Thread: Do Parasites Induce Suicide?

This article indicates that suicide victims often show the presence of T gondii, a parasite protoctistan organism (with several warm blooded hosts, especially the cat). T gondii can cause cell inflammation which then releases metabolites which can cause inflammation of brain tissues. People with inflammation in the brain are often seen to have committed suicide, presumably after autopsy evidence.

Previous research has found signs of inflammation in the brains of suicide victims and people battling depression, and there also are previous reports linking Toxoplasma gondii to suicide attempts," she said. "In our study we found that if you are positive for the parasite, you are seven times more likely to attempt suicide."

The work by Brundin and colleagues is the first to measure scores on a suicide assessment scale from people infected with the parasite, some of whom had attempted suicide.

The results found those infected with T. gondii scored significantly higher on the scale, indicative of a more severe disease and greater risk for future suicide attempts. However, Brundin stresses the majority of those infected with the parasite will not attempt suicide: "Some individuals may for some reason be more susceptible to develop symptoms," she said.

"Suicide is major health problem," said Brundin, noting the 36,909 deaths in 2009 in America, or one every 14 minutes. "It is estimated 90 percent of people who attempt suicide have a diagnosed psychiatric disorder. If we could identify those people infected with this parasite, it could help us predict who is at a higher risk."

Science Daily

Although this is interesting news and is also interesting science, are the premises strong enough for the conclusion are are they weak enough for other factors to be considered?

Any comments?

Does it cause other symptoms?
Brain inflammation could mess up the part of the brain which produces serotonin, which causes happiness.

I'm not overly impressed, yet. It reminds me of the link between diabetes and blindness - much more strongly evidenced.

The big problem is in talking about risks and prevalence. There are lots of people with diabetes. There are very few people, diabetic or otherwise, who are blind. That is not the same thing as cat ownership. There are many, many more people owning cats, attempted suicide is not all that common, parasite presence in the bodies of those people is even less. Not all brain inflammation is due to toxoplasmosis.

What's not shown in this abstract/extract/report is the relationship between suicide v. cat ownership v. severe depression. Millions of people own cats and need to manage litter trays (the easiest way to contact the parasite but not the only way). How many of these people are depressed? How many have the parasite? How many have attempted suicide? What are the various/ several correlations for all the various combinations? It's not suggested here that the presence of the parasite is more or less common in the target group than in the cat owning population at large. And then we need to get into the SES status of people who do/don't, can/can't manage other parasite infestations in their pets and the further linkage, if any, with attempted/completed suicide.

Interesting. More work needed.

Though it looks like yet another brick in the wall that seems to be building quite strongly that controlling or eliminating any and all kinds of inflammation is a great, population level, strategy for reducing the incidence of heart disease, several cancers, and psychiatric and degenerative diseases of many kinds. Alzheimer's is another target in this strategy many people think.

There seems to be quite a good summary on the Wikipedia page: Toxoplasmosis - Wikipedia, the free encyclopedia

I would think any effect is weak and there is currently too little data, with too many confounding factors, to draw any conclusions.

Originally Posted by adelady

I'm not overly impressed, yet. It reminds me of the link between diabetes and blindness - much more strongly evidenced.

The big problem is in talking about risks and prevalence. There are lots of people with diabetes. There are very few people, diabetic or otherwise, who are blind. That is not the same thing as cat ownership. There are many, many more people owning cats, attempted suicide is not all that common, parasite presence in the bodies of those people is even less. Not all brain inflammation is due to toxoplasmosis.

Agreed, but in the minority of people who are infected, is toxoplasmosis the main or accessory factor? I would hazard a guess that it is an accessory factor at best.

Originally Posted by adelady

What's not shown in this abstract/extract/report is the relationship between suicide v. cat ownership v. severe depression. Millions of people own cats and need to manage litter trays (the easiest way to contact the parasite but not the only way). How many of these people are depressed? How many have the parasite? How many have attempted suicide? What are the various/ several correlations for all the various combinations? It's not suggested here that the presence of the parasite is more or less common in the target group than in the cat owning population at large. And then we need to get into the SES status of people who do/don't, can/can't manage other parasite infestations in their pets and the further linkage, if any, with attempted/completed suicide.

Interesting. More work needed.

Though it looks like yet another brick in the wall that seems to be building quite strongly that controlling or eliminating any and all kinds of inflammation is a great, population level, strategy for reducing the incidence of heart disease, several cancers, and psychiatric and degenerative diseases of many kinds. Alzheimer's is another target in this strategy many people think.

Wow! Good answer. Certainly the prevalence of cat owners vs the prevalence of toxoplasmosis vs toxoplasmosis infected people who have depression would be a nice graph to show in seminars. Yes, most people have answered in the way that I originally guessed, the article is sensational and interesting but the science is certainly inconclusive. It reminds me of the link between diabetes and heart disease - it took me hours to try and find good evidence for the mechanism. Good replies follks!

Toxoplasmosis appears to have a more targeted effect than simple inflammation. It infects both felines and their prey. When it infects a mouse, for example, it clearly changes mouse behavior in a targeted way. The infected mouse becomes less fearful, and is even attracted to cat smells. As a result, the infected mouse is far more likely to die in a cat's jaws. This transfers the pathogen to the primary host, and permits the life cycle to be completed.

Humans frequently get infected also. While no-one is going to suggest it will make someone walk up to a lion in the wild, the infection does appear to change the behavior of the human, including making people more prone to risky behavior. Infected people make great customers for those who offer bungee jumps.

It is not at all unlikely that the reduced fearfulness might remove inhibition to suicide.

I believe there surely are some parasites which can, and perhaps might, produce consideration for suicide. One might be the "Guinea Worm", which grows in length to some three feet or so, inside of one of the victim's larger veins!

Another parasite which strikes me as recently effective also at propagating suicide, is the two-legged variety which drives an individual to extreme acts ill-behavior, after which he commits suicide. Killers of children, for example.

jocular

I don't know about human paracites that induce suicidal behavior but there is a paracite of cattle that does. The other vector of the paracite, its other host, is an ant. The effect of the parcite on teh ant is to make it climb to the top of a blade of grass and stay there all day. This makes it more likely to be swallowed by browsing cattle which in turn spreads the paracyte to another cow. But it is suicidal behavior for teh ant.

The article is a little too vague for my liking. I'd like to see a comparison of suicide rates between people with and without Toxoplasma Gondii. I'd just like to point out that it is estimated a 1/3 of the human population has Toxoplasma Gondii (I've heard of estimates that claim up to 65% - but I am sceptical of number that high). To me this sounds like nothing more than a correlation.

Do obnoxious individuals count as parasites?

Having had a seizure recently and not knowing why, I looked up several of the recent symptoms I have had. There were several possibilities and toxoplasmosis was one possibility of many. I asked my doctor about it and she said it was highly unlikely. The most common cause of toxoplasmosis in humans is from undercooked meat rather than from cats. I'm not saying my doctor knows everything, having had some that tended to ask me what medicine I should take rather than tell me. But as far as the OP is concerned I would think that any kind of brain malfunction could lead to suicide. and anything that alters the brain in any way could lead to suicide, and that includes parasites, drugs, allergies, bacterial infections, genetic defects, viral infections, or extreme emotional trauma.

generally, the cause of suicide is someone deciding they don't want to live anymore.

Originally Posted by jimmythesaint

This article indicates that suicide victims often show the presence of T gondii, a parasite protoctistan organism (with several warm blooded hosts, especially the cat). T gondii can cause cell inflammation which then releases metabolites which can cause inflammation of brain tissues. People with inflammation in the brain are often seen to have committed suicide, presumably after autopsy evidence.

Previous research has found signs of inflammation in the brains of suicide victims and people battling depression, and there also are previous reports linking Toxoplasma gondii to suicide attempts," she said. "In our study we found that if you are positive for the parasite, you are seven times more likely to attempt suicide."

The work by Brundin and colleagues is the first to measure scores on a suicide assessment scale from people infected with the parasite, some of whom had attempted suicide.

The results found those infected with T. gondii scored significantly higher on the scale, indicative of a more severe disease and greater risk for future suicide attempts. However, Brundin stresses the majority of those infected with the parasite will not attempt suicide: "Some individuals may for some reason be more susceptible to develop symptoms," she said.

"Suicide is major health problem," said Brundin, noting the 36,909 deaths in 2009 in America, or one every 14 minutes. "It is estimated 90 percent of people who attempt suicide have a diagnosed psychiatric disorder. If we could identify those people infected with this parasite, it could help us predict who is at a higher risk."

Science Daily

Although this is interesting news and is also interesting science, are the premises strong enough for the conclusion are are they weak enough for other factors to be considered?

Any comments?

Yes:
I have been expecting this result.
The role of "infection" as reasons of behaviour
is in my opinion...seriously underestimated.

Look at stomach ulcers...
How long has the infection
been viewed as misbehaviour?

Do this, do that, and you will get well!
Because you, yourself,
is the cause of your disease!

Originally Posted by Strange

There seems to be quite a good summary on the Wikipedia page: Toxoplasmosis - Wikipedia, the free encyclopedia

I would think any effect is weak and there is currently too little data, with too many confounding factors, to draw any conclusions.

There is a very striking example in biology: A parasite makes the ant climb to the top of straw of grass and there ithe ant gets eaten by a cow eating grass. In the intestines of the cow the parasite lays its eggs and when the eggs come out "the natural way" it infects ants passing by and the circle is closed.

Clearly the parasite is the real and strong reason
behind the ant climbing to the top of the straw...
Its not normal behaviour of a healthy ant.

What can be done to an ant can,
in principle be done to a human.

Originally Posted by Sealeaf

I don't know about human paracites that induce suicidal behavior but there is a paracite of cattle that does. The other vector of the paracite, its other host, is an ant. The effect of the parcite on teh ant is to make it climb to the top of a blade of grass and stay there all day. This makes it more likely to be swallowed by browsing cattle which in turn spreads the paracyte to another cow. But it is suicidal behavior for teh ant.

Correct! But not widely known!

OK sigurdV, I accept that behaviours can be changed in ants. Does this also apply to the millions of cat owners in the world? If so, there is a causative relationship betrween toxoplasmosis and brain aberrations. However, in higher animals I would assume that we can have override mechanisms and that there are also genetic and environmental factors which have a role to play in this situation.

Complications from toxoplasmosis infection in humans can be associated with reduced immune function (e.g. more of a risk in pregnant women and people with AIDS) so the "thing" that causes people with toxoplasmosis to kill themselves, if there really is a correlation, could be whatever caused the immune function to be reduced in the first place, not the toxoplasmosis itself. Correlation does not prove causation.

That was my main point. There is a correlation. And science writers wanted sensational news and toxoplasmosis fitted the bill. However, indeed, correlation does not prove causation and the collection of suitable evidence considering all other possible interfering factors seemed to be ignored in place of the sensational news aspects of the story.

Originally Posted by jimmythesaint

That was my main point. There is a correlation. And science writers wanted sensational news and toxoplasmosis fitted the bill. However, indeed, correlation does not prove causation and the collection of suitable evidence considering all other possible interfering factors seemed to be ignored in place of the sensational news aspects of the story.

You may be one of relatively few people who realize that the news organizations no longer just report what happens. They are entertainers who's main goal is to make money selling publications. Sensationalism replaced reporting the news a very long time ago.

Yes, parasites can be a factor for mental degradation leading to suicide. An example is the fish tapeworm. This parasite enters a human when a parasitic fish is consumed that is not cook properly. As there are no signs in early parasitic infection the parasite in not noticed by the host. This particular bugger depletes the vitamin b-12 from the host. After a few years the symptoms of the host are fatigue and anemia. When trying to diagnose this the doctors often think the lack of energy and fatigue are linked to depression Fish tapeworm infection may lead to vitamin B-12 deficiency and megaloblastic anemia.

How this could lead to suicide is a persons baseline health decompensates to lowering baselines over time causing depression then suicide.

Originally Posted by pineapple007

Yes, parasites can be a factor for mental degradation leading to suicide. An example is the fish tapeworm. This parasite enters a human when a parasitic fish is consumed that is not cook properly. As there are no signs in early parasitic infection the parasite in not noticed by the host. This particular bugger depletes the vitamin b-12 from the host. After a few years the symptoms of the host are fatigue and anemia. When trying to diagnose this the doctors often think the lack of energy and fatigue are linked to depression Fish tapeworm infection may lead to vitamin B-12 deficiency and megaloblastic anemia.How this could lead to suicide is a persons baseline health decompensates to lowering baselines over time causing depression then suicide.

Hopefully, when someone is diagnosed with depression a doctor will do a complete physical and have a complete bloodwork performed to determine if there is a physical cause, but I realise that doesn't always happen.

Originally Posted by jimmythesaint

OK sigurdV, I accept that behaviours can be changed in ants. Does this also apply to the millions of cat owners in the world? If so, there is a causative relationship betrween toxoplasmosis and brain aberrations. However, in higher animals I would assume that we can have override mechanisms and that there are also genetic and environmental factors which have a role to play in this situation.

I also exept that. But I use principles , say Occams Razor as an example,as guiding...ahem ,,,principles

And according to the Paranoid Principle you shouldnt dismiss dangerous possibilities easily.
And according to another principle nothing cant get worse.
So I suggest we look carefully into the possibilities in this case.

It is very hard to diagnose symbiotic parasitic infections because of the timeline involved. If the infection causes immediate problems it is easier to diagnose. Giardia is a parasitic protozoan that has symptoms that are fast and recognizable.

Originally Posted by pineapple007

It is very hard to diagnose symbiotic parasitic infections because of the timeline involved. If the infection causes immediate problems it is easier to diagnose. Giardia is a parasitic protozoan that has symptoms that are fast and recognizable.

I think you can diagnose a B12 deficiency, though.

Originally Posted by Alec Bing

Originally Posted by pineapple007

It is very hard to diagnose symbiotic parasitic infections because of the timeline involved. If the infection causes immediate problems it is easier to diagnose. Giardia is a parasitic protozoan that has symptoms that are fast and recognizable.

I think you can diagnose a B12 deficiency, though.

Only if you test for it.

Originally Posted by pineapple007

Originally Posted by Alec Bing

Originally Posted by pineapple007

It is very hard to diagnose symbiotic parasitic infections because of the timeline involved. If the infection causes immediate problems it is easier to diagnose. Giardia is a parasitic protozoan that has symptoms that are fast and recognizable.

I think you can diagnose a B12 deficiency, though.

Only if you test for it.

Yes, that was my point. If someone presents with depression, a physician should be testing for all possible physical causes, such as hypothyroidism and B12 deficiency, before going ahead and prescribing generic antidepressants and/or recommending psychotherapy.

Originally Posted by Alec Bing

Originally Posted by pineapple007

Originally Posted by Alec Bing

Originally Posted by pineapple007

It is very hard to diagnose symbiotic parasitic infections because of the timeline involved. If the infection causes immediate problems it is easier to diagnose. Giardia is a parasitic protozoan that has symptoms that are fast and recognizable.

I think you can diagnose a B12 deficiency, though.

Only if you test for it.

Yes, that was my point. If someone presents with depression, a physician should be testing for all possible physical causes, such as hypothyroidism and B12 deficiency, before going ahead and prescribing generic antidepressants and/or recommending psychotherapy.

Stomach ulcers were caused by sloppy behaviour... stop stressing and your stomach will heal!

Was the advice... we know now its an infection...
So how many more human conditions are caused by invaders?
What abouT schizofrenia?

Scizophrenia is not a single disease. Bot some kinds appear to respond positively to some antiviral drugs. You may conclude from this what you wish.

Originally Posted by skeptic

Scizophrenia is not a single disease. Bot some kinds appear to respond positively to some antiviral drugs. You may conclude from this what you wish.

That mind is a viral effect?
Well if so then its probably like the case of the mitochondries:

We are invaded!
Thank you very much for THE FACT...I didnt know about it!

Originally Posted by sigurdV

That mind is a viral effect?

No.
What I was alluding to is that some kinds of schizophrenia may be caused by, or influenced by, a virus infection. Only a maybe at this stage.

Originally Posted by skeptic

Originally Posted by sigurdV

That mind is a viral effect?

No.
What I was alluding to is that some kinds of schizophrenia may be caused by,
or influenced by, a virus infection. Only a maybe at this stage.

Yes: An immediate "maybe".
Tongue in cheek, I went for "the limits of maybe":
Am I, my mind, an infection of my body?

Mind/Body Symbiosis?

Perhaps we should search for
Mental "Mitochondria"
in nervous tissue?

Now to the "limit of limits?":
Is life an "infection"
of Universes?

Neither a random event,
nor gods creation?
Juat a Psychotic Reality?

What I was alluding to is that some kinds of schizophrenia may be caused by, or influenced by, a virus infection. Only a maybe at this stage.

Are you talking about the affected individual here? Or to the recent research showing a correlation with influenza of the mother during pregnancy and schizophrenia later in the offspring?

AFAIK, this is still at the found-a-correlation stage. It would be pretty expensive to run a prospective study looking at flu vaccinations for reproductive age women, instances of influenza in both immunised and control subjects during pregnancies, then following up and collecting data on mental health outcomes of the children for the next 25 years.

Adelady

It is simple. There are certain anti-virus drugs. Giving these to certain schizophrenics leads to an amelioration of the symptoms. This suggests that a virus is the cause or an aggravating factor in those kinds of schizophrenia.

As I said, just a maybe, since there are other possible ways those drugs may work. But still very suggestive.

Excellent. That's a great deal better. If you can reduce the numbers of people with overt symptoms with anti-virals, and a further reduction for some/few who respond to anti-inflammatories, that will allow better focus on better treatments for those who don't respond to those simpler measures. (And those drugs give some hope that a smallish(?), hopefully significant, group of sufferers might be able to go drug-free after several months or years of this treatment.)

Originally Posted by adelady

Excellent. That's a great deal better. If you can reduce the numbers of people with overt symptoms with anti-virals, and a further reduction for some/few who respond to anti-inflammatories, that will allow better focus on better treatments for those who don't respond to those simpler measures. (And those drugs give some hope that a smallish(?), hopefully significant, group of sufferers might be able to go drug-free after several months or years of this treatment.)

Perhaps also better anti viral drugs. Curing even more suffering ppl.