One of your older patients comes in for a visit, and you notice that they’ve had trouble recalling things, completing common tasks, and paying attention during conversations. And it’s not the usual kind of forgetfulness that comes with old age or stress. No, their problems with attention, memory, and planning seem to be more in line with those typical of mild cognitive impairment or even dementia. But, you may be surprised to learn that there’s another (often overlooked) disorder that causes these symptoms as well: attention-deficit/hyperactivity disorder (ADHD). 

Although usually associated with school-aged children, some older adults with attention and memory problems can have ADHD. Researchers have shown that symptoms of ADHD can carry over into adulthood for two-thirds of patients who had ADHD as children.

Here’s what all doctors should know about this surprising memory loss culprit:

Prevalence of ADHD in adults

ADHD is also one of the most heritable health disorders, meaning that someone with ADHD may have a parent, grandparent, or sibling with the disorder. It’s a varied neuropsychiatric disorder that is more dimensional than categorical. ADHD is most common in children and teens, with a prevalence of 5%, but adults can have it, too. 

According to the National Institutes of Mental Health, the overall prevalence of ADHD in US adults aged 18-44 years is 4.4%, with a higher prevalence among men (5.4%) than women (3.2%). The lifetime prevalence for ADHD in US adults of the same age range is 8.1%. 

In a systematic review published in Neuropsychiatric Disease and Treatment, researchers suggested that the prevalence of ADHD symptoms declines to 1.0% to 2.8% in the most elderly. It’s not clear why the prevalence is so low in this elder-most population subset, but the authors speculated on a few possible reasons.

1. First, those with ADHD may die younger due to accidents, substance abuse, mood disorders, and so forth.
2. Second, lack of age-related diagnostic criteria may contribute to underdiagnosis.
3. Third, the differential diagnosis for older-age ADHD is long and includes mild cognitive impairment, dementia, other neurodegenerative disorders, polypharmacy, sleep disturbances, chronic pain, and difficulties with vision/hearing. ADHD could, therefore, be mistaken for one of these other conditions.

“Despite the lack of research on ADHD in adults aged ≥ 50 years, and many unanswered questions about prevalence and persistence of ADHD throughout the lifespan, there is reason to believe that ADHD or residual ADHD persists into middle age and late adulthood in a large number of patients,” explained the authors.

They added: “A number of recent studies from different countries using national registers and prescription databases have shown that a growing number of patients aged ≥ 50 years are assessed and treated for ADHD worldwide.”

Memory problems and other symptoms

Young people with ADHD often present with inattention, impulsivity, and hyperactivity. Structural and functional pathology is common, with problems in school and at work, as well as with social situations. Because ADHD symptoms can extend into adulthood for a lot of patients (and more people are living longer), the topic has taken on increased gravitas in recent times. But, there is limited research on the topic, with few case reports. 

What we do know is that adults with ADHD have high rates of depression, anxiety, substance misuse, and dependency, as well as personality disorders and issues with self-esteem. In the elderly, retirement can exacerbate ADHD symptoms, much like how the lack of structure over summer vacation can exacerbate the condition in affected school children. Hyperactivity usually abates in adulthood, but heightened motor activity, fidgeting, impatience, risk taking, and sensation seeking are common—all of which can cause substantial impairment.

In addition, adults with persistent (adult) ADHD may be prone to inattention, poor concentration, forgetfulness, distractibility, disorganization, lack of conscientiousness, irritability, emotional lability, and most importantly, problems with working memory. Working memory refers to the ability to maintain or redirect attention, as well as self-control. These problems start in childhood and can worsen with aging.

Researchers who conducted a survey to determine how well ADHD is identified and addressed in US memory clinics found that ADHD may not be seen or recognised as frequently in memory clinics. They speculated that the reason for such misidentification may be due to that ADHD is less prevalent in later life and symptoms might be misattributed to age-related cognitive decline. 

“Since attention is an important component in memory processes, patients with impaired attention capacity are likely to develop memory deficits. A trained neuropsychologist using a comprehensive neuropsychological battery would likely be able to differentiate between attention and memory difficulties due to ADHD and those due to acquired cognitive dysfunction such as dementia, as the pattern of deficits in ADHD involves a decreased rate of learning while dementia typically involves a rapid rate of forgetting,” wrote the authors. 

“However, the brevity of many memory screening batteries and the overlap in symptoms may result in uncertainty regarding etiology. When geriatric patients present to memory clinics with memory impairments, the presence of ADHD may thus be a confounding variable,” they added.

Treatment

There’s no cure for ADHD. But, certain interventions could help improve working memory. Some researchers have suggested that mental exercises like brain teasers could boost working memory in those with ADHD. Making use of organisational tools—like calendars, alarms, sticky notes, and daily planners—could also help in managing memory issues and other symptoms of ADHD. In addition, behavioral therapies may also work to improve time management, money management, productivity, anxiety, and quality of life. However, there’s one important caveat to these suggestions: Because of the limited research on adults with ADHD, these measures are based on anecdotal reports as well as clinical study results in children and adolescents. 

As far as pharmaceutical therapies go, stimulants like methylphenidate or dextroamphetamine have been shown to be effective in treating ADHD in adults, including the elderly. These treatments are also effective with respect to issues like executive function and working memory. Though, special considerations in older populations include the risk of increased blood pressure/heart rate and arrhythmias in those with coronary artery disease.

“With aging, a series of changes occur that modify the pharmacokinetics and pharmacodynamics of psychotropic medication. This may influence the efficacy, tolerability, and safety of any psychopharmacologic treatment. Pharmacological treatment in older adults should generally follow similar guidelines as with younger patients except that drug dosing and speed of titration should be slower and start lower,” wrote the review authors. An additional word of caution: Older adults may exhibit decreased drug metabolism and increased sensitivity to side effects.

This story is contributed by Naveed Saleh and is a part of our Global Content Initiative, where we feature selected stories from our Global network which we believe would be most useful and informative to our doctor members.