetz et al
Journal of visualized experiments 2018
Where they say:
Contagious depression is a phenomenon that is yet to be fully recognized and this stems from insufficient material on the subject. (studies have shown) that contagious depression increases the likelihood of families and friends of a depressed individual exhibiting depressive behaviors.
Tests carried out in recent times have suggested that psychiatric illnesses could be easily spread to healthy individuals via contagion1. In this case, it is termed social contagion and is spread through affect, attitude, or behavior. This only requires one depressed individual to interact with one or more healthy individuals, thereby facilitating the sharing of emotion. Social relationships are hence a very important component of mood, as they define the transfer of emotions from one individual to the other, by way of mimicry and "emotional contagion".
Time frames for contagion to take effect vary2, inevitably depending on the severity of the emotion and the strength of resistance of the recipient.
At the moment, there is no existing format for studying the mechanism of action, prevention, containment, and treatment of contagious depression. The purpose of this study, therefore, was to establish the first animal model of contagious depression.
The test
Depression is induced in rats by subjecting them to several manipulations of chronic unpredictable stress (CUS) over 5 weeks, as described in the protocol. 30 social groups were created from the combination of CUS-exposed rats and naïve rats.
This proposed depression-contagion protocol in animals consists mainly of cohabiting chronic unpredictable stress (CUS) -exposed and healthy rats for 5 weeks. To ensure that this method works, a series of tests are carried out - first, the sucrose preference test upon inducing depression to rats, then, the sucrose preference test, alongside the open field and forced-swim tests at the end of the cohabitation period.
Limitations
The difference between the sucrose uptake and water uptake in the supposedly depressed rats, when compared to controlled rats, is not highly significant and is not demonstrative of a highly depressed state in the experimental rats. Also, the use of the forced-swim test would not be advisable if better alternative options can be found. The damages caused by this test are traumatic, permanent, and irreversible.
Findings
According to the results obtained with the application of this protocol, healthy rats, like humans, were negatively affected by depressed rats when housed together over an extended period. The contagiously depressed rats were affected by their already depressed counterparts after five weeks of cohabitation, establishing a distinct animal depression-contagion model for the first time. An earlier study with pigs had also suggested shared emotional statutes between depressed and healthy pigs25.
The induction of depression in rats was achieved with the application of chronic unpredictable stress (CUS). This method expresses features common to every day's socioenvironmental stressors. Archives show that CUS is the most used method of inducing depression in animals. The results obtained with this method share strong similarities with clinical symptoms and depressive-like behaviors. If it is properly used on rats, the rats can express all known depressive signs26.
The ability to bring out all depressive behaviors when applied on rats validates chronic unpredictable stress CUS as a reliable depression-inducing method with high predictability and construct validity27, 28. The chronic unpredictable stress CUS method is equally used as an animal depression model to analyze cellular and molecular mechanisms of depression's pathophysiology, as well as to study the mechanism of action of antidepressants29,30,31,32,33.
The sucrose preference test applied after cohabitation of depressed and naïve rats enabled the evaluation of the spread of depression, resulting in the expression of depressive behaviors in both groups of rats after 5 weeks (Figure 2, Figure 3, Figure 4).
The forced-swim test20 and the open field test34,35,36,37,38,39,40 were also used to investigate depression in rats41. These methods mirror an extensive range of behavioral irregularities. The fact that there is no specific mechanism of contagion means that conscious and unconscious components could be advanced as potential hypothetical outcomes. Unconsciousness could manifest through mimicry42, by way of healthy rats copying body movements of depressed rats. Movements most likely to be reproduced are such as facial expressions and the neuron system43. Consciousness, on the other hand, could arise by means of communication methods.
One such method is co-rumination.
So… our friends and, I would say, in particular, families and partners, can spread depression far and wide.
A finding that makes incredible sense when combined with our recent discussion of the biases contained in language and the language-basis of depression. And also, when we consider the shared nature of emotions, which can easily activate unpleasant memories, interpretations of observations, memories, and expectations within us through associative neural networks.
We are more connected in mental illness than many of us – or our loved ones – would like to believe.
And that might shine some light on this challenging season of regrouping with people from the past.
The good news
Although the healthy rats became depressed when sharing housing with the depressed rats, depressed rats also became less depressed, compared to their state after chronic unpredictable stress CUS, as a result of cohabiting with their healthy counterparts.
This follows a pattern that was observed in earlier findings when depressed college students were able to contagiously become undepressed after spending time with their healthy roommates4.
There is, therefore, not only a negative impact with contagious depression, but also a reciprocal effect.
Depressed individuals have a negative bearing on healthy ones, while they themselves slightly recover from depression by virtue of being exposed to non-depressed colleagues. Such a finding might be a boost to psychiatry in tackling both depressed individuals and populations.
Which is all to say…
Mind who you allow into your mind this season.
Beware of rumination and the patterns of communication that can spark rumination.
Beware of mirroring and mimicry, causing the sharing of negative emotion.
Beware of Facades of Conformity and the role you’re expected to play in your family – it may be that of “depression acceptor” if you’re accustomed to emotional servitude and assisting.
And as much as possible, tap your positive social environments this season, and every season.
Text a friend. Facetime your partner. Meet up after (or as an alternate to) family events. Keep the jokes and positive memories flowing.
And together, you may be able to create a depressive co-immunity. To do more than survive the season.
Take care out there.
Hail yourself.
Hail your holidays – however you decide to do (or not do) them.
And CHEERS y’all. Talk to you soon.