Saturday, 24 January 2009

The Bipolar Schizophrenic Overlap

Mo's blog linked to this Lancet article.

Interest in the much-debated possibility of genetic overlap between schizophrenia and bipolar disorder has been restimulated by molecular genetic studies, which have led to reappraisal of previous evidence from genetic epidemiology. Most previous genetic epidemiological studies have been underpowered to investigate the question of diagnostic overlap. This study, however, included more than 2 million nuclear families; the researchers merged data from the Swedish multigeneration population register and the Swedish hospital discharge register. The results clearly show increased risks of both schizophrenia and bipolar disorder for first-degree relatives of probands with either disorder. Furthermore, evidence from half-siblings and offspring adopted away shows that this is due substantially to genetic factors.

The Kraepelinesque Dichotomy is dead! (I've always wanted to say that.) Kraepelin, as you all know, differentiated what he called Manic-Depressive Insanity from Dementia Praecox (what we now call schizophrenia). In fact, though, Kraepelin later said:

No experienced psychiatrist will deny that there is an alarmingly large number of cases in which it seems impossible, in spite of the most careful observation to make a firm diagnosis... it is becoming increasingly clear that we cannot distinguish satisfactorily between these two illnesses and this raises the suspicion that our formulation of the problem may be incorrect. (1920)

Seriously, it has been on the cards for a while. The overlap has been highlighted recently (to my certain knowledge) since at least 1995 (Eysenck: Genius, the Natural History of Creativity - you can read some of the book here - quite interesting, and refreshingly straightforward (why are psychologists more readable than psychiatrists?) though I may have been feeling mildly grandiose when I ordered it from Amazon).

Various studies comparing people with schizophrenia and manic depression with the likelihood of their children inheriting either condition: Rosenthal (1970), Penrose (1968), Powell et al (1973), Elsasser (1952), Schulz (1940), Pollock and Maltzberg (1940), Slater (1953), etc, etc, etc... all of these show that one type of illness may beget the other to a significantly higher degree than would be expected by chance (eg, Rosenthal found that the children of manic depressives had a 2.3% chance of being schizophrenic, compared to 0.8% in the general population).

On the other hand - there is evidence that there is a difference between the two conditions. I commented on Mo's blog: "if there were five genes, and four of them (say ABCD) made you schizophrenic and another four (say BCDE) made you bipolar" then it would be easy to see how the shared likelihood of transmission could occur, but still differentiate the two conditions. Some studies, Kant (1942), Weingberg and Lobstein (1943), Vaillant (1962) found that relatives of schizophrenics who didn't recover showed a greater ratio in first degree relatives of schizophrenia to manic depression, compared to relatives of recovered schizophrenics, where the ratio was reversed. The ratios varied between 5:1/1:5 and 7:1/1:7.

Studies have been carried out seeing how often different psychiatrists' diagnoses accord with each other. The figures for agreement are generally around 59%. Or on the other hand, 41% of the time, someone gets it wrong. This obviously (?) cannot purely be down to incompetence (thus he prays).

However, this Swedish study seems very large, and hopefully should make more of a splash in the murky waters of the pond.

I've rambled on long enough to little purpose. I'll finish with a quote from Eysenck:

As regards the generality of 'psychosis', it seems clear that there are definite genetic links between different diagnostic categories (schizophrenia, manic-depressive disorder, schizo-affective disorder, unipolar disorder) which make it impossible to regard them as entirely separate disease entities. Some specificity there undoubtedly is, but there is also a generality of disorder which links all these disorders and their sub-classifications and diagnoses together to form one end of the psychoticism continuum, with a severity gradient placing schizophrenia at the extreme end, followed by schizo-affective disorder, manic-depressive disorder and finally unipolar illness.

Back to the schizoaffective spectrum, eh? Or since that was written in the mid 90s, that should be towards the schizoaffective spectrum.

P.S. On a brighter note, I hope this will reduce the stigma that gets shoved at schizophrenia. I find it irritates me when I read someone with (say) manic depression 'writing off' people with something 'worse'. Our 'shared heritage' he said, raising an eyebrow in sympathetic amusement, should give us pause.


Update. 4.15. It's hard and crunchy and very frosty outside. No less than five cockerels are competing. The stars are malevolent in their gleam. I feel calm, relaxed, but utterly untricked of sleepiness. Nothing unpleasant, just... just... oh well... you all know I'm sure what follows on from "just..."... But already?


La-reve said...

thanks I found this very interesting. Thanks for sharing your research here.And taking time to post. Hope you got some sleep.

Mandy said...

Hi D

I am usually out of my pram on how Stigma is being rammed down people's throats whilst all the money spent on anti stigma campaigns does nothing to break down any stigma there is.

However, when it is people with MH problems (as individuals) talking about stigma I am more inclined to listen (or in this case read), objectively.

I think the latest experience I have had with local council is interesting in that they (a customer care advisor) informed me that just because I have Bipolar Disorder doesn't mean I am excempt from paying council tax (there is an excemption for people with serious mental disability). I assume and I only assume, so could be wrong, that people with schizophrenia would be identified as excempt from paying council tax on grounds of serious mental disability..although I would like some evidence based research to look at this sort of theory of mine.

What this says to me is that people with schizophrenia are seen as more disabled than those with bipolar. Perhaps they are and I am stigmatizing in what I write. Not intentional.

When I spoke to a welfare benefits officer she told me that the excemption for council tax is due to 2 things 1) lack of in not being that intelligent (something I found personally irritating) and 2) lack of mobility.

Does this mean in order to be entitled to certain benefits people have to be 'lacking intelligence'? If so, well you can't get anymore stigmatising than that. The contradictory nature of such stigma also means that people who have and i put this in quotation marks 'learning difficulties' would be less likely to access benefits because at least I have the so called intelligence to ask questions of my care co-ordinator who then passes it on to a welfare benefits officer. I assume that others might not know what benefits are available to them or what questions to ask of those who are in some ways 'responisible for their care'.

I am sorry if I have rambled on. Getting quite confused myself a last word I think the Government bodies are the ones that are stigmatising people. They make the assumptions and half cock rules and they also (deliberately or otherwise) deny access to information to people who are entitled to have it.

P.S. Glad to read that you got to a calm, relaxed place and slept. Hope that happens more for you. :>)

Mandy said...

P.P.S. I feel need to write, and apologise for hogging this, that I do not think people with schizophrenia lack intelligence. Far from it, my experience of being in acute care and amongst people who have this illness is that they are very intelligent. Such are the people I have come across and I make my judgement on that. :>)

Abysmal Musings said...

Thanks both - don't apologise Mandy - no need - hog as much as you like!

Yeah, sleep came around 6.00... got a bit in before the rumpussing rampage of small boys attacked.

Mo said...

D: "The Kraepelinesque Dichotomy is dead!"....great name for an album.

Mandy: "When I spoke to a welfare benefits officer she told me that the excemption for council tax is due to 2 things 1) lack of in not being that intelligent (something I found personally irritating) and 2) lack of mobility.".

Well I don't know how things are in England but up here North of Hadrian's Wall, council tax exemption is related to (as well as income, savings, tax credits etc.) the two parts of Disability Living Allowance; 1) the care component and 2) the mobility component. It has nothing to do with your clinical diagnosis, or as your benefits officer calls it "lack of savvy". Lots of folks with bipolar disorder are on the high level of DLA as they may require encouragement and supervision due to self neglect when down and dangerous behaviour when up. Even highly intelligent folks like me ;o)

Immi said...

Garrrrrrr stupid thing ate my post.
But basically: I'm living. And it's silly to think schizophrenia is "worse" than bipolar. Someone with manic depression who was never psychotic thinks that maybe? Each has its definite downside. Eh whatever.

Tempest said...

I don't think the argument of which is worse, bipolar or schizophrenia, is a very productive one. Each case should be determined on an individual level, since that's how it's experienced, and impact on life should be part of the criteria for judging how bad someone has it.

Putting the two on the same spectrum, in my opinion, is problematic because depression seems to already be on a spectrum with bipolar disorder; and I think the relationship between schizophrenia and unipolar depression is harder to quantify. Otherwise, I'm in favor of it, because there is (or can be) so much overlap between the two.

Really good information here - thank you :-)

The Secret Life of a Manic Depressive said...

Which is worse is futile, it's utterly dependent on individual cases. Some studies have shown that bipolar disorder has a worse long term prognosis than schizophrenia and some have shown the opposite. The problem is that people think schizophrenia as the cancer of mental illness. It isn't, it's just the same as any other.

My diagnosis has been questioned twice: in my teenage years, they thought I suffered from schizophrenia, more recently, they've ruminated on schizoaffective. The truth is I just have bipolar disorder with prominent psychosis. I always felt my own case shared more in common with schizophrenia than depression, because in my depressive episodes, I suffer from flat affect, catatonic states and so on, rather than classic depression.

Abysmal Musings said...

Thanks all, and to all who have commented on the stigma question: I think we're all in agreement, but perhaps I could have expressed myself a little less cynically.

Yes, like all things there are worse cases and better cases with all spectrum disorders, but as Seaneen mentioned, it's the way people think about it is the problem.

Stormgazer, all on the same spectrum, or perhaps two spectrums describing a square... difficult to say at the present state of research. Some people seem to be moving towards the idea that unipolar depression that isn't caused by external events is probably part of the bipolar spectrum. (Please don't make me look for references on a sunday night!) In otherwords, there is an emerging 'field of thought' that some unipolar depression is bipolar depression without the ups. That could fit on the one line, conceivably. But heck, let's bring the autism spectrum into the equation, then we've got a cube. Any others? We could get into multi-dimensional space quite quickly if we try hard! :-)

Take care all, David