Amyotrophic lateral sclerosis may have more in common with other neurodegenerative and psychiatric diseases than previously assumed, a study indicates.
It concluded that those with ALS are also more likely to develop another neurodegenerative or psychiatric disorder. And the reverse is also true: Those with a neurodegenerative disease or a psychiatric condition are at higher risk of developing ALS.
The study, which covered more than 3,600 patients, supports the idea that all neurodegenerative diseases share common ground, according to researchers at Karolinska Institutet in Sweden. The research, “Neurodegenerative and psychiatric diseases among families with amyotrophic lateral sclerosis,” was published in the journal Neurology.
Researchers used several population registers, which in Sweden are quite extensive, to obtain the data for their work. They cross-linked information from a multi-generation register, a patient register, a causes-of-death register, and a migration register to identify 3,648 patients with ALS. The team included 36,480 controls in their study — people without ALS who were matched to patients by age, sex, and county of birth.
The researchers not only looked at the risk of someone with a neurodegenerative disease or psychiatric condition developing ALS, but also how the risk played out in ALS patients’ families. This involved analyzing disease rates among patients’ parents, siblings, and children.
It turned out that the risk of someone with a neurodegenerative or psychiatric condition developing ALS was 49 percent higher than those without these diseases.
While all neurodegenerative conditions were linked to ALS, frontotemporal dementia, Parkinson’s disease, unspecified dementia, and Alzheimer’s were most strongly associated with the development of ALS — in that order.
Among psychiatric conditions, depression, neurotic disorders, and drug dependence or abuse were linked to a higher risk of developing ALS. Neurotic disorders include anxiety disorders and phobias.
Researchers also discovered that those with ALS were twice as likely to develop another neurodegenerative or a psychiatric condition than those without ALS.
The risk of someone developing another neurodegenerative disease or psychiatric disorder was highest in the year before and after an ALS diagnosis, the team said. The second-highest risk occurred two to five years before or after a diagnosis.
In the year before an ALS diagnosis, people were also at higher risk of developing schizophrenia or a stress-related disorder. Stress-related conditions were also commonly diagnosed in the year after an ALS diagnosis, researchers said.
A previous study by the same research team found the same thing for depression. The risk of a depressed person developing ALS within a year was 3 1/2 times greater than in people without depression.
Other researchers have reported an overlap in genes associated with schizophrenia and ALS.
ALS patients’ relatives were also at higher risk of developing another neurodegenerative condition, but the link was only statistically significant for patients’ brothers and sisters. Their children, on the other hand, were at higher risk of developing a psychiatric disorder, both before and after a parent’s ALS diagnosis.