psychiatric disorders

A study investigated whether there were significant differences in the incidence of psychiatric disorders among relatives of people with ALS.

Amyotrophic Lateral Sclerosis (ALS) is a progressive neurodegenerative disease affecting the nerve cells in the brain and the spinal cord that are responsible for movement.  As the motor nerves slowly die, individuals with this disease are less and less able to initiate or control muscle movement. ALS negatively affects voluntary functions such as walking, lifting, or talking as well as involuntary functions such as breathing, digestion, or sight.

Similarities between ALS and Psychiatric Disorders

More men than women are affected by ALS and psychiatric disorders. Studies on risk factors of ALS and psychiatric disorders suggest a mixture of genetics and environmental factors. Studies on pathophysiology also reveal similarities.

Research has provided evidence that ALS, bipolar disease, autism, obsessive-compulsive disorder, and schizophrenia can have reduced neural network connectivity. Medications such as riluzole, approved for the treatment of ALS, have also been tried in depression with limited results but were found to be promising in the treatment of schizophrenia and obsessive-compulsive disorder. This data suggests that there may be an association between ALS and psychiatric disorders. As a result, scientists have begun to investigate whether these commonalities may have a genetic basis.

An editorial article published in JAMA Neurology in October 2017 discussed the evidence presented by O’Brien and team of an association between ALS and psychiatric disorders among family members. This study in Ireland was based on 127 patients (58 women and 69 men, with a mean age of 64.2 years) listed in the Irish ALS Register between January 1, 2012, and January 31, 2014.

For a control group, the researchers matched each participant with ALS with a person of the same age and sex from the general population. They collected data from 2116 relatives of patients with ALS and from 1128 relatives of the controls.

Unknown genes may play a role in both ALS and psychiatric disorders

They found that 61.4% of ALS patients reported at least one first- or second-degree relative with a history of schizophrenia, obsessive-compulsive disorder, suicide, depression, alcoholism, or autism compared to just 38.6% of those in the control group. Out of the 29 ALS patients with a strong family history of psychiatric disorders, only 5 (17%) were found to carry a certain genetic mutation. As such, this genetic mutation cannot fully account for the association, suggesting that other, unknown genes may be playing a role in both ALS and psychiatric disorders.

The findings of this study lend credibility to the assertion that ALS can be associated with psychiatric disorders.  Although research based on different populations would need to be conducted, finding specific genetic commonalities may offer insights into new treatment options and prevention strategies.

Written by Debra A. Kellen, PhD

References:

(1) Chuquilin M, Wymer S, Wymer J. Increasing evidence for an association between myotrophic lateral sclerosis and psychiatric disorders. JAMA Neurol 2017; Epub 2017 Oct 16. doi:10.1001/jamaneurol.2017.1920
(2) O’Brien M, Burke T, Heverin M, et al. Clustering of neuropsychiatric disease in first-degree and second-degree relatives of patients with amyotrophic lateral sclerosis. JAMA Neurol 2017; Epub 2017 Oct 16.  doi:10.1001/jamaneurol.2017.2699

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