Higher Metabolic Rate May Contribute to ALS Development, Population-based Study Suggests

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by Alice Melão |

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Health conditions that may lead to a faster metabolism, or higher metabolic rate, may contribute to the development of amyotrophic lateral sclerosis (ALS), a large-scale, population-based study suggests.

The study, “Finding diseases associated with amyotrophic lateral sclerosis: a total population-based case–control study,” was published in the journal Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration.

Researchers reviewed clinical records of the National Health Insurance Research Database (NHIRD) of Taiwan to better understand whether ALS is associated with other diseases. The data was collected according to incidence of illnesses diagnosed one, three, five, seven, or nine years before ALS diagnosis.

“Diseases occurring at a time closer to ALS diagnosis may develop because of the protective or detrimental role of ALS,” they wrote.

The NHIRD covers about 99.6% of the Taiwanese population, with information dating back to 1996.

The team focused on the clinical records of 705 patients who were diagnosed with ALS between 2007 and 2013, and compared their information with that of 14,100 non-ALS controls matched according to sex, age, residence, and insurance premiums.

They found a total of 28 prior diseases significantly associated with ALS. Most of the identified diseases only showed a relevant association when they were diagnosed one and three years prior to ALS diagnosis.

Diabetes mellitus, intervertebral disc disorders, and contusions of the face, scalp, and neck except the eyes were among the diseases associated with ALS five years prior to diagnosis.

A total of 17 associations were found to represent a potential ALS risk, mainly symptoms related to nutrition and metabolism and their comorbidities, or coexisting conditions (hypermetabolism — high metabolic rate).  And 11 represented protective factors, including diabetes and its comorbidities (hypometabolism — low metabolic rate).

Overall, ALS patients were found to be less likely to have diabetes mellitus, other disorders of the skin and subcutaneous tissue, ear infections, and gingival and tooth diseases. These conditions were also found to have a direct negative effect on ALS.

“Our results supported the theory that hypometabolic disorders have a beneficial effect on ALS incidence,” the researchers wrote.

Furthermore, they found that contusions of the face, scalp, and neck except the eyes five years before ALS diagnosis led to a 1.5 times increased risk of ALS. In addition, nerve-root and plexus disorders and symptoms concerning nutrition, metabolism, and development were linked to a 1.5 and 2.1 times increased risk three years before ALS diagnosis. Hereditary and idiopathic (of unknown origin) peripheral nerve damage and asthma were associated with a 1.7 and 1.3 times increased risk of having ALS within one year, respectively.

These particular conditions exhibited a direct positive effect on ALS development.

“In this study, hereditary and idiopathic peripheral neuropathy, inflammatory and toxic neuropathy, asthma, and contusion of the face and scalp were significantly associated with ALS but only when occurring 1 year before ALS diagnosis, indicating that these prior diseases may represent misdiagnosis of symptoms, rather than [being the initial cause] of ALS,” the researchers said.

These study findings may help explain why a higher metabolic rate induced by high-intensity sports, a thin physical stature, or a lower body mass index may contribute to the development of ALS.

“Defective energy metabolism may play a role in ALS pathogenesis [disease development],” the researchers concluded.