What causes ADHD?

While there is still considerable controversy about the specific cause or causes of ADHD, the one tested and demonstrated fact is that ADHD correlates with a chemical imbalance in the brain. PET scans of the brains of ADHD subjects and brains of individuals not subject to ADHD show a pronounced difference in the levels of neurotransmitters such as dopamine. Chemicals which stimulate the production and uptake of these neurotransmitters seem to help many of those who are ADHD.

Quite a few different hypotheses have been advanced about what actually causes ADHD, but the only clear factor that has been reproducibly correlated with it is genetics. Children with a parent, grandparent, or other close relative with ADHD have a higher likelihood of also being ADHD, even if they are not raised by those parents, such as adopted children. Some hypotheses that have been advanced are:

Drug use by the mother or father - if this caused genetic damage or organic damage to the brain, it might make sense. It is also possible that damage done to a foetus by drugs could manifest ADHD-like symptoms without it actually being ADHD. Fetal alcohol syndrome would fall in this category.

Bad diet - this one is exceedingly difficult to investigate since diets are so varied. Hyperactivity related to excess sugar consumption (and consequently an abundance of quick energy for a child) might look like ADHD to an adult trying to deal with the kid, but it would not really be ADHD.

Environmental poisons - like bad diet, this is exceedingly difficult to establish since it is so difficult to identify everything a child or their parent may have been exposed to. Also like drug use, damage done by a poison can manifest symptoms which are similar to ADHD. Lead poisoning, for example, causes brain damage but does not result in all the symptoms of ADHD.

Too much viewing of TV or other video screens - no, I'm not kidding. There are inconclusive studies that suggest that kids who watch large quantities of the flickering images of video screens have their brains trained to respond abnormally to stimuli.

One of the complicating factors in determining the cause or causes of ADHD is that it has a strong behavioral component. Most people who are successfully coping with ADHD have included a large dose of behavior modification in their overall strategy. Since the same outward behavior (lack of attention, lack of responsibility, distractability, etc.) can stem from a lot of other causes than ADHD, other conditions often get conflated with ADHD and muddy the water for researchers trying to identify a cause.

With all these conflicting theories it seems safe to say that physicians do NOT know what causes ADHD. The entries below, which were entered before I started this edit are a good demonstration of the controversy over the causes of ADHD. Some are quite well thought out and informed, others seem rather off-the-wall, but since we still don't really know what causes ADHD, how can we be certain there isn't some truth in some of the wild theories proposed?

In my case I know my parents didn't do drugs and I probably didn't get lead poisoning. I did watch a fair amount of TV, but it usually didn't hold my attention long enough to spend all that much time watching. The one saving grace for me was a rather high level of intelligence that allowed me to pick up on things extremely quickly during the times I actually paid attention. It drove the teachers nuts. I'd daydream for most of the class and then blow away the rest of the class on the tests - unless I had been daydreaming when some key fact was mentioned and I couldn't reason it out for myself.

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ADHD is the imbalance in certain brain chemicals (called neurotransmitters) that are needed for paying attention and controlling behavior. Two of these neurotransmitters are norepinephrine and dopamine. Recent studies are also demonstrating difference between brain activity of people with ADHD, as compared to people without ADHD. People with ADHD have less activity in certain areas of the brain that help you to pay attention. The medications that are used to treat ADHD work by increasing the levels of these neurotransmitters in the brain.

=Proposed Causes of ADD ==
ADD/ADHD may be inherited. Research shows that ADD/ADHD tends to run in families so there are likely to be genetic influences. Children who have ADHD usually have at least one close relative who also has ADHD. And at least one-third of all fathers who had ADHD in their youth have children with ADHD. Even more convincing of a possible genetic link is that when one twin of an identical twin pair has the disorder, the other is likely to have it too.
Here are more answers and opinions from other FAQ Farmers:

• I've encountered four mothers of ADHD children who admitted the use of hallucinogenic drugs before and during pregnancy (cocaine, LSD or "magic mushrooms"). This is not a confirmed cause but is a strong possibility. Lead poison of the fetus could be related to the use of cocaine or hallucinogenics since lead is used in the process of fabrication. Researcher at MCGill University MTL Canada

• Currently I think it's due to refined sugars (basic sugars that get into the blood stream quickly) and fats in the blood (which your body will use instead of sugars and therefore there's a lot of excess sugars in your blood, or fats in general cause you to not think clearly).

• I have ADD and have put lots of thought into what the cause might be and so on. I have also done much research on the subject. And based on observation of not only myself, but of my mother, brother, and even step father I have come up with some quite interesting observations. Though this is not proven here is my theory. First off let me introduce you to some interesting stuff. If you don't already know ATP or adenosine triphosphate is what mitochondria in our body cells produce for the use of energy. The reason I point that out is because in our brain there is a certain area called the V5 area which is the part that we use for motion detection, therefore sight being an important part. Now,... our metabolism is the rate at which we are able to convert energy sources into ATP for use in our cells. So Lets say that your v5 area of the brain had a slow metabolism of ATP. If so the rate at which you processed what you see is going to be slower. and If you had a high metabolism you'd have a faster processing. What would the effect be? well look at it this way, as analogous to a moving picture camera. When the camera takes pictures at high speed and this in turn is played back and projected on a screen, the motion on the screen will appear to run slow. Conversely, if the pictures are taken in a time-lapsed mode (say one or two frames per minute) much like that of some one with a low metabolism, during projection the motion on the screen appears very fast. I believe that some one with ADD such as myself has a high rate of metabolism of ATP in the V5 area. Due to this every thing around us seams much slower and so what may seam hyperactive to one person to that seemingly hyper active person they are acting normally. This makes lots of since to me because I have noticed that when I get frustrated and such I, as do people when they're bored, feel hungry. And by eating something this slows down ones production of ATP so that the food can be digested. Hence a slower metabolism of ATP in the V5 area allowing that persons to not feel so overloaded with all that he or she is perceiving. It's like playing a game or trying to do something on the computer and every thing is going slow, but in this case it's because your to fast. And at a slow pace there is more time between now and then for you to take in information, and get distracted due to being bored. It's like having to sit through life when every thing around you is in slow motion. But if so you might ask why people with ADD go slow on tests, it's simply either due to getting bored or if you have serious ADD maybe it is because the amount of information you are receiving is simply overloading. Which is most likely the cause of boredom your just so mentally exhausted that you have no more mental energy to even enjoy anything. Also a good example I have noticed in myself and many of my friends with ADD is that we seem to watch "to much TV" or we don't work hard enough. This is because our minds are receiving so much information that by the time we are done with work, school or anything that requires thinking we've thought so much that we're tired of thinking and therefore would like to just zone out on some TV or go to sleep, or smoke pot, get drunk, be lazy. So why do we give people with ADD Ritalin, basically speed? That's because Ritalin is not only speed, what speed alone does is give you dopamine which is used in processing information. What having High having of ATP in this area causes is that your having more thoughts and what you need in order to sort out these thoughts is dopamine. IN the brain of one with ADD we have so many thoughts that our vacuum in our brain cells that sucks up dopamine speeds up because we're needing more dopamine for the sorting of thoughts. But the amount of dopamine that we have is equal to that of a normal person so we run out quickly. When we run out we are no longer able to process what we were thinking about so we, seem to "get "distracted" when actually we just are unable to process any more of that thought and just go to other brain cells and process different thought, until we run out of dopamine in that area, hence the distraction, we do reproduce dopamine though so it is possible to return to that thought. So if given more dopamine by Ritalin we are able to finish our thoughts Ritalin though also slows down our vacuum so it actually makes us think slower in the process. The reason for the "dopamine misfiring" as said by doctors. is due to the fact that since we think so much faster our minds try to produce more dopamine faster so when we try to concentrate or focus all the dopamine we have is shot out instantly and then instantly sucked up by our vacuums after which if the vacuum continues to suck hard or we continue to try and focus the dopamine producers can only shoot out a few dopamines, normally your dopamine creation is faster than the ability of your vacuum to inhale it so that you have excess dopamine their when you really have to concentrate, so one with ADD simply Focuses or concentrates to fast for the dopamine producers to have time to build up a dopamine reserve. But if we try to do something slower we're able to do it better because then our dopamine has time to reproduced so that we can stay focused on that thought, however at a slower pace. This is also why those with ADD tend to have high IQs Because of the constant change in thought we result to thought in more areas of our brain and IQ tests tend to cover a wide verity of areas. I'm not saying though that those with ADD are only intelligent due to a lack of dopamine its just it allows them to have a wider span of knowledge if given the meds they often do even better because then they'll do better in the more focused areas of there thought. But IQ test are inaccurate anyways they base your intelligence mostly on knowledge not ability to use what knowledge you do have.

• In most cases, it is caused by an underlying condition that encompasses all of the symptoms of ADD/ADHD. The cause of this ADD/ADHD outbreak is 99% lack of communication between fields of research. Saying otherwise is simply arrogance or an accouter lesson in greed.

• AD/HD is generally inherited and runs in families. About 1 percent of people develop it for other reasons (e.g. toxins introduced to the developing fetus, faulty sugar or food additive metabolism). Although a possible cause, it is unlikely that many people develop the syndrome purely as the result of hallucinogenic drug use by the mother during pregnancy. There is also the possibility that the mother used such substances because of the lack of inhibition which is a symptom of adult AD/HD. In other words, both the child's and the mother's behaviour stem from the same genetic cause. Brain scans of those who suffer from the disorder show abnormal functioning in areas related to the ability to select what stimuli to attend to or ignore. The "racing brain" which some people talk about is not a sign of intelligence, but a sign that the person doesn't know how to monitor, sift and control their thoughts and actions. While some people with AD/HD are very bright, some aren't. We have the full range in our family.

• I think you probably have a range of problems that have add symptoms in your family. now i don't know much, I'm 21 and I've lived my life not knowing what add was or that the fact that i could never sleep right or remember much was because of something outside of my control. i have some facts that i learned about in my pursuit to understand my condition. i have these facts that I've been gathering. 95% of people diagnosed with add are of higher IQ it is assumed that 5% of the population have it. that kind of leads me to believe that it is related to intelligence but maybe the other 5% had another undiagnosed condition holding them back. i don't know from being taught i know from living that i wouldn't be here right now typing this if i couldn't control my thoughts and actions. i just have trouble controlling how quickly they change. the ability to think is how we have all our technology so how could having so many thoughts that we have trouble keeping up with them without help but we don't need medicine to develop into greater things. i guess my main point is that anyone who thinks that the mind racing isn't a sign of intelligence is just jealous that they can't keep up in that department. think about the correlations between creativity and add. we all know that not every person that is creative has add but pretty much all add folk are creative and creativity is how we create. think about how much environment affects everything and the type of environment America is for someone who is more evolved than 95% of the people there. no wonder we can't sleep.

• Personally, I think ADD is caused by the Mother taking cocaine during pregnancy. While I was a little hyper, my middle brother was extremely ADD. And yet the youngest brother was more calm than practically everyone in the entire extended family. The cocaine is a big secret. I figured it out because I remember finding bundles of white powder, mirrors and razor blades as a kid. But I didn't figure it out until I was about 35 or so. My mother is insane. Pure and simple. And while I am very comfortable with the "typical" symptoms of the drug addicts I see now, and recognize them and their behaviors quickly, it is very difficult for me to reinterpret my experiences as a child with my parents as having been raised by two addicts. THEY would never admit it. But I believe I know the truth of it now. My brother was terribly abused his whole life, and the diagnosis of ADD was my Mother's redemption and salvation. Everything from that point became HIS fault (and his "disease") and the diagnosis was the perfect way for my parents (particularly my Mother) to redirect attention away from THEIR disease and their drug addictions. But I think the real deal is that mom was a junkie, and screwed up my brother's body chemistry, and then beat him throughout his entire childhood. I would cut her into little tiny pieces with a hatchet, if I could get away with it.

• I spent my life since i was 16 with some horrible secret that I didn't understand. This is when I had my first part time after school job. I couldn't learn what to do and got sacked. I couldn't even understand or remember what was said to me on the job, so I couldn't learn what to do. I was very pretty, so I always got another job. I was always terrified of being incompetent, and inevitably I lost it. After a dozen or so lost jobs spanning ten years, I deliberately got pregnant. As a single mum on welfare, at least I would have a guaranteed (though small) income for the next 16 years in Australia, and I wouldn't keep having to go through this. I have a 'drop kick' useless brother who is always in trouble with the law over some reasonably minor offence. One day I was visiting his place - to give him money for food and rent once again (he always denied vigorously that he had gambled it away, or spent it on whatever took his fantasy). I was horrified when he announced that he had just tricked me into taking speed. I had two young children to care for. I was devastated, and decided I should sleep over his house until the stuff had gone through my system. I had only ever taken paracetemol before. 45 minutes later I felt wonderful. I drove home. I could read a book and absorb what was on the page. I went back to school. I got good enough grades to gain entry to do a Law degree at one of the best universities. (degree top 2% in this country). I was the only person whose father wasn't a top medical specialist or Judge or politician. I started some house cleaning to get a bit of extra money and for the first time I kept a job. I completed projects for the first time in my life. And my horrible depression disappeared. Unfortunately, I was in my 40s before I found out that I had ADD, or a doctor who would prescribe 'dexamphetamine'. In Australia, ADD is deemed not to exist in adults. but I can assure you with no uncertainty whatsoever, that at least in my case, it is a 'dopamine deficiency' that was the problem.
• I'm 13, and i got ADHD from having hypothroidism. Noone else in my family or any close relatives has ADHD, but a few have hypothroidism. Because of the fact that your thyroid controls how much energy you use to complete certain tasks, it makes sense. I didn't know i had ADHD until i was diagnosed in fourth grade, even though i had been taking random pills to help my impulsiveness since 2nd grade. Then finally, in 5th grade, it clicked. My doctor put me on this medication called Vyvanse. It helped me concentrate so much better, that 2 trimesters later, i was in all of the honors classes! Hopefully i will eventually outgrow it!