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Symptoms and Signs of Adult ADHD (Attention Deficit Hyperactivity Disorder in Adults)

Doctor's Notes on Adult ADHD (Attention Deficit Hyperactivity Disorder in Adults)

Adult ADHD (Attention Deficit Hyperactivity Disorder in Adults) is defined as a neurodevelopmental disorder that includes primary problems with inattention and/or activity in adults (there is still some controversy about the definition to include substance use, sleep disorders and others). Signs and symptoms include hyperactivity (inner restlessness, can’t relax, unhappy when inactive), impulsivity (impatient, snap decisions, rapidly changing tasks) and inattention (disorganized, poor time management, misses parts of conversations).

Adult ADHD is thought to be caused by both genetics and life-experience factors that theoretically may trigger brain chemicals like dopamine and norepinephrine to have abnormal levels at different brain locations.

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Medically Reviewed on 3/11/2019

Adult ADHD (Attention Deficit Hyperactivity Disorder in Adults) Symptoms

Symptoms of attention deficit hyperactivity disorder (ADHD) in children and adolescents are predominantly external and easy to observe, such as physical hyperactivity. An exception is predominantly inattentive ADHD, formerly referred to as ADD, which is more common in girls. With age, a decrease in observable symptoms of ADHD seems to occur. Adults with ADHD have a longer delay before refocusing when their attention is misdirected, and they have difficulty switching tasks. The hyperactivity and impulsivity of adult ADHD are often more subtle than those symptoms types in children. For example, while hyperactivity may result in children being fidgety and frequently getting up from sitting, this symptom in adults may involve the adult getting bored easily and being unhappy about having to sit still rather than having to frequently change their position. On neuropsychological tests, these individuals often have trouble with sustained effort, planning, organization, visual tracking, and listening attentively.

ADHD is characterized by a long-term history of inattention, impulsiveness, and variable amounts of hyperactivity. Remember that all of these symptoms are normal human characteristics, so ADHD is not diagnosed solely based on the presence of these normal human behaviors. ADHD is determined by the degree of these behaviors and their interference with important areas of life. People with ADHD have these normal human characteristics to an excessive degree, with a poor ability to easily control them.

The Evolution of ADHD Characteristics From Childhood to Adulthood
CharacteristicChildhood ManifestationAdult Manifestation
HyperactivityCannot sit still
Fidgety, restless
Always on the go
Inner restlessness
Inability to relax
Unhappy/discontent when inactive
ImpulsivityBlurting out
Touching or exploring
Can't stay in line
Temper tantrums or outbursts
Interrupting, impatient
Snap decisions, recklessness
Switching tasks rapidly
Feeling "down" when bored or "up" when excited/stimulated
Cannot finish work
Does not appear to hear
Often forgetful
Disorganization, forgetfulness
Poor time management
Misses parts of conversations

Although some adults with ADHD may not meet the full criteria used to diagnose ADHD in children, they may still experience significant impairment in certain aspects of life. Depending on their professional or domestic situation, these adults may need to deal with more complex abstract issues that can be difficult depending on the severity of their ADHD. Consequently, a given individual's perception of his or her own degree of impairment may vary.

Some characteristics of adult ADHD include the following (remember these are normal human behaviors; ADHD is diagnosed based on the presence and severity of more than one of these characteristics):

  • Persistent motor hyperactivity: A person may feel restless, be unable to relax or settle down, or be discontent unless active.
  • Attention difficulties: Someone may have trouble keeping his or her mind on a conversation. For example, a man or woman may be constantly aware of other things going on around him even when trying to filter them out. Or the individual may have difficulty reading, finishing a task, with focus, or may experience frequent forgetfulness.
  • Affective lability: This means that someone shifts from a normal mood to depression or excitement, and these shifts can be either reactive or spontaneous.
  • Disorganization or inability to complete tasks: An affected person may be disorganized at work, home, or school. One frequently does not complete tasks or switches from one task to another.
  • Short temper with short-lived explosive outbursts: A person may lose control for short times or be easily provoked to anger or constantly irritable, and these problems may interfere with personal relationships.
  • Impulsivity: Impulsiveness may be minor (for example, talking before thinking, interrupting conversation, impatience) or major. Abruptly starting or stopping relationships (for example, multiple marriages, separations), antisocial behavior (for example, shoplifting), and excessive involvement in pleasurable activities without recognizing possible consequences (for example, buying sprees) are examples of major impulsivity. The bottom line is that waiting to do something induces discomfort.
  • Emotional overreaction: Someone may react excessively or inappropriately with depression, confusion, uncertainty, anxiety, or anger to ordinary stresses. These emotional responses interfere with problem-solving abilities.

Other psychiatric conditions, such as a substance-abuse disorder, major affective disorder (like major depression or bipolar disorder), anxiety disorders, schizophrenia or schizoaffective disorder, borderline personality disorder, antisocial personality disorder, and schizophrenia must be ruled out as a cause of the symptoms. Similarly, other medical conditions, including sleep disorders (like obstructive sleep apnea [OSA]; insomnia; sleep deprivation), traumatic brain injuries, cognitive disorders, or epilepsy (seizures) may also cause problems with attention.

Adult ADHD (Attention Deficit Hyperactivity Disorder in Adults) Causes

Rather than having any single cause, attention deficit hyperactivity disorder (ADHD) is thought to be related to both genetic and life-experience factors. ADHD tends to run in families, supporting a genetic component. However, no specific gene(s) have been shown to cause ADHD. Additionally, many people with ADHD may not have a personal family history. Similarly, exposure to various toxins or experiences can increase the risk of having ADHD. Prenatal exposure to tobacco, alcohol, and other drugs of abuse can increase the risk of ADHD. Similarly, low birth weight, traumatic birth, or other early childhood traumas or infections may also increase an individual's risk. However, it is critical to understand that most people with any one of these exposures still will not have ADHD.

Biologically, ADHD is a neurochemical and neuroanatomical disorder, meaning that specific brain chemicals and brain regions are affected. People with ADHD are thought to have several chemicals (still to be determined) in the brain that are not present in the right quantities in the right places at the right times. Both dopamine (DA) and norepinephrine (NE; noradrenaline) are brain chemicals involved in regulating both attention and reward pathways in the brain and are thought to be affected by ADHD. Many of the medications used to effectively treat ADHD alter brain levels of DA and NE, adding support to the hypothesis that ADHD is related to their function.

Neuroimaging research has shown both that children with ADHD show differences in how their brains develop, as well as identifying areas in the adult brain that seem to function differently. Although brain images are helping us to understand these disorders, an MRI or CT scan cannot be used to establish a diagnosis of ADHD.

Risk factors for childhood ADHD are thought to include male gender, but some of that is known to be the result of the symptoms of ADHD potentially seeming less apparent in girls. Since ADHD in adults is equally identified in men and women, gender is not a risk factor for this disorder in adults. Other risk factors for ADHD are thought to include medical or mental health issues in a father, trauma before birth, being the product of unintended pregnancy, and history of head trauma. Being breastfed is thought to be a protective factor against developing ADHD.

ADHD/ADD in Adults Symptoms & Treatments in Pictures Slideshow

ADHD/ADD in Adults Symptoms & Treatments in Pictures Slideshow

Attention deficit hyperactivity disorder is not limited to children -- 30% to 70% of kids with ADHD continue having symptoms when they grow up. In addition, people who were never diagnosed as kids may develop more obvious symptoms in adulthood, causing trouble on the job or in relationships. Many adults don’t realize they have ADHD, leaving them mystified about why their goals seem to slip out of reach.


Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.