ASSAY METHOD

1 . A method for the identification or monitoring of Parkinson's Disease (PD) in an individual, which method comprises measuring the level of at least one marker selected from the proteins shown in Table 1 in a first sample taken from the individual, wherein if the level of 14-3-3 theta is measured said sample is not taken from the cerebral cortex of the individual.

2 . A method according to claim 1 , which method comprises comparing the level of said at least one marker in said first sample to a control level and:

identifying the individual as having PD if the level of said at least one marker in said first sample is higher than said control level; or

identifying the individual as not having PD if the level of said at least one marker in said first sample is lower than said control level;

and optionally administering a therapeutically effective amount of a treatment agent to an individual identified as having PD by the said method.

3 . A method according to claim 1 , which method comprises comparing the level of said at least one marker in said first sample to the level of said at least one marker in a second sample taken from the same individual at a later time and:

identifying the PD of the individual as worsening if there is a higher level of said at least one marker in said second sample relative to said first sample, or

identifying the PD of the individual as improving if there is a lower level of said at least one marker in said second sample relative to said first sample.

4 . A method according to claim 2 , wherein the control level of said at least one marker is the level of said marker measured in a sample taken from an individual not suffering from Parkinson's disease, wherein if the level of 14-3-3 theta is measured said sample is not taken from the cerebral cortex of the individual.

5 . A method according to claim 1 , in which a level of said at least one marker in a said sample is determined to be higher than a level to which it is compared if it is at least 1.1-fold, 1.2-fold, 1.5-fold, 1.75 fold, 2-fold, 3-fold, 4-fold, 5-fold or 10-fold higher than the level to which it is compared, and a level of said at least one marker in a said sample is determined to be lower than a level to which it is compared if it is at least 1.1-fold, 1.2-fold, 1.5-fold, 1.75 fold, 2-fold, 3-fold, 4-fold, 5-fold or 10-fold lower than the level to which it is compared.

6 . A method according to claim 1 , wherein a said sample comprises a biological fluid selected from blood, serum, urine and cerebrospinal fluid.

7 . A method according to claim 6 , wherein a said sample is a serum sample.

8 . A method according to claim 1 , which method comprises measuring the said at least one marker in exosomes isolated from a said sample.

9 . A method according to claim 8 wherein said exosomes are isolated from said sample by centrifugation or a microfluidic device

10 . A method according to claim 2 , wherein the individual is suspected of having a neurodegenerative disorder which may or may not be PD.

11 . A method according to claim 10 , wherein the neurodegenerative disorder which is not PD is motorneurone disease (MND), Alzheimers Disease (AD), Multisystem atrophy or Fronto-temporal Dementia (FTD).

12 . (canceled)

13 . A method for determining the effect of a treatment agent on the progression of PD, which method comprises monitoring the progression of PD in an individual in accordance with a method as defined in claim 3 , wherein the first sample is taken from the individual prior to the administration of a treatment agent and the second sample is taken from the individual after the administration of a treatment agent.

14 . A method according to claim 13 , further comprising:

if the PD of the individual is identified as worsening, increasing the dose of the treatment agent and/or administering an alternative treatment agent; or

if the PD of the individual is identified as improving, decreasing the dose of the treatment agent and/or administering an alternative treatment agent with a lower risk of adverse side-effects.

15 . A method according to claim 2 or 13 wherein the treatment agent is selected from L-Dopa, an anti-apoptotic, an anti-oxidant, an anti-glutamatergic, a monoamine oxidase B inhibitor, an adenosine antagonist, a dopamine agonist, a mitochondrial stabiliser, a promoter of alpha-synuclein clearance and a trophic factor.

16 . A method according to claim 1 , wherein the at least one marker is selected from Syntenin-1, 14-3-3 theta and phosphoglycerate kinase 1 (PGK1), and is preferably Syntenin-1.

17 . A method for the treatment of PD in an individual, which method comprises administering to the individual a composition comprising microvesicles, wherein said microvesicles contain at least one protein of Table 1, or which method comprises stimulating the endogenous production of said microvesicles.

18 - 19 . (canceled)