ANXIETY EARLY IN LIFE
COULD IT LEAD TO PARKINSON DISEASE?
MIAMI BEACH—Individuals who show tendencies toward anxiety and pessimism early in life may be people neurologists should watch for the development of Parkinson disease (PD).
Exactly how personality and psychological traits are related to the movement disorder remains a mystery, but researchers suggested there was a linkage after pouring over decades of medical records stored at the Mayo Clinic in Rochester, MN.
James Bower, MD, Assistant Professor of Neurology at the Mayo Clinic College of Medicine, and his colleagues tracked down thousands of patients who – in the years 1962 to 1965 – completed the standardized psychological instrument known as the Minnesota Multiphasic Personality Inventory (MMPI). They then determined which of those patients have now been diagnosed with either parkinsonism or PD.
“This is the first study to show that people with high levels of an anxious or pessimistic personality are at higher risk for developing PD up to several decades later,” said Dr. Bower, who presented the findings here in April at the AAN Annual Meeting.
MINING THE DATA
Dr. Bower said that previous work hinted that there was a link between anxiety and PD. “At the Mayo Clinic,” he said, “we presented a case control study a few years ago that showed anxiety was associated with later development of Parkinson disease and this association remains significant as long as 20 years before the onset of the motor symptoms of the illness. We were interested in looking further in this.”
Dr. Bower took advantage of the fact that from 1962 to 1965 about 50,000 outpatients at the Mayo Clinic were given the MMPI. The patients were not coming to the clinic for surgery and were not there for psychiatric treatment either, he noted.
Starting with the 50,000 individuals, the researchers first limited the group to be studied to those who lived within a 120-mile radius of the Mayo Clinic.
“We were hopeful that our follow-up 40 years later would be better if we tried locating patients who lived close to the Mayo Clinic, and we hoped that if they did live within a 120-mile radius that they would use the Mayo Clinic as their primary medical care and we would have excess to the records,” Dr. Bower explained.
The researchers also dropped from the study any patient younger than 19 years old, primarily because the MMPI interpretation is markedly different for adults and adolescents. In addition, if a patient was under age 19 that individual would not yet be at the age – in 2004 – at which the signs of Parkinson disease would develop.
Older individuals in the 1960s were also excluded. “We excluded patients that were 70 or older at the time of testing,” said Dr. Bower. The researchers considered that if they were over age 70, it is likely they died shortly after being treated and it would require a proxy – a spouse or a child or a more distant relative – to recall conditions that were several decades past.
“We were also concerned that patients 70 years or older might already have a history of disease or had an increased chance of having had the disease at the time of the testing,” he said.
After the exclusions, the researchers had 7,216 individuals, approximately half of women and men who were tested. “We followed then up starting in 2001. We are presenting the data through December 2004,” Dr. Bower said.
The researchers compared those patients who scored in the top 25 percent on several scales of the MMPI with those in the bottom 75 percent. The MMPI had more than a dozen different scales, but Dr. Bower's team studied four scales: for depression, psychasthenia – the older term for anxious personalities, social introversion, and negativity, which tests for a pessimistic type personality.
The follow-up was done in two ways. “First of all we had an active follow up in which we tried to contact every subject, directly or through a proxy,” he said. “We performed a telephone interview and used a validated reading instrument over the telephone for diagnosing Parkinson disease or parkinsonism. If they screened positive for parkinsonism, they were asked to be examined by one of the seven neurologists or if they did not want to be examined we would ask if we could obtain their medical records for review.”
“In addition, we had a passive follow-up so we had access to records through the Rochester epidemiology project – that's an access we have for all the records of all the providers of Olmstead County.”
HIGHER RISKS FOR PARKINSON DISEASE
From an initial set of 50,000 outpatients, the research team eventually tracked down 4,741 of the patients, and determined that 186 of them had developed parkinsonism, and 128 had frank Parkinson disease.
Among their findings:
- The risk of parkinsonism in people who exhibited anxiety in the 1960s was 1.6 times higher than people who showed no anxious tendencies.
- The risk of PD in people who exhibited anxiety in the 1960s was 1.5 times higher than the normal population.
- The risk of parkinsonism in people who exhibited negativism in the 1960s was 1.4 times normal.
- The risk of PD in people who exhibited negativism in the 1960s was 1.5 times that of normal individuals.
Dr. Bower said the studies do not indicate if anxiety and negativism cause PD or are a marker of people who are predisposed to the disease.
“These studies are important,” said Kari Swarztrauber, MD, Assistant Professor of Neurology at Oregon Health Sciences University in Portland, “because we are on the verge of identifying new products that may be able to control these diseases.”
She said that early identification of these people could lead to earlier diagnosis and treatment. Presently, by the time symptoms are discovered much of the damage in Parkinson disease is irreversible, said Dr. Swarztrauber, a co-moderator of the session at which Dr. Bower presented his data.
EXPLAINING THE ASSOCIATION
Dr. Bower suggested that there were several possible explanations for the association between the personality disorders and Parkinson disease but “we really cannot differentiate at this point whether anxiety is a causative factor of the later development of Parkinson disease.”
Daniel Murman, MD, Professor of Neurosciences at the University of Nebraska School of Medicine in Omaha, said, “It is possible that what we are seeing with anxiety and Parkinson disease are problems that are both related to neurotransmitter abnormalities and that what we are seeing with anxiety is the beginning of Parkinson disease 20 years or 30 years earlier. There is also a possibility that there is a genetic link to both disorders.”
Dr. Murman, co-moderator of the session, said there are numerous hypotheses linking the conditions “and not a lot of answers.” “This will be one of the main topics for discussion at these meetings for the next five years.”
ARTICLE IN BRIEF
- ✓ Investigators reported that – using data from patients at the Mayo Clinic from 1962 to 1965 who took the Minnesota Multiphasic Personality Inventory – 186 of 4,741 patients developed parkinsonism, and 128 had frank Parkinson disease.