• If one sibling of a pair of identical twins (who share identical genes) has ADD, the other has 81% chance of having it. This number drops to only 29% for non-identical, or fraternal, twins.
• If one parent has ADD, the child has 60% chance of having it as well. If both parents have ADD, the probability goes up to 85-90%.
• Parents of ADD kids are 24 times as likely to have ADD themselves.

Little wonder that people are carrying out extensive searches to find genetic footprints of ADD. Earlier studies have already implicated specific gene sites, such as HLA (human leukocyte antigen), dopamine transporter gene, and dopamine receptor D₄ gene with ADHD.

The most recent study, published yesterday (June 23) online in Molecular Psychiatry, has identified hundreds of alterations in chunks (or segments) of genes, rather than in specific point sites, that occur more frequently in children with ADHD than in normal children.

The authors compared genomes of 335 ADHD kids and their families with 2000 unrelated non-ADHD kids, and found 222 such altered gene chunks, called “copy number variations” (CNVs), only in ADHD kids. Many of these CNVs have been previously identified with other neuro-developmental disorders such as autism and schizophrenia.

Read the original article for more details.

More importantly, who should decide if someone is mentally disordered? What if our psychiatrist is wrong? Such labeling not only creates self-doubt in the patient’s mind, it also attaches a social stigma that is often hard to dispel.

“Harmful dysfunction”

Some cases are easy to diagnose. If someone shows unusual behavior that can be harmful to himself or others, he clearly needs professional help; for example, patients suffering from major depressive disorders often have suicidal thoughts, and are likely to attempt it if not given timely help.

This example easily fits the notion of “harmful dysfunction” that Dr. Russell Barkley, a renowned psychiatrist and ADHD expert, proposes to describe the criteria for mental disorder. I agree with Dr. Barkley, up to this point.

Is there a “universal” human behavior?

But then he continues (italics are mine for added emphasis),

For there to be a legitimate, valid disorder, there must be hard scientific evidence that there is a failure or a deficiency in some mechanism that is universal in human beings, a physical mechanism like a heart, a liver, a stomach, a brain. But it can also be a mental mechanism such as … behavioral inhibition.

and again,

Mental disorders are failures or serious deficiencies in mental mechanisms that are universal to the design of this species.

I can not disagree more! I do not have to be a psychiatrist to know that unlike a physical mechanism like heartbeat, where even a slight irregularity can cause serious bodily harm, the range of human behavior is just too vast to have a “universal standard”.

Take the lack of behavioral inhibition, or “disinhibition” as Dr. Barkley calls it, which is considered by many as the strongest symptom of ADHD in kids. But each of us, ADHD or not, shows almost a continuous range of behavioral responses, from sublime poise to annoying impulsiveness. Where should we draw the line, and stamp someone (mentally) disordered?

Is ADHD behavior pattern a harmful dysfunction?

I am not at all convinced there is enough evidence to call ADHD behavior even a dysfunction, let alone harmful. I argue instead that it falls within the wide behavioral range of normal people. (Small wonder that the biggest disagreement today about ADHD in kids is on what is a normal behavior.)

You have two choices. One, accept Dr. Barkley’s (and most others’) view of a narrow range of what constitutes permissible normal behavior, determined by his “universal mental mechanism” (which I believe to be flawed). It is then easy to banish all ADHD-related behavioral patterns outside this restricted range, and brand them dysfunctional.

Or, accept my expanded view and broaden your tolerance for normal behavior to include ADHD. If ADHD is normal, by definition it cannot be harmful. That is, I believe ADHD should be taken as a special class within the highly variable human personality (with some unique traits), rather than a clinical disorder.

It is intriguing that while Dr. Barkley talks of universality to make his case for dysfunction, he invokes “cultural context” to argue potential harm from ADHD. In addressing the question “Does ADHD produce harm to the individual?”, he says (italics are mine),

Now that of course is going to be culturally relative because it depends on the demands that the culture makes on that mental mechanism.

In other words, if your culture is made up of happy-go-lucky folks who love fun and games (as some European cultures are), ADHD is probably a blessing. Whereas, if you belong to a culture that is more work and less fun (as is much of today’s western culture), ADHD can harm your life and career prospect.

That is, unlike most physical (and some mental) deficiencies, ADHD with its behavioral oddities can at most cause only long-term harm, and can possibly be even “cured” by a suitable career move that suits your special abilities.

Is ADHD a real disorder?

To wrap up for now, my answer to this question by Dr. Barkley is that ADHD is real alright, a real personality, not a disorder.

In a later post, I will use evolutionary insights to argue further in favor of ADD being a normal trait. Stay tuned.

Still, the diagnosis made a huge impact on me, by throwing a bright spotlight on a significant chunk of my past life that was somewhat in the dark. Today I understand many struggles, and triumphs, of my life and career that remained unexplained before.

I have devoted every spare minute since then researching on ADD, driven partly by the urge to know more about myself, and also to share with you everything that I learn about this global, and modern, scourge. ADDing Up grew out of this ongoing effort.

Early triumph, late struggle

As a school-going kid, my grades suffered early, but improved in high school and kept getting better afterwards. Since then I breezed through all exams with A+ scores, and by the time I completed Masters graduation (in physics), I was well on course to becoming a brilliant career physicist.

This much of my life is easily explained. I always liked physics and math more than anything else, and my effort on a subject was in direct proportion to my interest in it. As school year progressed through Masters, my curriculum became more and more physics-specific, and grades improved accordingly.

But, once I began doctoral studies, as if a switch flipped inside me, and my  career path suddenly turned uphill. Being free from exams, and lacking a strong internal motivation to stay focused in my study, I spent too much time with friends, and less on research. I did eventually complete Ph.D. (in physics), but it was due more to talent than perseverance.

Mismatch of “productivity” and “potential”

Knowing what I could accomplish if tried enough, my productivity (number of research papers I wrote) was well below my potential, or talent. This mismatch of potential and productivity has dogged my career ever since. I also lacked “staying power” on a single subject, and in the decade since Ph.D., moved from physics to, first chemistry, and finally to biology.

Because I never lacked in talent, and had the subject of choice for Ph.D., I did not understand this persistent lack of motivation, until now. Today I know that my problem has a biological origin inside me, and has nothing to do with my surroundings or friends. ADD, which arises from a certain type of brain structure, weakens our ability to sustain focus over long periods of time.

Exam vs. research – different demand on focus

My power of sustained focus was never really tested in school, because I was intelligent enough to excel in exams with little effort, which needed my attention only in short “bursts”. If grades are a measure of productivity in school, mine was evenly matched with my potential back then.

Talent alone, though, is never enough to do productive research over several years, and perseverance – staying focused through life’s many little bumps and bruises – is usually a bigger virtue.

That is why my internal “ADD switch” flipped when I began doctoral research, because I always struggled to keep myself focused through those distractions. It often took me a long time to complete even the routine projects, and productivity dropped as a result. My struggle continues to this day.

Missing early signs may raise adult ADD risk

Because I did not show typical early signs of ADD as a kid, such as consistently poor grades, difficulty with assignments, inattentiveness, hyperactivity or discipline issues, I never looked for an answer inside me when similar problems (like focus issue and poor productivity) showed up later in my life.

Also, people were not much aware of ADD when I was a kid, and “symptoms” like bad grades and indiscipline were usually blamed on poor parenting. On the contrary, good parenting, such as a comfortable home and help with study, can hide many of these symptoms, and the kids would face problems later when they move out and begin living by themselves (as it was with me).

Lack of awareness might have led to missing many of the early signs in our generation, and a rise of adult ADD cases. Today we know lot more about ADD than our parents ever did. Do we know enough? Do we know right? These are the questions I discuss here.

Absolutely. Why? Because,

Evolution never stops.

Our environment is always changing, and so our brain is also evolving, but so slowly (take home message #1) that we cannot see it unless several thousand generations have passed. And recent scientific evidence suggests this too. Our ancestors had to adapt to the altered conditions of ground-based threats, which triggered the brain size growth. How is the environment changing today?

After agriculture began about 12,000 years ago, and particularly the industrial revolution of late 1800s and early 1900s, rapid advances in technology have considerably improved our life style, and made it fast-paced. Today a teenager’s brain processes more information in an hour than our forefathers did in their entire lifetime. Such increased demand on brain efficiency is likely to favor (Evolution point #2) a stronger brain in the foreseeable future.

Does “stronger” mean “bigger”? Posed another way,

Is our brain still getting bigger?

The best answer that I, or anybody else, can give you today is: Not necessarily. Even though we know how our environment has changed in the last few thousands of years, we  still do not understand our brain well enough to know how exactly this change is driving its current evolutionary course.

We all agree, though, that modern human intelligence depends as much on the size of our brain as on its complex internal structure. And so, with each new generation getting smarter, it is possible that our brain is evolving internally, without getting bigger. Experts also seem to divide along these lines on their interpretation of the latest scientific evidence.

A quick peek at our brain:

If you cut open a human brain vertically in the middle, it looks like the picture here (click to enlarge). Our brain  is packed with many internal organs, each connected to the others in intricate arrangements, and each  performs a variety of complex tasks (much of which is still unknown).

For example, Prefrontal cortex (PFC) is the chief executive of our brain, because it is responsible for forethought, planning, impulse control, and decision making. Likewise, Limbic system (LS) is made up of a number of component organs that together govern our emotion, memory and behavior. Not surprisingly, proper functioning of PFC and LS is vital to develop a normal personality. (People with ADD often differ from others in this aspect, as I will talk about in detail elsewhere.)

It sure looks dramatic when we compress the vastness of 3.5 million years – about 110,000 generations – in a single picture, as shown here (click to enlarge). We see that our brain capacity, measured by “cranial volume” (upper part of the skull that houses our brain), has grown more than two-fold during this time.

What could have happened back then that triggered this growth? Or, in the language of Evolution, how did the environment change millions of years ago that favored the “trait” of large brain size?

To make a complex story overly simple, after the hominids decided to come down from treetops (favored hangout of their ancestor – apes) and live on ground, they faced serious danger from large land animals with sharp tooth and claw. Being no match physically, only those with superior alertness and skill – signs of a healthy brain – survived, and passed on this trait to their offsprings. As the younger generations perfected these survival skills, their senses and intelligence continued to improve, and brain got bigger.

Thus, the new threat on survival of hominids favored the trait of a bigger brain, which continued through the next hundreds of thousands of generations, and has now become the 3lb mass of ganglion inside our head.

Next up: Is our brain still evolving?

First, three simple realities.

1. Individuals vary in “traits”, which are heritable.

There is enormous variation in the way each of us look, think and act. Some are taller than others; some are quick-tempered whereas others are poised. These distinctive “traits” – physical, and to some extent, mental – are passed on from one generation to the next (tall parents usually have tall kids).

2. Only “fittest” traits are favored.

Resources are always limited. There is never enough food, shelter or clothing available for all of us to enjoy the same high quality of life. Because individuals vary in traits, only those with traits that are good “fit” for the prevailing environmental conditions have advantage over the others.

3. Environment always changes with time.

Everything about our environments – temperature, humidity, growth/destruction of forests – keeps changing in every passing hour, day, month and year, going back to millions of years. Day-to-day, and even year-to-year, changes are small; but, over many thousands of years, little changes add up to create large shifts in the environment.

These three facts together generate the mechanism of Evolution.

4. Shifting environments favor different traits at different times.

A population has a range of traits available at any given time (point #1), some of which are better fit to one type of environment, and others to a different environment. Because environments are changing continuously (#3), traits that are good fit today will become unfit after a long enough time.

5. Descendants evolve from ancestors by inheriting fittest traits over many generations.

Over thousands of generations (assuming one generation to span 30 years on average, this means a time scale of 30,000 years or longer), less fit traits are slowly replaced by fitter traits in the population. This is because unfit individuals die faster, and more good traits are passed on to succeeding generations. After a long enough time, the evolved descendant population will be different from its ancestor.

As an example, consider the height of the present 20+ US population, which ranges from under 5ft to over 7ft, with a mean height of 5ft 7in (averaged over males and females). Now, imagine a world where they spend entire life standing upright in neck-deep water, which is at 4ft now and rising very slowly. This changing environment will favor tall people, who will in turn have tall kids. After many generations, mean height of the descendants would be larger than the current height.

Take-home messages:

The two key things to remember are:

1. Evolution is a slow process. Accumulation of fitter traits, and removal of unfit traits, occur at such a slow rate that it takes thousands of generations to see any difference.
2. Evolution is never perfect. There is never enough time for the population to get rid of unfit traits entirely. Long before this can happen, the environment will shift again, and what is fit now will be unfit tomorrow. So, our population always has a mixture of fit and unfit traits.

Now, a real example. The picture (click to enlarge) shows how we gradually evolved from ape-like hominids, who were our earliest known human ancestors, over a period of 3.5 million years (about 110,000 generations).

As it turns out, this change in our overall look also coincided with a more profound change in our brain size. This is what we look at next.