Cause(s) of ADD - Genetic vs Nongenetic?

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[The following quote from sarek was taken from Khethil's thread "Distracted"]

sarek;30613 wrote:

Small point of clarification is in order here.
ADD is not caused by environmental or technological factors but is at best exacerbated by them. It has a clearly defined physiological cause and cannot be cured.

Hi sarek.

That comment was a bit of a joke so I wasn't particularly careful with what I said and how I said it, yet I do have a response to your point of clarification.

My understanding of ADD is somewhat limited so I hope you'll correct me (citing sources if you could!) where you think I'm incorrect.

I did not think it was true that ADD "has a clearly defined physiological cause ". Here's a quote from Wikipedia's entry on ADHD[1] that echoes my thoughts on this:

Quote:

A specific cause of ADHD is not known.

(Here is the source Wikipedia cites for this comment: Stimulant medication for the treatment of attention-deficit hyperactivity disorder: evidence-b(i)ased practice? -- Bailly 29 (8): 284 -- Psychiatric Bulletin)

Also, the fact that something has a physiological cause is not mutually exclusive to the fact that something has an environmental cause. Interaction with ones enviromenment causes physiological changes in the body that can ultimately be the source of certain diseases or disorders. For example, UV radiation from the sun is an environmental factor that can cause the physiological effect of getting skin cancer.[2] While it has been confirmed that ADD has physiological causes in that "there is a definite difference in brain functioning between a group of individuals diagnosed with Attention Deficit Disorder and those without it"[3], the sources of those physiological causes must still be determined.

Quote:

The underlying physiological mechanism which causes Attention Deficit Disorder is still not thoroughly understood and remains under scientific study.[3]

The fact that something has only a genetic cause however, IS mutually exclusive from the fact that something has an environmental cause. Perhaps that's even what you meant, as ADHD is generally believed to have "a strong genetic component"[1].

But tests on the dietary impact of certain foods seems to indicate that diet can play a role in some cases.[4] (that would be nongenetic, environmental yet physiological) Also,

Quote:

Twin studies to date have suggested that approximately 9-20 percent of the variance in hyperactive-impulsive-inattentive behavior or ADHD symptoms can be attributed to such nonshared environmental (nongenetic) factors.[4]

(Here is the source Wikipedia cites for this comment: (Levy et al., 1997; Nigg, 2006; Sherman, Iacono et al., 1997; Silberg et al., 1996)

In conclusion, I'd say the fact that ADD has physiological causes shows that it's not just "in people's heads" who claim to have it, but doesn't in and of itself show that environmental causes do not play a role in its causation. That would only be the case if the causes of ADD were shown to be solely genetic. While genetic factors do seem to play an important role in most if not all cases of ADD, it seems there is reason to believe that nongenetic environmental factors can play a role as well.

[1] Attention-deficit hyperactivity disorder - Wikipedia, "Causes" section I use Wikipedia b/c of it's convenience while fully recognizing that it's not necessarily an "authority" on anything, especially something like ADHD. Wikipedia's article on ADHD does reference 130 external sources though, so any claims made there should be sufficiently researchable to determine their validity. However, the article is tagged as having disputable nuetrality and need of consensus, and I recognize and appreciate that fact.
[2] What Causes Skin Cancer?
[3] What Causes the Attention Defficit Disorder:HealthyPlace.com Attention Deficit Disorder, Attention Deficit Hyperactivity Disorder (ADD, ADHD) Community
[4] Attention-deficit hyperactivity disorder - Wikipedia, "Environmental factors" subsection

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@Deftil,

Deftil;30698 wrote:

he fact that something has only a genetic cause however, IS mutually exclusive from the fact that something has an environmental cause.

That's not true unless by "something" you only mean the actual genotype. Well established genetic diseases like sickle cell anemia and cystic fibrosis are greatly modified by nongenetic factors.

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@Aedes,

Aedes;30709 wrote:

That's not true unless by "something" you only mean the actual genotype. Well established genetic diseases like sickle cell anemia and cystic fibrosis are greatly modified by nongenetic factors.

Maybe I misunderstand, but wouldn't that then mean that those diseases do not have only genetic causes? Or if they are only modified by nongenetic factors, then that they aren't causes as such?

Given that the definitions of "genetic causes" and "environmental causes" are understood, and that "only" is put in front of one of them, that statement is meant to be tautological. Something can't only have a genetic cause, yet also have an environmental cause. Something with only a genetic cause can be affected, but not caused, by environmental factors.

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@Deftil,

To be precise, if the genetic predisposition is present AD(H)D will manifest itself. It is not like cancer where additional factors are often necessary for pathogenesis.
There is however a host of environmental and internal factors which determine its severity. That may even lead to failure to properly diagnose it. But that won't mean the symptoms are not there.
Diagnostic criteria can be found in the current psychology manual DSM-IV. And one of those criteria is that it has impaired your life.
Now, if one is for instance highly intelligent to begin with and/or has developed effective coping mechanisms this impairment may not be medically detectable. In that case a diagnosis will not be forthcoming despite the presence of other obvious symptoms.

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@Deftil,

Deftil;30772 wrote:

Maybe I misunderstand, but wouldn't that then mean that those diseases do not have only genetic causes? Or if they are only modified by nongenetic factors, then that they aren't causes as such?

The genetic error is both necessary and sufficient to produce the disease in both cases, simple as that. But the natural course of the disease is quite variable, and external factors are major components. Someone with cystic fibrosis will do a lot worse (i.e. have more rapid decline in lung function) if their lungs become colonized with Burkholderia cepacia or Pseudomonas aeruginosa at 6 months of age than if it happens 2 years later. Someone with sickle cell disease is a lot more likely to have a sickle crisis at high altitude.

In other words, disease pathogenesis is a lot more complicated than a single root cause. People with ADHD, whether there are genetic or environmental factors, are more likely to do well if they're in a nurturing environment at home, if they sit in the front of the classroom, if there is smaller class size, and if they get constant reinforcement of good behaviors and admonition of bad behaviors. This is absolutely central to how we manage kids with ADHD. Medical management happens to produce demonstrable clinical benefit in these kids as well, but it's better to address the situational components too.

Quote:

Something with only a genetic cause can be affected, but not caused, by environmental factors.

That's true and fine, but EVERYTHING is affected by environmental factors -- EVERYTHING. It's just a question of how much.

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@Aedes,

[CENTER]The Cure for ADHD[/CENTER]

The cure for ADHD Attention Deficit Hyperactive Disorder is simply exercise and nothing more. Growing children have an over abundance of energy to grow healthy and strong much like a pony that runs and jumps freely in a pasture or corral. ADHD was created from a society that has changed in such a wrongfully restrictive way, that children are no longer allowed the freedom to run or burn off the excess energy that naturally and so correctly provides for their growth, their strength, or their health.

It was common for my generation to walk too and from school; and once home play outside for hours of unsupervised and uncontrolled sports, fun and games. After dinner it was back outside to burn off any excess before some homework and then off to bed. We were so tired at the end of the day, everyday, that there were no sleep disorders either. There was no ADHD and naturally we slept healthy and grew strong as well.

Today, due to manmade insecurities and a change in family structures, children are driven too and from school, told to sit still and listen or study for most of the day, and then are driven home again. It is to dangerous outside these days they are told, so rather than a neighborhood baseball game, or playing outside of any kind, electronic games and television, or more restrictive day care is all there is. If a child is fortunate enough to play on a sports team they are generally so over-coached or controlled by more controlling adults that being told where to stand still and to listen to the coach has become the sport and not the play.

These childhood restrictions have created a new medical industry, the ADHD pit. The current treatment for ADHD is a pill and some more restrictions or behavior modifications. Drug companies are the leading profiteers, with doctors, pharmacist, schools, teachers, and parents all in collusion. Today we force our children to take amphetamines or speed to take them beyond normal function, a shorter route than depressants to tip them over the equilibrium edge. In this semi-comatose drug induced state we further restrain them with specialized confinements of care. The down side of this industry is the child's health and natural development, and child drug abuse that have led to today's methamphetamine problems. Hello! And the purpose is simply to control what naturally is. We put the children in a box so the parents can make more money. And God forbid if they don't fit or becomes agitated or find it impossible to sit still, a doctor is found, some tests are done, ADHD is diagnosed, and some amphetamines are prescribed.

Imagine that we live in an age where energy is in short supply, yet if our children show any at all, we drug them out of it. For shame what we have done to our children, for shame. If one has trouble with an over-active child, the cure is to find ways to activate them. Exercise, that's the cure, the healthy and right thing to do, and nothing more.

=
MJA

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@MJA,

Exercise is great. So is turning off the TV and reading a book.

I've closely watched many people deal with ADD. Whatever the causes, the condition can be influenced by what the individual choses to do: reading will help reverse the effects of ADD.

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@Deftil,

MJA, I agree with much of what you've written, though I don't agree with the "industrial" element to it. I also don't think it's as simple as a deficiency of exercise. Exercise doesn't cure ADHD, it's simply an outlet for energy. It helps the hyperactivity component much more than the attention defecit component.

ADHD is indeed a real medical syndrome that responds to certain medications and certain nonmedical interventions. If kids still mostly ran around with their friends in the afternoon, didn't have TV or video games, and weren't expected to sit still in school when chronically overtired, then there would be far less clinically manifest ADHD in the world.

There is certainly a genetic component, though, ADHD very much runs in families.

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@Aedes,

Aedes wrote:

There is certainly a genetic component, though, ADHD very much runs in families.

I see and recognize this and accept it on your (and other post's) apparent knowledge; however, I have a hard time accepting it. I really do... I just have this gut-feel that prior to many of the exacerbating factors listed above, that what we now call ADHD was something else, innocuous, that has blossomed into a quantifiable medical condition due - mainly - to environmental factors, lack of parenting, multiple information sources, sedentary lifestyles and so on.

Nope, I've no evidence for this (nor any authority on the matter, to be sure) but for some reason that's how I feel compelled to see it.

Thanks

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@Khethil,

Your feeling is not mutually exclusive with evidence for a genetic basis, so you shouldn't have a contradictory posture about it. Hypertension is genetic too, but it was never a problem until we had access to excessive dietary salt.

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@Aedes,

Aedes wrote:

Your feeling is not mutually exclusive with evidence for a genetic basis, so you shouldn't have a contradictory posture about it. Hypertension is genetic too, but it was never a problem until we had access to excessive dietary salt.

Ah yes, excellent point. Thank you!

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@Aedes,

Could ADHD be passed down through the family by a family's lifestyle and not a family's genes?

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@Deftil,

Yes, but they've done studies of monozygotic (identical) twins raised by different families and found much closer concordance with ADHD (and most other psychiatric diseases) between the twins than between adoptive siblings in the same household.

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@Didymos Thomas,

Didymos Thomas wrote:

Could ADHD be passed down through the family by a family's lifestyle and not a family's genes?

I don't think so because it also occurs in the case of children who are adopted into a non-ADHD household.

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@Khethil,

Khethil wrote:

I see and recognize this and accept it on your (and other post's) apparent knowledge; however, I have a hard time accepting it. I really do... I just have this gut-feel that prior to many of the exacerbating factors listed above, that what we now call ADHD was something else, innocuous, that has blossomed into a quantifiable medical condition due - mainly - to environmental factors, lack of parenting, multiple information sources, sedentary lifestyles and so on.

Nope, I've no evidence for this (nor any authority on the matter, to be sure) but for some reason that's how I feel compelled to see it.

Thanks

You are in fact a lot closer to the truth than you know. In my view the genetic anomaly that gives rise to ADHD may have been some kind of experiment by nature which has apparently not been entirely unsuccesful. Otherwise pressures of survival would have eradicated the gene very quickly.
I came across some a study

In our genes ? PNAS

which could even give an indication as to the reason of the relative frequency of the mutation in populations.
A hunter-gatherer society is in general a much more suitable environment for those with the gene than a farmer society. This position has also been backed by recent studies.
I prefer to see it as a diffference rather than a disorder.

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@Deftil,

It's a disorder insofar as it can greatly impair school performance, learning, professional development, and personal relationships. Not that everyone is equally affected by it, but it can be really devastating in some cases.

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@Aedes,

Aedes;30795 wrote:

The genetic error is both necessary and sufficient to produce the disease in both cases, simple as that. But the natural course of the disease is quite variable, and external factors are major components. Someone with cystic fibrosis will do a lot worse (i.e. have more rapid decline in lung function) if their lungs become colonized with Burkholderia cepacia or Pseudomonas aeruginosa at 6 months of age than if it happens 2 years later. Someone with sickle cell disease is a lot more likely to have a sickle crisis at high altitude.

In other words, disease pathogenesis is a lot more complicated than a single root cause. People with ADHD, whether there are genetic or environmental factors, are more likely to do well if they're in a nurturing environment at home, if they sit in the front of the classroom, if there is smaller class size, and if they get constant reinforcement of good behaviors and admonition of bad behaviors. This is absolutely central to how we manage kids with ADHD. Medical management happens to produce demonstrable clinical benefit in these kids as well, but it's better to address the situational components too.

That's true and fine, but EVERYTHING is affected by environmental factors -- EVERYTHING. It's just a question of how much.

There's been some confusion apparently. I never intended to say or imply anything such as that environmental factors can't affect diseases, disorders, or traits. Indeed, part of the point of this thread is to point out potential environmental causes of ADD.

And again, if something has ONLY genetic CAUSES, then it cannot, by definition, have environmental CAUSES. While it's true that it now appears that many disorders have both genetic and environmental causes, it's also true that some disorders seem to have only genetic causes.

Quote:

A genetic disorder is a disease caused in whole or in part by a "variation" (a different form) or "mutation" (alteration) of a gene.

genome.gov | Frequently Asked Questions About Genetic Disorders

BTW, my statement that

Deftil wrote:

The fact that something has only a genetic cause however, IS mutually exclusive from the fact that something has an environmental cause.

wasn't meant to imply that I think ADD has only genetic causes (as I think is clearly demonstrated by the entire point of the OP) but was made to be a correction to the implication I thought sarek made of a disorder not having environmental causes simply because it has physiological causes.

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@Deftil,

Deftil;31420 wrote:

if something has ONLY genetic CAUSES, then it cannot, by definition, have environmental CAUSES.

You've really misunderstood the point I was making.

Point 1:
Even PURE genetic diseases, in which a single defective gene (like cystic fibrosis) or even a single specific point mutation (like in sickle cell anemia) are causal, environmental factors can play a major role in the CLINICAL manifestations of the disease.

Point 2:
Many diseases that are known to have a "genetic component" do not have a SINGLE genetic cause. Think about cancer or coronary artery disease. There are definite family associations and in some cases genes that have been identified, but environmental factors are unambiguous independent risk factors.

Point 3:
Many hereditary diseases are polygenic, i.e. there are several genetic loci in different genes that can contribute to the onset of the disease. No one is known to be individually responsible.

Point 4:
Most psychiatric diseases, including ADHD, are known to run in families but no single genotype is known to be responsible. There are almost certainly multiple hereditary factors, but no one genetic factor is enough to produce the disease in the absence of other non-genetic risks.

THEREFORE:
ADHD is almost certainly the end product of a certain "critical mass" of both genetic and nongenetic factors -- and these factors are not mutually exclusive.

2 Replies

@Aedes,

Aedes;31481 wrote:

You've really misunderstood the point I was making.

With all due repsect of course, I think that's because you claimed a comment of mine was not true when it in fact is. Your points 1 - 4 are accurate as far as I know, and are completely consistent with the comment in question. It looks to me like we are debating over wording though, as "CLINICAL manifestations" wasn't what I meant by "cause".

Perhaps you thought I was trying to imply that environmental factors don't impact genetic diseases/ disorders? (I wasn't!) As I mentioned in my last post, I was pointing out the implication that just because a disease/ disorder is known to have physiological causes, in no way precludes the possibility that it can be caused by environmental factors. I then made the comment that the fact that a disease/ disorder has only genetic causes is mutually exclusive with the fact that it has environmental causes because I thought this may have been the line of thinking that sarek was initially shooting for.

At any rate, it's become clear to me that we have been disagreeing on wording, not concepts, and that our conclusions in regards to the causes of ADD are the same.

Also something just occurred to me, and I'm quite surprised I didn't think of it earlier. I have a genetic disorder for which I can't really see a way that it's manifestation is affected by environmental factors - color blindness. That is beside the point, but that would seem to make it at least somewhat rare in that regard.

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@Aedes,

Aedes wrote:

You've really misunderstood the point I was making.

Point 1:
Even PURE genetic diseases, in which a single defective gene (like cystic fibrosis) or even a single specific point mutation (like in sickle cell anemia) are causal, environmental factors can play a major role in the CLINICAL manifestations of the disease.

Point 2:
Many diseases that are known to have a "genetic component" do not have a SINGLE genetic cause. Think about cancer or coronary artery disease. There are definite family associations and in some cases genes that have been identified, but environmental factors are unambiguous independent risk factors.

Point 3:
Many hereditary diseases are polygenic, i.e. there are several genetic loci in different genes that can contribute to the onset of the disease. No one is known to be individually responsible.

Point 4:
Most psychiatric diseases, including ADHD, are known to run in families but no single genotype is known to be responsible. There are almost certainly multiple hereditary factors, but no one genetic factor is enough to produce the disease in the absence of other non-genetic risks.

THEREFORE:
ADHD is almost certainly the end product of a certain "critical mass" of both genetic and nongenetic factors -- and these factors are not mutually exclusive.

ADHD will always manifest itself if the genetic factors are present. Point 3 has however to be taken into account. Science has not yet a complete picture here.
Environmental factors do not determine whether ADHD will manifest itself. They can influence the severity of the symptoms though.

In that sense you are partly correct because one of the primary diagnostic criteria is impairment. If the environment helps in mitigating the symptoms so that impairment is not detectable by the medical professionals than officially no diagnosis will be possible.
But in those cases the symptoms of ADHD will still be present. Environmental factors therefore do not serve as an on/off switch for the genetic factors to come into play.

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Cause(s) of ADD - Genetic vs Nongenetic?

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