Understanding ADHD in Older Adults: An Overlooked Concern

The current Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) requires evidence of symptom onset before age 12 to make a diagnosis of ADHD in adults.

A recently published clinical review questions the appropriateness of this criterion in older adults 50 years old and above. It sets forth several reasons:

• ADHD was first recognized in the DSM in 1968, just over fifty years ago. Anyone over fifty is highly unlikely to have been diagnosed with ADHD in childhood, or even to have symptoms properly noticed.
• It is well-established that memories both fade and change with time. Even among young adults, only about half can recall the age at which specific memories occurred. For older adults, the challenge is much greater, and that means questionnaire answers become unreliable.
• Episodic memory among persons with ADHD is known to be impaired relative to controls, which further limits the reliability of memory, especially over extended periods.

On the other hand, the reason for the early onset criterion is to avoid any confusion with early neurodegenerative diseases such as Alzheimer's or Lewy body dementia, which have overlapping symptoms.

The authors suggest a possible fix:

• For those over fifty, readjust the under-12 criterion to instead demonstrate the longstanding previous existence of ADHD symptoms, without forcing it to include the first eleven years of life. They call for research to determine how many years of previous symptoms would best distinguish ADHD symptoms from normal aging and the onset of dementia.
• Establish a family history of ADHD. Heritability estimates suggest that ADHD occurs in roughly half the parents of people with ADHD, and about 15% of grandparents. That means that for persons over 50, having children and/or grandchildren with ADHD would lend greater weight to self-reported ADHD symptoms.
• Noting that "cognitive functioning rating scales(e.g., the Barkley Deficits in Executive Functioning Scale) have shown to align robustly with ADHD symptoms," they "call for studies investigating the use of these rating scales in older adult samples, and particularly their discriminant validity relative to other late-life disorders affecting cognition."
• This would be accompanied by careful screening for physical or psychiatric comorbidities, to reduce the risk of false positives.

It is unethical, the authors suggest, to deny care to older, presently undiagnosed adults, given the demonstrated poor outcomes associated with untreated ADHD.

The CDC recently reported that ADHD medication use in women ages 15 to 44 increased from 0.9 percent to 4 percent from 2003 to 2015.  The most commonly used medications were formulations of amphetamine or methylphenidate.  

This increase in treatment for ADHD suggests that educational programs such as adhdinadults.com have been effective in teaching clinicians how to identify and treat the disorder.   The 4 percent rate reported by the CDC is encouraging because it is close to what Ron Kessler and colleagues reported as the prevalence of adult ADHD in the population.   CDC correctly points out that little is known about the effects of ADHD medications on pregnancies. Thus, caution is warranted.

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Oei et al.'s review of amphetamines concluded: "There is little evidence of amphetamine-induced neurotoxicity and long-term neurodevelopmental impact, as data is scarce and difficult to extricate from the influence of other factors associated with children living in households where one or more parent uses drugs in terms of poverty and neglect. ... We suggest that exposed children may be at risk of ongoing developmental and behavioral impediment, and recommend that efforts be made to improve early detection of perinatal exposure and to increase the provision of early intervention services for affected children and their families"

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Bolea-Alamanac et al.'s review of methylphenidate effects concluded: "There is a paucity of data regarding the use of methylphenidate in pregnancy and further studies are required. Although the default medical position is to interrupt any non-essential pharmacological treatment during pregnancy and lactation, in ADHD this may present a significant risk. Doctors need to evaluate each case carefully before interrupting treatment." These words of caution should be heeded by clinicians caring for women of reproductive age.

Older adults are at greater risk for cardiovascular disease. Psychostimulants may contribute to that risk through side effects, such as elevation of systolic blood pressure, diastolic blood pressure, and heart rate.

On the other hand, smoking, substance abuse, obesity, and chronic sleep loss - all of which are associated with ADHD - are known to increase cardiovascular risk, and stimulant medications are an effective treatment for ADHD.

So how does this all shake out? A Dutch team of researchers sets out to explore this. Using electronic health records, they compared all 139 patients 55 years and older at PsyQ outpatient clinic, Program Adult ADHD, in The Hague. Because a principal aim of the study was to evaluate the effect of medication on cardiovascular functioning after first medication use, the 26 patients who had previously been prescribed ADHD medication were excluded from the study, leaving a sample size of 113.

The ages of participants ranged from 55 from 79, with a mean of 61. Slightly over half were women. At the outset, 13 percent had elevated systolic and/or diastolic blood pressure, 2 percent had an irregular heart rate, 15 percent had an abnormal electrocardiogram, and 29 percent had some combination of these (a "cardiovascular risk profile"), and 21 percent used antihypertensive medication.

Three out of four participants had at least e comorbid disorder. The most common are sleep disorders, affecting a quarter of participants, and unipolar mood disorders (depressive or more rarely manic episodes, but not both), also affecting a quarter of participants.

Twenty-four patients did not initiate pharmacological treatment. Of the 89 who received ADHD medication, 58 (65%) reported positive effects, and five experienced no effect. Thirty-eight (43%) discontinued ADHD medication while at the clinic due to lack of effect or to side effects. The most commonly reported positive effects were enhanced concentration, more overview, less restlessness, more stable mood, and having more energy. The principal reasons for discontinuing medication were anxiety/depression, cardiovascular complaints, and lack of effect.

Methylphenidate raised heart rate and lowered weight, but had no significant effect on systolic and diastolic blood pressure. Moreover, there was no significant correlation between methylphenidate dosage and any of these variables, nor between methylphenidate users taking hypertensive medication and those not taking such medication. There was no significant difference in systolic or diastolic blood pressure and heart rate before and after the use of methylphenidate among patients with the cardiovascular risk profiles.

Systolic blood pressure rose in ten out of 64 patients, with two experiencing an increase of at least 20 mmHg. It descended in five patients, with three having a decrease of at least 20 mmHg. Diastolic blood pressure rose by at least 10 mmHg in four patients, while dropping at least 10 mmHg in five others.

The authors concluded "that the use of a low dose of ADHD-medication is well tolerated and does not cause clinically significant cardiovascular changes among older adults with ADHD, even among those with an increased cardiovascular risk profile. Furthermore, our older patients experienced significant and clinically relevant improvement of their ADHD symptoms using stimulants, comparable with what is found among the younger age group," and that "the use of methylphenidate may be a relatively safe and effective treatment for older adults with ADHD, under the condition that all somatic complaints and especially cardiovascular parameters are monitored before and during pharmacological treatment."

Yet they cautioned that "due to the observational nature of the study and the lack of a control group, no firm conclusions can be drawn as to the effectiveness of the stimulants used. ... Important factors that were not systematically reported were the presence of other risk factors, such as smoking, substance (ab)use, aspirin use, and level of physical activity. In addition, the response to medication was not systematically measured"