For many years, attention-deficit/hyperactivity disorder (ADHD) was thought of as a disorder of childhood; however, it is now increasingly being recognized as a chronic, lifelong disorder that persists into adulthood in approximately two-thirds of patients.1 While our knowledge about ADHD in adults has increased, most research in this population focused on young or middle-aged adults; less is known about ADHD in older adults. Older adults with ADHD may be newly diagnosed at any point in their lives, or not at all.2 Because ADHD may present differently in older adults than in children or young adults, and because it may impair domains of life in different ways, a closer look at late-life ADHD is needed. This article summarizes the literature on the prevalence, impairment, diagnosis, and treatment of ADHD in adults age >60.
Challenges in determining the prevalence
Few studies have examined the age-specific prevalence of ADHD among older adults.3 Compared with childhood ADHD, adult ADHD is relatively neglected in epidemiological studies, largely due to the absence of well-established, validated diagnostic criteria.1,4 Some experts have noted that DSM-5’s ADHD criteria were designed for diagnosing children, and the children-focused symptom threshold may not be useful for adults because ADHD symptoms decline substantially with age.2 One study evaluating DSM-5 ADHD criteria in young adults (N = 4,000, age 18 to 19) found ADHD was better diagnosed when the required number of clinically relevant inattention and hyperactivity symptoms was reduced from 6 to 5 for each category.5 They also found the DSM-5 age-at-onset criterion of symptoms present before age 12 had a significant effect on ADHD prevalence, reducing the rate from 23.7% (95% CI, 22.38 to 25.02) to 5.4% (95% CI, 13.99 to 16.21).5 This suggests that strict usage of DSM-5 criteria may underestimate the prevalence of ADHD in adults, because ADHD symptoms may not be detected in childhood, or self-reporting of childhood ADHD symptoms in older adults may be unreliable due to aging processes that compromise memory and recall. These findings also indicate that fewer ADHD symptoms are needed to impair functioning in older age.
Determining the prevalence of ADHD among older adults is further complicated by individuals who report symptoms consistent with an ADHD diagnosis despite having never received this diagnosis during childhood.6-8 This may be due to the considerable number of children who meet ADHD criteria but do not get a diagnosis due to limited access to health care.9 Thus, many studies separately analyze the syndromatic (with a childhood onset) and symptomatic (regardless of childhood onset) persistence of ADHD. One epidemiological meta-analysis found the 2020 prevalence of syndromatic ADHD in adults age >60 was 0.77% and the prevalence of symptomatic ADHD was 4.51%, which translates to 7.91 million and 46.36 million affected older adults, respectively.8 Other research has reported higher rates among older adults.6,7,10 The variations among this research may be attributed to the use of different diagnostic tools/criteria, study populations, sampling methods, or DSM versions. Heterogeneity among this research also further supports the idea that the prevalence of ADHD is heavily dependent on how one defines and diagnoses the disorder.
Reasons for late-life ADHD diagnosis
There are many reasons a patient may not be diagnosed with ADHD until they are an older adult.11 In addition to socioeconomic barriers to health care access, members of different ethnic groups exhibit differences in help-seeking behaviors; children may belong to a culture that does not traditionally seek health care even when symptoms are evident.6,9 Therefore, individuals may not receive a diagnosis until adulthood. Some experts have discussed the similarity of ADHD to other neurodevelopmental disorders, such as autism spectrum disorder or social communication disorder, where ADHD symptoms may not manifest until stressors at critical points in life exceed an individual’s capacity to compensate.2
The life transition model contextualizes ADHD as being associated with demand/resource imbalances that come and go throughout life, resulting in variability in the degree of functional impairment ADHD symptoms cause in older adults.2,12 Hypothetically, events in late life—such as the death of a spouse or retirement—can remove essential support structures in the lives of high-functioning individuals with ADHD. As a result, such events surpass these individuals’ ability to cope, resulting in a late-life manifestation of ADHD.
The plausibility of late-onset ADHD
In recent years, many studies identifying ADHD in adults have been published,2,10,12-15 including some that discuss adult ADHD that spontaneously appears without childhood symptoms (ie, late-onset ADHD).2,4,12 Research of late-onset ADHD attracts attention because the data it presents challenge the current rationale that ADHD symptoms should be present before age 12, as defined by DSM-5 criteria. While most reports of late-onset ADHD pertain to younger adults, little evidence exists to reinforce the concept; to date just 1 study has reported cases of late-onset ADHD in older adults (n = 7, age 51 to 59).11 In this study, Sasaki et al11 acknowledged the strong possibility their cases may be late manifestations of long-standing ADHD. Late-onset ADHD is further challenged by findings that 95% of individuals initially diagnosed with late-onset ADHD can be excluded from the diagnosis with further detailed assessment that accounts for co-occurring mental disorders and substance use.16 This suggests false positive cases of late-onset ADHD may be a symptom of narrow clinical assessment that fails to encompass other aspects of a patient’s psychiatric profile, rather than an atypical ADHD presentation.
Comorbidity and psychosocial functioning
ADHD symptoms and diagnosis in older adults are associated with clinically relevant levels of depression and anxiety. The Dutch Longitudinal Aging Study Amsterdam (LASA) examined 1,494 older adults (age 55 to 85) using the Diagnostic Interview for ADHD in Adults version 2.0.10 The 231 individuals identified as having symptoms of ADHD reported clinically relevant levels of depressive and anxiety symptoms. ADHD was significantly associated with these comorbid symptoms.
Continue to: Little is known regarding...