Adults with cerebral palsy without intellectual disabilities have a higher risk of developing mental illness, such as anxiety or depression, than adults who do not have cerebral palsy, according to a new study that examined data of thousands of patients from the United Kingdom.

The research paper, “Risk of Depression and Anxiety in Adults With Cerebral Palsy,” was published in JAMA Neurology.

Research has shown that living with a long-term disability is associated with a twofold to threefold increase in the likelihood of being diagnosed as having depression or anxiety, two of the most common mental illnesses in the worldwide population.

Cerebral palsy is a lifelong condition that develops during childhood. It is likely that people with cerebral palsy, as with any individual, experience psychological, social, and medical issues as they age. However, little is known about anxiety and depression in adults with cerebral palsy as the existing research on mental health outcomes of cerebral palsy patients has been primarily studied in children.

Of the existing studies on the occurrence of mental illness in adults with cerebral palsy, many present issues that need to be considered, namely that some of these studies have been cross-sectional — one-off studies with different sample populations — instead of longitudinal — following a sample population and examining it as it ages.

Also, such studies did not account for intellectual disability, a common co-morbidity (presence of one or more other diseases or conditions) of cerebral palsy occurring in a third of the population. This is critical as distress stemming from intellectual disability can mask the diagnosis typically associated with depression and anxiety.

Therefore, there is a gap in the knowledge and understanding of the risk of mental illness in adults with cerebral palsy and how it, specifically, relates to anxiety and depression.

Now, a group of researchers at various institutions, including the University of Surrey and Brunel University London, studied the occurrence of depression and anxiety in adults with cerebral palsy using existing longitudinal primary care data from the United Kingdom.

In addition, they tested if the comorbidity of intellectual disability affected the link between cerebral palsy and the occurrence of depression and anxiety.

Researchers used the Clinical Practice Research Datalink primary care database, a collection of consultation data from consenting general practices throughout the United Kingdom covering nearly 7% of the population with data from 4.4 million people.

The anonymized data was collected from 1987 to 2015, including clinical events, prescriptions, referrals, and hospital admissions. This database has been used by other studies as a representative snapshot of the population of the United Kingdom.

The researchers took data from any patient 18 or older (mean age 33.3 years) who had at least one record of cerebral palsy during the study period as part of the cerebral palsy group and compared them to individuals without cerebral palsy (i.e. age-, sex-, and general practice-matched controls). In all, 1,705 adults with cerebral palsy were compared to a matched group of 5,115 adults without cerebral palsy.

Researchers tested whether intellectual disability comorbidity was linked with the incidence of anxiety and depression in adults with cerebral palsy. For this analysis, the team split the cerebral group into patients with cerebral palsy with no intellectual disability comorbidity and patients with cerebral palsy and intellectual disability.

The researchers found that adults with cerebral palsy had an increased risk of being diagnosed as having depression or anxiety, compared with a matched control group of adults without cerebral palsy. They found that depression and anxiety occurred in 19.6% and 16.2% of adults with cerebral palsy and without intellectual disability compared to 17% and 13.4% in matched controls, respectively. Conversely, the researchers found that cerebral palsy adults with an intellectual disability had a decreased risk of being diagnosed with having depression or anxiety (13.3% and 12.2%, respectively) compared to matched controls (16.6% and 14.3%).

“More needs to be done to understand why those with cerebral palsy have a greater risk of developing depression and anxiety,” lead author Kimberley Smith, Ph.D., said in a press release. “People with cerebral palsy face unique challenges as they age which could be linked to anxiety and depression. 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.”

The researchers suggest that related risk factors that have been shown to be associated with depression and anxiety in the general population may be particularly relevant to adults with cerebral palsy, such as multi-morbidity, increased pain, functional limitations, non-communicable diseases, difficulties with social relationships, and poorer sleep.

In fact, when the team examined work that has been conducted in adults with cerebral palsy, depressive symptoms were associated with fatigue and pain.

“While our evidence suggests an increased risk of developing anxiety and depression in adults with CP compared with adults who do not have CP, it should be noted that there was little difference in absolute risk for developing anxiety or depression over the total follow-up period,” researchers noted.

The team said that more research is needed to understand why adults with cerebral palsy may have a higher risk of depression and anxiety so that the medical community may develop the foundation for mental health interventions in this patient population.

“These findings support the need to consider cerebral palsy as a lifelong condition and to identify and address mental health problems among people with cerebral palsy alongside physical health problems,” said Jennifer Ryan, Ph.D.

“Despite historically being considered a pediatric condition, the majority of people with cerebral palsy live well into adulthood, and many adults with cerebral palsy experience a worsening of impairments, including a decline in mobility. We hope that the findings of the study will help accelerate a response to adults with cerebral palsy who report inadequate provision of coordinated health services worldwide.”