"Chronic Fatigue and Personality: A Twin Study of Causal Pathways and Shared Liabilities" (incl CFS)

[Enid]

Yup - their egos seem to be an enormous problem. At least I met one - a Neurologist who had the humility to recognise he did not understand all his findings and would I find an ME specialist to whom he would release all his test findings.

 

[WillowJ]

Aside from discussions of illness, personality is generally thought to be a trait which is (after one grows up) relatively fixed.

Then there is this odd though that illness is associated with personality or a change in personality (in some studies this change can be demonstrated [refs]).

However the personality trait assessments were formulated for and normed in healthy persons. If you go around asking an ill person questions about whether is is concerned about not fitting in, and questions about whether others do more for them than they do for others, or whether they need to have specific routines or diets (or have a hard time with changes; I can't recall how the questions for OCD are worded)... it's entirely possible that what you are in fact measuring is the presence of illness and disability, not personality traits. (this is why the control group should be an illness group which is also debilitating, etc. Having a poorly understood illness could also contribute to such artifacts)

Stein E. Clinical Guidelines for Psychiatrists: Assessment and Treatment of Patients with ME/CFS. (2005) http://www.mecfs.org.au/media/resources/Article-ESteinPsychiatricCFSGuideline05.pdf

Courjaret J, Schotte CK, Wijnants H, Moorkens G, Cosyns P. (U Hosp Antwerp) “Chronic fatigue syndrome and DSM-IV personality disorders.” J Psychosom Res. 2009 Jan;66(1):13-20. Epub 2008 Nov 22. PMID: 19073288.

RESULTS: The results indicate a striking lack of statistical significant differences between the CFS sample and the Flemish control group at the level of dimensional Trait scores, number of criteria, and prevalence rates of personality disorder diagnoses.

see also the discussion on a related paper:
http://forums.phoenixrising.me/inde...findings-from-a-population-based-study.14495/

 

[Valentijn]

However the personality trait assessments were formulated for and normed in healthy persons. If you go around asking an ill person questions about whether is is concerned about not fitting in, and questions about whether others do more for them than they do for others, or whether they need to have specific routines or diets (or have a hard time with changes; I can't recall how the questions for OCD are worded)... it's entirely possible that what you are in fact measuring is the presence of illness and disability, not personality traits. (this is why the control group should be an illness group which is also debilitating, etc. Having a poorly understood illness could also contribute to such artifacts)

I agree completely. There are two basic types of questionnaires in the mood/psychiatric category: 1) questionnaires which directly ask patients how they feel, and 2) questionnaires which ask patients what they do and then make assumptions about how patients feel based on what they do. The first sort would probably work fine with physically limited patients, but the second sort assumes that any abnormality in behavior is purely voluntary.

To the psychs the second sort probably feels more "clever", since it tricks those psychiatry hating/fearing patients into revealing their true colors And it leaves a market open for psychiatrists to develop new and more convoluted questionnaires, thus giving their lives a sense of meaning. And I do think that certain groups deliberately take advantage of the unacknowledged ambiguity of those questionnaires to carve out a niche in "treating" the physically ill for their "co-morbid psychiatric conditions".

 

[Dolphin]

Getting back to discussing what this specific paper found.

Emotional Instability

Figure 2 presents the MZ and DZ within-twin pair associations of emotional instability with both definitions of chronic fatigue. Although the MZ within-twin pair associations with both definitions of fatigue were not reliably different from zero (B’s for both definitions<−0.004, p’s>0.70), the DZ within-twin pair associations were significant (B=0.086, p=0.003 for chronic fatigue of 6 months or longer; B=0.100, p=0.001 for CFS-like illness). This finding suggests that the association between emotional instability and both definitions of chronic fatigue is almost completely confounded by common genetic mechanisms, regardless of the stringency of diagnostic criteria.

MZ twins =Monozygotic twins = "identical twins"
DZ twins = Dizygotic twins = "nonidentical twins".

Monozygotic and Dizygotic twins are assumed to have similar environmental effects, but DZ twins only share half the genes.

So differences like above (dramatically shown in a figure) are due to "genes".

 

[Dolphin]

This is what they concluded on introversion/extraversion:

In contrast to our results on emotional instability, our finding of an association between low extraversion and both definitions of chronic fatigue differed from those of Kato and colleagues [22], who found no such association. Our finding suggests that this association is not driven by familial factors. The lack of familial confounding in our data is consistent with the possibility that low extraversion and chronic fatigue have causal dynamics [37]. However, these findings do not allow us to determine whether low extraversion predisposes a person to develop a fatiguing illness or whether having a disabling illness such as CFS pushes a person down the extraversion scale over time in the direction of greater introversion, which can then amplify and maintain the condition. Nevertheless, our finding of a potentially causal association, combined with Kato and colleagues’ finding that preexisting introversion did not increase the risk for subsequent development of fatiguing illness, suggests that introversion is likely to be the result of CFS rather than the cause. Prospective studies are needed to clarify the robustness of this association and the direction of causality.

 

[Dolphin]

What I found annoying is the promotion of CBT and GET in this study.

Even with these mixed results, extraversion is a potentially important factor in understanding how CFS develops and is sustained in individuals because extraversion correlates with subjective well-being [29–32] and guiding a person to act in a more extraverted manner can increase subjective well-being [33]. Such an effect, along with the positive effects of extraversion on exercise behavior [24–26], may explain some of the benefits of cognitive behavioral and graded exercise therapies in CFS [34–36]. That is, acting in an extraverted way may have a “navigational effect” that positively alters the daily experience of fatigue, pain, and associated negative mood states described by people with CFS.

Why make "subjective well-being" the aim? If one is treating Cancer, say, the size of the tumour is the most important thing, rather than "subjective well-being".

Regarding CBT, studies like the three looked at in Wiborg et al. (2010) suggest people aren't necessarily more active in total. So very speculative.

The slight attenuation of the effect in MZ compared to DZ pairs suggests that the association between low extraversion and both definitions of chronic fatigue may be somewhat confounded by familial factors. Nevertheless, the strong association that remained in the MZ pairs, even when controlling for shared genetics, is consistent with the hypothesis that, to an important degree, extraversion affects fatigue, fatigue affects extraversion, and the relationship may be mutually reinforcing, regardless of the initial direction of causation.

There was no evidence in this study that I could see that showed the relationship was reinforcing. This part is taken from the results section - if they want to speculate, I think it would have been better in the discussion section to make it clear what was and wasn't found.

These results may have important implications for clinical interventions for people with CFS. Considerable evidence suggests that extraverted individuals tend to achieve greater levels of subjective well-being than introverted individuals [30, 31]. Self-reports and spousal reports of dispositional extraversion and overall positive affect have shown reasonably robust correlations that vary in the range of 0.10 to 0.70 [29, 32] across various ages and cultures [46]. Evidence also indicates that guiding introverted people toward acting as if they were extraverted can increase subjective well-being [33]. That is, positive affect tends to follow on what individuals do regardless of what traits they have or who they are [33, 47]. Therefore, this navigational effect of “doing” may positively alter a person’s daily experience of fatigue and well-being. Clinically, therapeutic efforts can capitalize on this effect to reverse the slide toward greater introversion in everyday life —an outcome to which individuals with CFS may be prone. Consistent with this approach, several randomized clinical trials have demonstrated that cognitive–behavioral and graded exercise interventions that focus on increasing social and physical activity are efficacious in lowering fatigue and improving physical function in people with CFS [36, 48–54]. In addition, higher extraversion has also been shown to predict positive response to both antidepressant medication and cognitive– behavioral interventions [34, 35].

Again, is one interested in "subjective well-being" or actually treating the illness? Making people more extraverted might mean they don't self-report as ill, but that's not dealing with the core illness.

Also, CBT and graded activity programs doesn't necessarily mean people do more in total.

An alternative interpretation of this is that graded activity-oriented CBT and graded activity programs do make people more extraverted and that could wholly or partly explain some subjective improvements reported (without objective improvements).

Concluding paragraph:

In conclusion, we found that higher emotional instability and lower extraversion were linked to chronic fatigue, such that emotional instability acted through shared genetic mechanisms and extraversion acted primarily through a bidirectional, causal pathway. Behavioral prevention and intervention strategies can be used to mitigate or reverse the development and maintenance of CFS and other fatiguing illness. Taking an extraverted approach in day-to-day interactions may have a “navigational” effect that lowers morbidity and improves subjective well-being and functioning in people who suffer from chronic fatigue.

I'm pretty sure extraversion hasn't been measured before and after CBT or GET in CFS, so what they are saying is all very speculative, particularly for a concluding paragraph. Similarly, going the other way, there are no specific studies mentioned showing that any intervention that caused people with CFS to be more extraverted, improved scores.

I've just noticed in the abstract, they also have this in the conclusions section:

Whereas emotional instability and chronic fatigue are linked by shared genetic mechanisms, the relationship with extraversion may be causal and bidirectional.

They've produced no evidence that it was bidirectional. All they found was a correlation/association between the two.

 

[Valentijn]

What I found annoying is the promotion of CBT and GET in this study.

Too many idiot researchers that are either unable or unwilling to critically read the existing research. They just look at the abstracts which say "CBT/GET IS FUCKING AWESOME!!!11!!!ONE!11!!" and treat it as being indisputable truth.

 

[vamah]

I am somewhat at a loss vis-a-vis the concept that telling introverts to "act" like extroverts is a helpful suggestion. I would think that encouraging people to act in a manner that is at odds with their natural tendancies would be stressful and therefore detrimental to good health.

Of course, this is assuming that you are using a Myers-Briggs type definition of introversion and extroversion, which views those qualities as innate and equally valid. This study, I am thinking, leans more towards the (ignorant and infurriating) view that introverts are just self-centered, while extroverts are more focused on other people.

This notion always makes me want to scream, "How are we the ones who are self centered when its the extroverts saying the world would be a better place if only everyone were just like them?!!!"

I am perfectly capable of "acting" extroverted in social situations that require it, but I will always hate it, it will always feel uncomfortable and stressfull for me, and I will always be relieved to get out of those situations. Oh, and it will never make me feel healthier, subjectively or otherwise.

 

[Little Bluestem]

This notion always makes me want to scream, "How are we the ones who are self centered when its the extroverts saying the world would be a better place if only everyone were just like them?!!!"

Double LIKE!

 

[percyval577]

Rather the interesting finding, I think, is:

While 42% of the MZ twin pairs were concordant for chronic fatigue of six months or longer,
only 29% of the DZ twin pairs were concordant for this definition of chronic fatigue.

Likewise, 26% of the MZ and 13% of the DZ twin pairs were concordant for CFS-like illness.

The higher concordance rates in MZ than in DZ twin pairs suggest that chronic fatigue and CFS-like illness are heritable, a condition that is necessary for further analysis of genetic confounding between ...

The rest of the study may be subject to Occham´s razor, I guess.

The other finding from 2001 Buchwald et al points less ambitious in blabla into the same direction. From the abstract:

For idiopathic chronic fatigue, the concordance rates were 55% in monozygotic and 19% in dizygotic twins (p =.042).

The estimated heritability in liability was
19% (95% confidence interval = 0-56) for chronic fatigue > or =6 months,
30% (95% confidence interval = 0-81) for chronic fatigue not explained by medical conditions, and
51% (95% confidence interval = 7-96) for idiopathic chronic fatigue.


These results provide evidence supporting the familial aggregation of fatigue and suggest that genes may play a role in the etiology of chronic fatigue syndrome.

Even more plain, although it´s not said (in the abstract) what the criteria are (the CCC have been implemented in 2003 only), whereas the 2013 article uses the 1994 Fukuda criteria.