# What unrelated diseases have an inverse correlation **URL:** \ **Category:** Factual Questions\ **Created:** [July 8, 2015, 3:35pm UTC](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582 "2015-07-08T15:35:31Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Wesley\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wesley_clark/32/20581_2.png) [@Wesley\_Clark](https://boards.straightdope.com/u/Wesley_Clark)\ **Post date:** [July 8, 2015, 3:35pm UTC](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582/1 "2015-07-08T15:35:31Z")
Schizophrenia and rheumatoid arthritis are inversely correlated, having one makes you less likely to have the other, and researching why could lead to therapies for both. Are there other conditions like that where having medical condition A makes you less likely to have condition B? ---
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [July 8, 2015, 3:48pm UTC](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582/2 "2015-07-08T15:48:54Z")
Sickle cell anemia is inversely related to HIV and malaria infections. ---
**Author:** ![Kent\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kent_clark/32/105_2.png) [@Kent\_Clark](https://boards.straightdope.com/u/Kent_Clark)\ **Post date:** [July 8, 2015, 3:49pm UTC](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582/3 "2015-07-08T15:49:28Z")
One of the classic inverse relationships is [sickle cell anemia and malaria.](http://www.cdc.gov/malaria/about/biology/sickle_cell.html) Research suggests an inverse relationship between [some cancers and neurolgical diseases.](http://jonlieffmd.com/blog/inverse-relationship-of-cancer-and-brain-disease) ---
**Author:** ![Surreal](https://avatars.discourse-cdn.com/v4/letter/s/eada6e/32.png) [@Surreal](https://boards.straightdope.com/u/Surreal)\ **Post date:** [July 8, 2015, 5:06pm UTC](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582/4 "2015-07-08T17:06:56Z")
Growth hormone receptor deficiencies such as those found in Laron syndrome have an inverse relationship with cancer and diabetes: [http://stm.sciencemag.org/content/3/70/70ra13.abstract](http://stm.sciencemag.org/content/3/70/70ra13.abstract) ---
**Author:** ![Surreal](https://avatars.discourse-cdn.com/v4/letter/s/eada6e/32.png) [@Surreal](https://boards.straightdope.com/u/Surreal)\ **Post date:** [July 8, 2015, 5:45pm UTC](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582/5 "2015-07-08T17:45:25Z")
Alzheimer’s Disease and cancer: [http://www.medscape.com/viewarticle/760142](http://www.medscape.com/viewarticle/760142) Schizophrenia and Type 1 diabetes: > **[Incidence of schizophrenia in a nationwide cohort of patients with type 1...](https://pubmed.ncbi.nlm.nih.gov/17679634/)** > > The incidence of schizophrenia is decreased in patients with type 1 diabetes. ---
**Author:** ![Inigo\_Montoya](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/inigo_montoya/32/124_2.png) [@Inigo\_Montoya](https://boards.straightdope.com/u/Inigo_Montoya)\ **Post date:** [July 8, 2015, 5:51pm UTC](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582/6 "2015-07-08T17:51:38Z")
[Cowpox and smallpox](https://en.wikipedia.org/wiki/Cowpox), ya? The relationship between which inspired vaccination (the word at least). (This is where I refuse to jest about cows, small things, and autism.) Oh what the hell: Childhood leukemia and Alzheimer’s. I’d be willing to bet. ---
**Author:** ![Shodan](https://avatars.discourse-cdn.com/v4/letter/s/9f8e36/32.png) [@Shodan](https://boards.straightdope.com/u/Shodan)\ **Post date:** [July 8, 2015, 6:38pm UTC](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582/7 "2015-07-08T18:38:55Z")
Any serious childhood illness is going to be inversely correlated to cancer, because cancer is mostly a disease of old age. If you die of diphtheria at age 7, you won’t get cancer at age 70. Regards, Shodan ---
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [July 8, 2015, 6:42pm UTC](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582/8 "2015-07-08T18:42:24Z")
> [@Shodan](#): > > Any serious childhood illness is going to be inversely correlated to cancer, because cancer is mostly a disease of old age. If you die of diphtheria at age 7, you won’t get cancer at age 70. > > Regards, > Shodan Yes and amputation of the foot is going to be inversely correlated with broken bones in the foot, but when we measure disease incidence, we measure it as a fraction of the existing sample size not a theoretical sample size. ---
**Author:** ![dougrb](https://avatars.discourse-cdn.com/v4/letter/d/76d3ee/32.png) [@dougrb](https://boards.straightdope.com/u/dougrb)\ **Post date:** [July 8, 2015, 7:15pm UTC](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582/9 "2015-07-08T19:15:04Z")
Threads like this are why I love the dope! ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [July 8, 2015, 8:33pm UTC](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582/10 "2015-07-08T20:33:39Z")
> [@Shodan](#): > > Any serious childhood illness is going to be inversely correlated to cancer, because cancer is mostly a disease of old age. If you die of diphtheria at age 7, you won’t get cancer at age 70. > > Regards, > Shodan Well in an academic way it would be , but in practice its not inversely correlated since the cancer could not be detected in the children with serious childhood diseases. The correlation can only appear when the cancer appears… ---
**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\ **Post date:** [July 9, 2015, 10:59pm UTC](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582/11 "2015-07-09T22:59:42Z")
You have to be careful when concluding that one disease ‘protects’ against another. Yes, there are clear inverse associations such as sickle cell and malaria. But, it pays to remember that before a disease can be correlated with another, it must first be recognized and then diagnosed. As it turns out, when physicians treat a patient with disease X they seem to disregard the possibility that the patient may also have disease Y. [Here is a reference](http://www.nejm.org/doi/full/10.1056/NEJM199805213382106) that demonstrates physicians’ tendency to ignore second diseases in patients who have already been diagnosed with another. This phenomenon may be attributable, at least in part, to physicians’ heavy reliance on [Occam’s Razor](https://en.wikipedia.org/wiki/Occam%27s_razor) - essentially that the preferred explanation is the simplest (or, phrased in medical terms: it’s best to try to explain a patient’s symptoms by invoking one disease and not several). ---
**Author:** ![Pai325](https://avatars.discourse-cdn.com/v4/letter/p/c68b51/32.png) [@Pai325](https://boards.straightdope.com/u/Pai325)\ **Post date:** [July 10, 2015, 1:58am UTC](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582/12 "2015-07-10T01:58:57Z")
> [@Surreal](#): > > Alzheimer’s Disease and cancer: > > [http://www.medscape.com/viewarticle/760142](http://www.medscape.com/viewarticle/760142) > Schizophrenia and Type 1 diabetes: > > [Incidence of schizophrenia in a nationwide cohort of patients with type 1 diabetes mellitus - PubMed](http://www.ncbi.nlm.nih.gov/pubmed/17679634) Finally! An upside to my cancer! ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [July 10, 2015, 11:44am UTC](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582/13 "2015-07-10T11:44:37Z")
Note that it’s _not_ sickle cell, the disease, that inversely correlates with malaria, it’s having the _sickle cell genetic trait_. Sickle cell disease, itself, [makes one more vulnerable to malaria](https://en.wikipedia.org/wiki/Sickle-cell_disease#Malaria_chemoprophylaxis). ---
**Author:** ![ZurBob](https://avatars.discourse-cdn.com/v4/letter/z/71e660/32.png) [@ZurBob](https://boards.straightdope.com/u/ZurBob)\ **Post date:** [July 10, 2015, 12:55pm UTC](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582/14 "2015-07-10T12:55:32Z")
> [@Wesley\_Clark](#): > > Are there other conditions like that where having medical condition A makes you less likely to have condition B? Hemochromatosis VS the (black/bubonic) plague. [http://membercentral.aaas.org/blogs/scientia/hemochromatosis-and-bubonic-plague](http://membercentral.aaas.org/blogs/scientia/hemochromatosis-and-bubonic-plague) ---
**Author:** ![SpyOne](https://avatars.discourse-cdn.com/v4/letter/s/82dd89/32.png) [@SpyOne](https://boards.straightdope.com/u/SpyOne)\ **Post date:** [July 10, 2015, 2:43pm UTC](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582/15 "2015-07-10T14:43:58Z")
A family friend related that his doctor told him that being allergic to wheat also means your body can’t make the bad kind of cholesterol. “No more toast with breakfast, but all the bacon I want” he said. ---
**Author:** ![Blue\_Blistering\_Barnacle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/blue_blistering_barnacle/32/3386_2.png) [@Blue\_Blistering\_Barnacle](https://boards.straightdope.com/u/Blue_Blistering_Barnacle)\ **Post date:** [July 10, 2015, 5:03pm UTC](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582/16 "2015-07-10T17:03:45Z")
> [@KarlGauss](#): > > You have to be careful when concluding that one disease ‘protects’ against another. Yes, there are clear inverse associations such as sickle cell and malaria. But, it pays to remember that before a disease can be correlated with another, it must first be recognized and then diagnosed. As it turns out, when physicians treat a patient with disease X they seem to disregard the possibility that the patient may also have disease Y. > > [Here is a reference](http://www.nejm.org/doi/full/10.1056/NEJM199805213382106) that demonstrates physicians’ tendency to ignore second diseases in patients who have already been diagnosed with another. > > This phenomenon may be attributable, at least in part, to physicians’ heavy reliance on [Occam’s Razor](https://en.wikipedia.org/wiki/Occam%27s_razor) - essentially that the preferred explanation is the simplest (or, phrased in medical terms: it’s best to try to explain a patient’s symptoms by invoking one disease and not several). There are components of “satisfaction of search”, (over?)use of Occam’s Razor, and simply very focused problem oriented treatment. Problem oriented treatment sometimes gets a bad rap, but it’s not always a good thing to look under every rock to see what crawls out. ---
**Author:** ![Tired\_and\_Cranky](https://avatars.discourse-cdn.com/v4/letter/t/a87d85/32.png) [@Tired\_and\_Cranky](https://boards.straightdope.com/u/Tired_and_Cranky)\ **Post date:** [July 10, 2015, 5:15pm UTC](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582/17 "2015-07-10T17:15:08Z")
> [@Surreal](#): > > Schizophrenia and Type 1 diabetes: > > [Incidence of schizophrenia in a nationwide cohort of patients with type 1 diabetes mellitus - PubMed](http://www.ncbi.nlm.nih.gov/pubmed/17679634) Plus the OP noted that rheumatoid arthritis and schizophrenia are negatively correlated. Both RA and type 1 diabetes are autoimmune disorders. I wonder if there is some broader generalization that autoimmune disorders are negatively correlated with schizophrenia. And if so, I’d wonder why. ---
**Author:** ![leahcim](https://avatars.discourse-cdn.com/v4/letter/l/b4bc9f/32.png) [@leahcim](https://boards.straightdope.com/u/leahcim)\ **Post date:** [July 10, 2015, 6:01pm UTC](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582/18 "2015-07-10T18:01:31Z")
> [@Shodan](#): > > Any serious childhood illness is going to be inversely correlated to cancer, because cancer is mostly a disease of old age. If you die of diphtheria at age 7, you won’t get cancer at age 70. By the same token, having testicular cancer makes it very unlikely that you will subsequently develop ovarian cancer and vice-versa. ---
**Author:** ![Blue\_Blistering\_Barnacle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/blue_blistering_barnacle/32/3386_2.png) [@Blue\_Blistering\_Barnacle](https://boards.straightdope.com/u/Blue_Blistering_Barnacle)\ **Post date:** [July 10, 2015, 6:27pm UTC](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582/19 "2015-07-10T18:27:12Z")
> [@Tired\_and\_Cranky](#): > > Plus the OP noted that rheumatoid arthritis and schizophrenia are negatively correlated. Both RA and type 1 diabetes are autoimmune disorders. I wonder if there is some broader generalization that autoimmune disorders are negatively correlated with schizophrenia. And if so, I’d wonder why. I wonder if sex ratios are taken into account? Females are more likely to get rheumatoid arthritis (and many other autoimmune disorders). Males are more likely to get schizophrenia. This could cause an apparent inverse correlation. ---
**Author:** ![Blue\_Blistering\_Barnacle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/blue_blistering_barnacle/32/3386_2.png) [@Blue\_Blistering\_Barnacle](https://boards.straightdope.com/u/Blue_Blistering_Barnacle)\ **Post date:** [July 10, 2015, 6:50pm UTC](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582/20 "2015-07-10T18:50:45Z")
Type I diabetes and schizophrenia inverse correlation would not be due simply to sex ratios. Type I diabetes has nearly equal M:F ratio in childhood, and more males in young adult. [Next page](https://boards.straightdope.com/t/what-unrelated-diseases-have-an-inverse-correlation/724582.md?page=2)