CME Author: Vicki Brower
Study Authors: Kimberley J. Smith, Mark D. Peterson, et al.
Target Audience and Goal Statement:
Neurologists, psychiatrists, psychologists, internists, and family medicine specialists
The goal was to determine whether adults with cerebral palsy (CP) have higher rates of depression and anxiety compared with an age-, sex- and practice-matched reference group of adults without CP.
Do adults with CP have similar or higher rates of depression and anxiety than adults without CP?
Study Synopsis and Perspective:
This retrospective, longitudinal cohort study conducted in the U.K. in the primary care setting found that adults with CP had increased risks of depression and anxiety versus the general population. The association between depression and anxiety found in this study was driven by adult CP individuals without intellectual disability (ID), reported Kimberley Smith, PhD, of the University of Surrey in Guildford, England, and colleagues in JAMA Neurology.
In this study, Smith’s group analyzed data from the Clinical Practice Research Datalink primary care database, a collection of consultation data from general practices throughout the U.K. from 1987 to 2015. Using diagnostic codes, the researchers identified 1,705 patients with CP and matched each one to three controls without CP (n=5,115) by age, sex, and practice visited as an indicator of area-level socioeconomic status.
In the CP cohort, the researchers identified 363 patients with comorbid ID and 1,342 patients with no comorbid ID.
The mean age of the sample was about 33, and 46.8% were women. Of note, people with CP saw their physician more often, and had higher frequencies of epilepsy and pain conditions than controls.
Over approximately 6 years of follow-up, researchers found that 18.3% of people with CP had a new event of depression and 15.3% had a new event of anxiety. Compared with the matched reference group, CP patients showed an increased adjusted hazard of depression (HR 1.28, 95% CI 1.09-1.51) and anxiety (HR 1.40, 95%CI 1.21-1.63), after controlling for other chronic conditions and number of general practitioner visits.
When researchers stratified the data, they found that only CP patients without comorbid ID had a higher risk of incident depression (HR 1.44, 95% CI 1.20-1.72) and anxiety (HR 1.55, 95% CI 1.28-1.87) than matched controls. Other research confirmed that these adults have a relatively high prevalence of depression and anxiety. “We add to this by showing that the risk of depression and anxiety is higher only in people with cerebral palsy who do not have comorbid intellectual disability when compared with age-, sex- and practice-matched controls,” Smith said. “Adults with cerebral palsy and comorbid intellectual disability did not actually have a greater risk of depression or anxiety when compared with matched controls.”
“This is the first study that has ever been done looking at the risk of depression and anxiety over time in adults with cerebral palsy,” Smith told MedPage Today. “There is a lack of knowledge about how aging with cerebral palsy affects people, as traditionally it is considered a pediatric condition.” But CP is a lifelong condition, with most children living into adulthood, depending on the severity of the condition, and its associated physical comorbidities, she noted.
Source Reference: JAMA Neurology, Dec. 28, 2018; DOI:10.1001/jamaneurol.2018.4147
Study Highlights: Explanation of Findings
The researchers noted that the reason that individuals with CP had a higher risk of a diagnosis of depression or anxiety than a matched control group of adults without CP in this study could be due to the “many physiological, psychological, social, and health-related risk factors that have been shown to be associated with depression and anxiety in the general population such as multimorbidity, increased pain, functional limitations, noncommunicable diseases, difficulties with social relationships, and poorer sleep.” Other research with adults with CP has found that depressive symptoms are associated with fatigue and pain, they pointed out.
They contextualized the findings by noting that depression and anxiety are two of the most common mental illnesses in the general population, and that “there is substantial evidence that living with a long-term condition or disability is associated with a 2- to 3-fold increase in the likelihood of being diagnosed as having depression or anxiety.”
Other research cited by Smith and colleagues has indicated that 20%-25% of adults with CP have clinically significant levels of depressive symptoms. Another study with 501 adults with CP cared for at a U.S. clinic found that 39% of patients met criteria for an anxiety disorder, and 31% met criteria for major depression.
“There is evidence that as individuals with CP transition into and throughout adulthood, there can be deterioration in physical functioning and a rise in secondary health conditions. The experience of aging with CP is therefore likely to be linked with different psychological, social, and medical issues than those experienced through having CP as a child,” the authors wrote, adding that most research about CP has focused on children, and those results cannot be generalized to adults.
Adults with CP increasingly are living into later adulthood, observed Robert Fortuna, MD, MPH, of the University of Rochester in New York, who has studied the health of people with CP in the U.S. “Health conditions in adults with cerebral palsy and other developmental disabilities frequently go undetected,” Fortuna told MedPage Today. “Depression and anxiety are potentially treatable and treatment may lead to improved quality of life, health, and physical functioning in adults with cerebral palsy.”
It is important to recognize that cerebral palsy represents a broad spectrum of conditions, he added, nothing that “Depending on the underlying cause and level of cognitive function, mood disorders may present differently.”
Smith’s group stated that “the association between depression, anxiety, and CP could be modified by comorbid ID. Approximately one-third of individuals with CP also experience comorbid ID.” This may complicate the diagnosis of depression and anxiety in a CP patient with an ID, they observed.
According to diagnosis codes used in the U.K., this could mean a learning disability, fragile X syndrome, or Down syndrome. Researchers acknowledged the potential difficulty of diagnosing CP patients who have ID with depression and anxiety due to the issue of diagnostic overshadowing, a process whereby health professionals incorrectly assume that physical symptoms are a result of a patient’s mental illness. As a result, the patient with mental illness or ID is inadequately diagnosed and/or treated.
“In other words, the challenging behaviors overshadow the correct diagnosis of mental illness. This could mean that although it might be expected that the incidence of anxiety and depression to be higher in adults with CP, it is also important to account for the presence of ID,” they stated. “Our results also indicate that ID comorbidity should be considered when assessing the mental health of adults with CP.”
The authors issued a caveat regarding their findings that CP patients with ID had similar risk of depression and anxiety to the matched reference group. “We could have observed these results as previous work suggests that diagnostic overshadowing may lead to an underdiagnosis of mental illness among people who have ID because distress can present as challenging behaviors.” General practitioners may not be experienced in diagnosing depression and anxiety in CP patients with ID, they stated.
More work is needed to understand how and why depression and anxiety are entwined with CP, Smith said. “People with cerebral palsy face unique challenges as they age, which could be linked with this increased risk of developing anxiety and depression,” she pointed out. “This study has allowed us to define the issue; the next step will be to better understand why it happens so we can develop targeted mental health interventions for this population.”
Study limitations included its reliance on diagnostic codes to define outcomes. Also, associations may have been underestimated if depression and anxiety were underdiagnosed. In addition, the term CP incorporated heterogeneous etiologies; the researchers could not take into account the severity of gross motor function, communication, fatigue, and other potential differences among patients.
Original story for MedPage Today by Judy George
Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco