ALS is a rare, progressing disease

Amyotrophic lateral sclerosis (ALS) is a rare, progressing disease in which motor neurons degenerate or die diminishing the signals that control muscle function.

Around 450–500 people in Finland suffer from ALS, and over 150 new cases are detected every year. The disease affects motor nerves that control muscles. ALS destroys these nerves, which leads to the weakening of voluntary muscles.

The ultimate causes of ALS remain unknown, but in studies researchers have discovered gene mutations causing ALS. The most common genetic error behind ALS, C9ORF72,  was discovered a few years ago.According to current information, ALS has a complex genetic background. Environmental factors may also play a role in the development.

ALS has previously been divided into a form that runs in families and occurs at random, but this division is not accurate, as there are families with only one case of the hereditary form of the disease.

The form of ALS that involves frontotemporal lobar degeneration, or frontotemporal dementia (FTD) is relatively common in Finland. With FTD the patients may retain their memory functions for longer than patients with Alzheimer’s, for example, but they may experience difficulties with language, apathy and personality changes instead.

The disease and its treatment are being studied by many research groups, and Finnish patients’ genetic data has also been included in international research data. In the future, personalised medicine may introduce treatments that focus on individual genetic errors. There is preliminary evidence of the effect of new treatments on certain disease types.

ALS is typically diagnosed when the patient is around 65 years of age. The youngest patients with ALS are under 20 years of age. Its onset cannot be affected, and the disease cannot be prevented. People diagnosed with the illness have generally been previously very healthy.

The progression of the disease varies highly between patients. After being diagnosed with ALS, patients usually live for three to five years. Around 20 per cent live for more than five years, and around 10 per cent live for more than ten years.


ALS is diagnosed based on symptoms, by ruling out other possibilities and an electroneuromyography (ENMG). Genetic research is carried out when the diagnosis is unclear, and an evaluation of the prognosis is needed.


The expert interviewed for the article was neurologist Hannu Laaksovirta from HUS.