The PET tracer [F18]-FDDNP has a specific affinity for lesions containing tau protein.

The study consists of two phases:

• In the first (cross-sectional) phase it will be assessed the uptake of [18F]-FDDNP in 10 cases with progressive supranuclear palsy (PSP, a tauopathy) en 10 with multi-system atrophy (MSA, a non-tauopathy), along with 20 individuals with Unclassifiable Parkinsonism, as previously defined in a European cohort study.
• In the second (longitudinal) phase it will be prospectively followed the 20 unclassifiable patients (at 6, 12 and 18 months) by means of validated scales and accepted diagnostic criteria in order to try to correlate their eventual clinical diagnosis with baseline PET findings. On this basis, we endeavour to estimate the ability of this technique to detect in vivo underlying tau pathology in subjects initially unclassifiable on clinical grounds.

We hypothesized that:

1. Patients with clinically definite PSP will present an increased uptake in basal ganglia, brainstem and cerebellum.
2. Patients with clinically defined MSA will not present specific uptake.
3. Part of unclassifiable patients with parkinsonism will present a pattern of uptake similar to patients with clinically defined PSP and this part along the clinical follow-up will be meet clinical criteria for diagnose of PSP

Inclusion Criteria:

• The subject is male or female ≥ 40 years old;
• The individual has one of these three conditions:
• probable PSP according to criteria of the National Institute of Neurological Disorders and Stroke (NINDS)
• probable MSA according to criteria of the Second consensus statement on the diagnosis of multiple system atrophy
• unclassifiable parkinsonism according to criteria defined by Katzenschlager et al, 2003:
• Patients with atypical parkinsonism without response to treatment with levodopa and does not meet any of the diagnostic criteria for other known atypical parkinsonism
• Patient given written consent

Exclusion Criteria:

• The subject is diagnosed with Parkinson's Disease and meets the diagnostic criteria United Kingdom Parkinson's Disease Society Brain Bank -The subject is pregnant or breastfeeding;
• The subject has a history of drug abuse or alcohol;
• The subject has a moderate or severe renal function impairment (creatinine serum> 1.5 mg / dL);
• The subject has a moderate or severe hepatic impairment (bilirubin> 2 times the upper limit of normal, transaminases> 3 times the limit top of normal);
• The subject presents structural abnormalities in the basal ganglia or cortical level on MRI or CT;
• The subject has participated in a clinical study with a pharmaceutical product investigation within 30 days prior to screening and / or a radiopharmaceutical minimum period of 5 radioactive half-lives prior to screening;
• Occupational exposure to radiation> 15 milliSievert (mSv) / year
• Use of nonsteroidal antiinflammatory drug (NSAIDs), for some reason, can not be replaced by any other drug 4 weeks before the PET scan;
• The subject has allergy investigational product or any of its components;
• The subject has a clinically severe active disease, with a hope reduced life;
• The subject is claustrophobic / a.