What is Parkinson’s Disease?

Parkinson's Disease (PD) is a neurodegenerative disease where the connections between the brain and body progressively fail. The neural pathways between your brain and your foot muscles are no longer communicating effectively, causing problems such as freezing of gait, also known as 'Parkinson's disease walk' or 'Parkinsonian gait.'

According to the Parkinson’s Disease Foundation, more than 10 million people worldwide currently live with Parkinson’s Disease, and 70% of those individuals will fall, which further restricts activity due to fear of future falls. 1,2

Individuals with Parkinson’s have a 2-9 times increased risk of falls compared to healthy individuals of the same age.3

PD is a complex disease that primarily affects motor function, but can also cause depression and cognition changes. Every person with PD presents differently, both in their symptoms and the speed of their progression.

Parkinson's Disease affects the neural circuits that allow the brain to function and enable automatic, smooth movements. As a result, many people with PD will likely show signs of altered walking mechanics at the initial stages of diagnosis, and as the disease progresses, they may experience something called freezing of gait.4

Freezing of gait or Parkinson's disease walk is understood as the inability to take the next step while walking.

Although Parkinson’s Disease is a very involved neurologic disease, the latest research shows that physical therapy and external cues from technology such as NexStride can significantly improve quality of life and overall mobility.5

Motor Symptoms

Tremors are a very common symptom in PD, with 80% of individuals experiencing this symptom.9 Tremors are the uncontrollable slow, rhythmic shaking typically seen at rest in PD. The severity of PD is classified by if a person has tremors on one side or both sides.10 

Bradykinesia, or slow movement, is a very common symptom of Parkinson’s Disease. The reduction in speed of movement reduces the ability for muscles to produce force.6 Bradykinesia causes slower and smaller movements. For example, the average walking speed of someone with PD is 94 cm/s whereas a safe speed to cross a crosswalk is 120 cm/s.11-13 If someone is bumped or missteps, they may not be able to step fast enough to catch themselves.14 

Rigidity seen in Parkinson’s Disease is when there is a contraction of all the muscles in the trunk leading to overall stiffness and stooped posture.14 This increased stiffness in the trunk can significantly affect balance, and also cause increased muscle fatigue which can decrease the control of balance.15 Luckily, the medication used to treat Parkinson's, Levodopa, can significantly improve rigidity.14

Postural control is the ability to maintain balance. Overall postural control is decreased in individuals with Parkinson’s Disease due to extreme stiffness in the trunk muscles. 3 Postural instability has shown to begin within the first two years of diagnosis for about one third of patients.3 People with Parkinson's Disease are affected in multiple areas of postural control including their balance while standing and balance during dynamic activities like walking.3 When someone has an external perturbation, their reflexes aren’t effective to catch themselves like a healthy individual. This is due to the decreased ability for their muscles to create power as seen with bradykinesia. 

Gait (walking) changes are the primary motor symptom seen in Parkinson’s Disease. Bradykinesia, rigidity, and postural instability all contribute to the gait disturbances seen.16 Specific changes include reduced walking speed, increased time with two feet on the ground (shuffling), and decreased step length.11,17,18 These gait changes are increased during the “off” stage of medication or when the dose is wearing off.19

The motor symptoms seen in Parkinson’s Disease contribute to the increased risk of falls. Individuals are more susceptible to falls due to decreased postural control and bradykinesia.3 Not only are falls critical with potential consequences of injury, but they can lead to fear of falling which affects quality of life. 53% of individuals with Parkinson’s Disease report fall-related activity avoidance due to this fear.20 

Freezing of gait is defined as reduced ability to step forward despite the intention to walk.5

'Freezing of gait,' also known as 'Parkinson's Disease walk' or 'Parkinsonian gait,' is an advanced symptom of Parkinson's Disease and might need more than medication to be treated. The other forms of Freezing of Gait are shuffling and trembling in place.

Non-Motor Symptoms

Parkinson’s Disease (PD) affects a part of the brain called the prefrontal cortex that is responsible for thought processing. This is important because PD affects the ability of a person to plan a movement—specifically preparation, initiation and execution of a movement.21,22 Action such as changing direction, turning and performing tasks one after another are difficult for individuals with Parkinson’s Disease that have cognitive decline.17,22 It also affects the ability to have a goal and to make decisions. Individuals with cognitive deficits have an increased chance of experiencing Freezing of gait.23 

Dual tasking is when there is a motor task and cognitive task being performed at the same time such as walking while talking.11,17,18 Walking changes increase during a dual motor and cognitive task because they are distracted with their through processes and can’t think about walking.24

Individuals with Parkinson’s Disease have decreased frequency of saccades or fast eye movements between the areas of the room a person is looking at. Eye saccades help assess visual information in a room for someone to pay attention to while they walk.26 This plays a role in spatial awareness and overall attention to one’s surroundings during motor activities like walking. It plays a role in visual observation which could lead to trips and falls.26

Sleep disturbances are extremely common in individuals with Parkinson's Disease (PD). Individuals with PD sleep an average of 5 hours per night. This is due to a combination of factors including sleep apnea, insomnia, night time urinary frequency, and nighttime hallucinations.9 

50% of those withParkinson's Disease (PD) will experience depression during the course of their diagnosis. PD causes changes in the neurotransmitters dopamine, norepinephrine, and serotonin, which regulate mood and motivation, therefore depression is very common. It is very important to discuss these changes in mood with a doctor.2 

Hypophonia refers to the soft, hoarse, and monotone voice that many individuals with Parkinson’s Disease have. This is because there are changes in the vocal cord structure, not allowing for proper vibration of the vocal cords to produce sound.9

Fatigue is seen in earlyParkinson's Disease (PD) and can come before motor symptoms. Fatigue does not often improve with medication. It has been shown individuals with deficits in executive function or cognition may have increased fatigue.6 

What Causes Parkinson’s Disease?

The basal ganglia, situated in the middle of the brain, is in charge of regulation of movement specifically muscle contraction, force, and coordination of movements.6

The basal ganglia communicate with other structures in the brain to control eye movement, thought processing, regulation of emotion, sleep and wakefulness, and motivation.6 This structure is also in charge of automatic motor movements like walking, changing from one motor activity to another, and knowing where your body is in space.7

Within the basal ganglia is a structure called the substantia nigra. In Parkinsons' Disease (PD), the dopamine-producing neurons in the substantia nigra degenerate, causing the symptoms seen in PD.6

Dopamine is a chemical, also known as a neurotransmitter, that excites the pathways within the basal ganglia. The lack of dopamine seen in Parkinson’s Disease causes a decrease in the signals sent from the basal ganglia to other structures in the brain.6

The basal ganglia communicates with other areas of the brain, therefore there are more than just motor symptoms seen in PD. The basal ganglia works with the limbic system, which controls emotions, the oculomotor system that controls eye movements, and the prefrontal cortex associated with cognitive changes.6

Scientists still haven’t found exactly why people develop PD, though research shows there may be a correlation with genetics, environment (specifically herbicides and pesticides), age over 60, and the male sex.8

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Want to learn more about NexStride?

NexStride can give you back your mobility and help you to stay active. Staying as active as possible is crucial for managing Parkinson's Disease and its symptoms, such as freezing of gait or Parkinsonian gait.

How NexStride Works
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