Parkinson's Disease: Tracking The Signs

During the development of neurodegenerative disease, several years may pass before overt clinical symptoms occur, the prodromal period.  Consider the fact that patients with neurodegenerative disease often present when family members have noticed cognitive changes (e.g., memory impairment, difficulty with routine activities, withdrawal) or motor symptoms (tremor, shuffling, freezing gait, falls) that bring them into the clinic.  For a system as robust as the human brain, with many layers of redundant connections, how much degradation must have already occurred to become noticeable at a gross behavioral level?  Can changes in motor systems give us clues before cognitive deficits develop?    

For Parkinson's Disease, several oculomotor signs are well-known.  First, squarewave jerk describes small horizontal flicks of the eye that occur in rapid succession, which occur more frequently in PD patients than normal controls.  Second, targeting eye movements are smaller than in normal controls.  Third, the timing of targeting eye movements are prolonged as compared to normal controls.         

In collaboration with NYU Shanghai, a Parkinson's clinic screened their patient population with the COBRA task.  Patients were categorically assigned to disease groups (left-hemisphere or right-hemisphere Parkinson's Disease, Multiple System Atrophy, Progressive Supranuclear Palsy, Rapid Eye Movement Behavior Disorder) based upon their diagnosis.    

Parkinson's Disease commonly affects one hemisphere of the brain more severely than the other, amplifying motor symptoms on the opposite side of the body.     

Many research studies have shown that oculometrics can:

  • quantify disease severity, progression, or regression.

  • evaluate the effectiveness of protective or restorative drugs

  • characterize the deficits associated with

  • detect health and performance impairments related to

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