Table 1.

Current International Parkinson and Movement Disorder Society diagnostic criteria for Parkinson's disease; adapted from Postuma RB, Berg D, Stern M et al. MDS clinical diagnostic criteria for Parkinson's disease. Mov Disord 2015;30:1591–601. At least two supportive criteria and no red flags required for a diagnosis of ‘clinically established Parkinson's disease’. Conditions in italics should be considered if the corresponding exclusion criteria or red flags are present.

Parkinsonism defined as: Bradykinesia and rest tremor and/or rigidity
Supportive criteria	Exclusion criteria: PD excluded if present	Red flags
	Alternative diagnosis	Possible alternative diagnosis
Clear and dramatic response to dopaminergic therapy	Cerebellar signs MSA	Wheelchair use within 5 years of onset MSA, PSP
Levodopa-induced dyskinesia	Downward vertical supranuclear gaze palsy or slow downward saccades PSP	Absent progression over 5 years Non-degenerative eg essential tremor, dystonic tremor, drug-induced
Limb rest tremor	Behavioural variant FTD or progressive aphasia within 5 years FTD, PSP	Early severe dysphonia, dysarthria, dysphagia MSA, PSP
Olfactory loss	Lower limb signs only for >3 years VP, NPH	Inspiratory stridor MSA
Abnormal MIBG SPECT	Treatment with dopamine receptor antagonists	Severe autonomic failure within 5 years
	Drug-induced parkinsonism	MSA
	Absence of observable response to high dose levodopa (>600 mg/day) MSA, PSP, CBD	Recurrent falls within 3 years PSP
	Cortical sensory loss, apraxia, progressive aphasia CBD, AD	Disproportionate antecollis (excessive forward neck flexion) or limb contractures within 10 years MSA
	Normal dopaminergic functional imaging (eg dopamine transporter SPECT) Non-degenerative eg essential tremor, dystonic tremor, drug-induced	Absence of any non-motor features after 5 years Non-degenerative Otherwise unexplained pyramidal signs MSA, VP Symmetrical parkinsonism throughout disease course Atypical parkinsonism

AD = Alzheimer's disease; CBD = corticobasal degeneration; FTD = frontotemporal dementia; MIBG = metaiodobenzylguanidine; MSA = multiple system atrophy; NPH = normal pressure hydrocephalus; PD = Parkinson's disease; PSP = progressive supranuclear palsy; SPECT = single-photon emission computed tomography; VP = vascular parkinsonism.