In ALS models, it was shown that receptors, that bind an important messenger substance (glutamate) in the brain, are increased. In this research project, the investigators want to use a specific radioactive substance to find out whether these receptors are more detectable in people with ALS than in healthy people and increase over the course of the disease.

With this study, the investigators want to examine whether receptors (docking points on the surface of a nerve cell) that bind an important messenger substance in the brain (glutamate) are increased in patients with amyotrophic lateral sclerosis (ALS) as the disease progresses. Based on observations from ALS models, the investigators suspect that this increase in receptors contributes to the damage to the nerve cells in ALS.

To image these receptors, the investigators use a specific radioactive substance and imaging combining positron emission tomography (PET), magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI) of the brain and spinal cord.

The investigators will examine healthy people and ALS patients. The reason is that little is known about the receptor, even in healthy people. The investigators also do not know if and when the receptor is increasingly detectable in the course of the ALS disease. Only by comparing diseased and healthy people it can be determined if and when the receptor is built up in ALS patients. The investigators also hope to gain more information, e.g. about the distribution of receptors in the brain of healthy people compared to patients.

Inclusion Criteria:

• Clinically probable, probable laboratory supported, or definite ALS according to the revised version of the El Escorial World Federation of Neurology criteria (EEC) (45)
• Disease duration ≤18 months
• Pre-study ALSFRS-R progression between disease onset and screening of - 0.4 points/month or worse (calculated by ALSFRS -R total score decline form 48 divided by the months since onset of ALS symptoms)
• Upright slow vital capacity (sVC) ≥65 % of normal (best of three measurements)

Exclusion Criteria :

• Previous participation in another clinical study involving trial medication within the preceding 12 weeks
• History or presence of significant psychiatric disease, such as depression, evaluated with the ALS depression questionnaire (ADI-12) ≥ 23 (43) since depression has an impact on mGluR5 expression (44)
• Use of tobacco, including cigarettes, smokeless tobacco, cigars, and pipes; Ex- smoker having quit smoking ≥ 2 years