ADHD has had many different names since the early 1900s, many of which reflected the current thinking of the time. Before the disorder was officially recognized by the American Psychiatric Association (APA) as a mental disorder in the mid-1980s, ADHD was called Minimal Brain Damage and Minimal Brain Dysfunction.

Since then, the disorder has been renamed many times in the APA's Diagnostic and Statistic Manual of Mental Disorders (DSM). The first edition of the DSM called it “hyperactivity of childhood.” The second edition, published in 1968, changed the name to “hyperkinetic reaction of children.” In 1980, the third edition of the DSM renamed it “attention deficit disorder with or without hyperactivity.”

The abbreviation ADD is still used interchangeably with ADHD outside the medical community, but technically the name has changed. In 1988, a text revision of the third edition of the DSM revised the name to “attention deficit hyperactivity disorder, or ADHD.” In 1994, the fourth edition of the DSM added a slash, and revised the name to AD/HD. Although the name of the disorder may undergo more changes in the future as research evolves, for now, the most popular term for the disorder is ADHD.

So What's Taking So Long?

Given the dramatic advances in technology, you may be wondering how and why scientists could figure out how to send a man to the moon, but still not understand what causes a biological disorder that affects millions of people.

The easiest response is that the human brain is a complicated labyrinth. Scientists now know that the primary symptom of adult ADHD is an inability to self-regulate, or to control attention, temper, moods, and impulses.

Everything you do is partly the result of your unique brain wiring and partly the result of learned experiences. As an adult with ADHD, you may not be able to fully integrate learned experiences and, as a result, you may be developmentally younger than your peers and may perform at lower levels.

Your Brain and Executive Function

Several areas of your brain are responsible for controlling executive functions, or brain functions you need to control and regulate your behavior. Some scientists believe the root cause of ADHD lies with response inhibition, or the ability to control your impulses, stay focused, and delay immediate gratification. They also believe this core problem negatively impacts the brain's many other executive functions.

Other executive functions affected by a lack of response inhibition are motor control, which includes hand-eye coordination and the ability to control impulsive movements like finger or foot tapping; regulating your emotions; motivation; and planning. With advances in technology, scientists are now able to explore the brain for abnormalities that could result in ADHD. While past research focused almost exclusively on external factors like parental upbringing, environmental causes, and toxic culprits like sugar and lead, research today targets genetic, anatomical, functional, and chemical brain dysfunctions as potential causes of the disorder.

Your Memory and Adult ADHD

Memory is a highly complex process scattered across many parts of your brain. Simply put, your memory is a system of taking in or acquiring information; coding, filing, and storing it; and retrieving it as you need it.

Adults with ADHD don't necessarily have a bad memory so much as a defect in one or more links of the highly complex chain that makes up memory. By understanding how this process works, you can improve or simply bypass those broken links.

Breaks in the Acquisition Chain

For some adults with ADHD, the broken links occur in the process of acquiring memory. How much you acquire is related to your interest or need for the information, your motivation to acquire it, and your ability to process the information. People with ADHD have considerable trouble remembering details that don't seem important, interesting, or relevant. They may tune out information when they aren't motivated to remember it, or when the information seems boring or repetitive. Many adults with ADHD also lack the patience and focus to sort, process, code, and file information so it's easier to retrieve when they need it later.

Breaks in the Storage Chain

For other people with ADHD, the problem is with storing memory. Many adults with ADHD have defective filters, meaning they have trouble screening out unnecessary data. Instead of sorting the necessary data from the unnecessary, they take it all in. The result is information overload, which can short-circuit working memory. Short-term memory, another type of temporary storage, is also highly vulnerable to distraction and lack of focus, both of which are major challenges for adults with ADHD.

Long-term memory is your vault of safe-deposit boxes in which you code and store facts, experiences, knowledge, values, and routines. When you go grocery shopping and see an apple, orange, and banana, your long-term memory retrieves them from a safe-deposit box you've already labeled “fruits.” With knowledge and experience, you cross-reference each fruit to other fruits by association and create even more coded safe-deposit boxes. For instance, “orange” may be filed in a “citrus” safe-deposit box along with grapefruit and lemon and in another safe-deposit box labeled “fruit that grows on trees” along with apples and pears.

Most adults with ADHD are excellent at thinking outside the box, and they also tend to have active imaginations. While creating an endless succession of different safe-deposit boxes for “orange” poses no problem for them, they might be so prone to distraction that they leave an entire grocery cart of fruit sitting in the parking lot.

Breaks in the Access Stage

When you access information from your memory, you either recognize it as familiar or you retrieve information using specific recall. The ability to recall precise information relies on the way you've stored the information. If you've rote-memorized information with no thought to associating or cross-referencing it to other stored information, you may have trouble remembering it because it's not important. Many adults with adult ADHD are so averse to details, organizing, and planning that their memory files are haphazard.

Breaks in Transfer

Transfer is a complex memory process in which you reshuffle pieces of data to form new knowledge. It can include finding a commonality between divergent ideas or combining unrelated pieces of information into a whole new idea. Many adults with ADHD, being highly creative thinkers, excel at combining wildly divergent ideas into new and creative songs, plots, and works of art. They can also combine their knowledge to solve problems in ways that would never occur to people with more orderly or logical minds. It's no surprise that many famous producers, artists, musicians, physicists, mathematicians, and inventors had adult ADHD.