Biomarkers in Neural Disorders

Parkinson's disease (PD), a devastating age-related disease that is clinically defined by its
effects on the motor system, afflicts more than six million people worldwide, imposing
enormous burdens on patients, relatives, caretakers, and society in general. Diagnostic
errors are common, particularly as symptoms first arise. The most common misdiagnoses are
Alzheimer's disease (AD), essential tremor, and vascular pseudo-Parkinson's Disease. An
accurate diagnosis is typically made at a later stage of the disease when marked and
irreversible damage has occurred within the motor control system of the brain. Sensitive and
specific biomarkers of the early stages of PD are urgently needed. Identification of such
markers is critical for the development and assessment of medications and other interventions
designed to eliminate or reduce the gradual and irreversible decline of neurons involved in
the disorder. This study seeks to establish the sensitivity and specificity of what appears
to be a unique brainstem biomarker of PD - an electrically induced trigeminal nerve blink
reflex response - in differentiation of early stage PD from normal controls and such
neurodegenerative diseases as early stage AD, progressive supranuclear palsy (PSP), and
diffuse Lewy Body disease (DLBD). This study will additionally compare the biomarker to
olfactory test results.

Inclusion Criteria:

- The Parkinson's disease (PD) patients will be Hoehn and Yahr stage 2 or less with a
history of motor symptoms less than two years.

- The Alzheimer's disease (AD) patients will meet the 2011 National Institute on
Aging-Alzheimer's Association and the 1984 National Institute for Neurological and
Communicative Disorders and Stroke-Alzheimer's disease and Related Disorders
Association criteria for probable AD.

- The progressive supranuclear palsy (PSP) patients will have met the NINDS-SPSP
criteria for probable PSP, which requires vertical supranuclear gaze palsy, prominent
postural instability, and falls in the first year of onset, as well as a number of
other clinical features.

- The DLBD patients will meet the Consensus Criteria for the clinical diagnosis of DLBD.

- The healthy controls will be matched to the PD patients on such variables as sex, age,
education level, and ethnicity.

- The essential tremor (ET), multiple system atrophy (MSA), myasthenia gravis (MG),
multiple system atrophy (MSA), Parkinson's disease dementia (D-PD), and Spinal Cord
Injury (SCI) patients will meet the generally-accepted diagnostic criteria for these
disorders.

Exclusion Criteria:

- Drug abuse.

- Any other known and potentially confounding condition that could reasonably be
expected to interfere with the study assessments.

- Under age 18.

- Over age 80.

- Smoker.

- Pregnant or nursing.

- Healthy control with a first degree relative who has a neurodegenerative disease.