, new research suggests.
In a longitudinal online study, among patients with Parkinson’s disease who had a history of head injury, motor impairment developed 25% faster and cognitive impairment developed 45% faster than among those without such a history.
In addition, severe head injuries were associated with an even more rapid onset of impairment. The results give weight to the idea that “it’s head injuries themselves” prior to the development of Parkinson’s disease that might exacerbate motor and cognitive symptoms, said study investigator Ethan Brown, MD, assistant professor, Weill Institute of Neurosciences, department of neurology, University of California, San Francisco.
The findings emphasize the importance of “doing everything we can” to prevent falls and head injuries for patients with Parkinson’s disease, Dr. Brown said.
The findings were presented at the International Congress of Parkinson’s Disease and Movement Disorders.
Reverse causality concerns
Head injury is a risk factor for Parkinson’s disease, but its relationship to Parkinson’s disease progression is not well established. “There has always been this concern in Parkinson’s disease that maybe it’s problems with motor impairment that lead to head injuries, so reverse causality is an issue,” said Dr. Brown. “We wanted to look at whether risk factors we know relate to the development of Parkinson’s disease can also have a bearing on its progression,” he added.
The analysis was part of the online Fox Insight study that is evaluating motor and nonmotor symptoms in individuals with and those without Parkinson’s disease. The study included participants who had completed questionnaires on such things as head trauma.
The study included 1,065 patients (47% women; mean age, 63 years) with Parkinson’s disease who reported having had a head injury at least 5 years prior to their diagnosis. Among the participants, the mean duration of Parkinson’s disease was 7.5 years.
The investigators employed a 5-year lag time in their study to exclude head injuries caused by early motor dysfunction, they noted. “We wanted to look at people who had these head injuries we think might be part of the cause of Parkinson’s disease as opposed to a result of them,” Dr. Brown said.
In this head injury group, 51% had received one head injury, 28% had received two injuries, and 22% had received more than two injuries.
The study also included 1,457 participants (56% women; mean age, 65 years) with Parkinson’s disease who had not had a head injury prior to their diagnosis. Of these patients, the mean time with a Parkinson’s disease diagnosis was 8 years.
Dr. Brown noted that the age and sex distribution of the study group was “probably representative” of the general Parkinson’s disease population. However, because the participants had to be able to go online and complete questionnaires, it is unlikely that, among these patients, Parkinson’s disease was far advanced, he said.
The investigators adjusted for age, sex, years of education, and Parkinson’s disease duration.