Parkinson’s disease (PD) is a progressive neurological disorder characterized by the loss of dopamine-producing neurons in the brain, leading to movement problems. While the public is familiar with classic symptoms like resting tremor and slowness of movement, PD also involves a wide range of non-motor and unusual motor manifestations that can appear strange to an outside observer. These lesser-known behaviors often stem from the complex interplay between the disease’s progression, changes in brain chemistry, and the side effects of necessary medications. Understanding these peculiar symptoms provides a more complete picture of life with Parkinson’s.
Involuntary Movements Induced by Treatment
One of the most noticeable “strange behaviors” is dyskinesia, which refers to abnormal, uncontrolled, and involuntary movements. Dyskinesia is paradoxical because it is not a symptom of the disease itself but a side effect of the long-term use of levodopa, the most effective medication for treating Parkinson’s motor symptoms. Levodopa converts into dopamine in the brain, but after years of use, remaining neurons lose their ability to release dopamine steadily. This irregular stimulation of the brain’s motor circuits results in an excess of movement, contrasting sharply with the stiffness the drug is meant to treat.
These movements can manifest in various ways, often described as fidgeting, writhing, swaying, or head bobbing. They are often fluid and dance-like, which is why observers may mistake them for voluntary restlessness. The most common type is peak-dose dyskinesia, which occurs when the medication is at its highest concentration in the blood.
Nearly 80% of patients develop some degree of levodopa-induced dyskinesia. While some patients prefer dyskinesia over the stiffness of being “off” medication, the movements can become severe enough to interfere with daily activities and reduce the quality of life.
Compulsive Behaviors and Impulse Control Disorders
Another set of peculiar behaviors involves a loss of inhibition and the development of compulsive tendencies, grouped as Impulse Control Disorders (ICDs). These are typically linked to medications called dopamine agonists, which directly stimulate dopamine receptors in the brain. The behaviors are thought to arise from an overstimulation of the brain’s reward pathways, leading to a focus on immediate gratification.
Common ICDs include pathological gambling, compulsive shopping, hypersexuality, and binge eating. These goal-directed behaviors can severely strain finances, personal relationships, and a patient’s health. In some cases, patients may develop Dopamine Dysregulation Syndrome (DDS), where they compulsively take more drug than prescribed, which leads to complications like severe dyskinesia or mania.
The most unique compulsion is Punding, which involves engaging in complex, non-meaningful, and repetitive tasks. Punding behaviors can include endlessly sorting objects, disassembling electronics, or meticulously organizing insignificant items. Unlike ICDs driven by pleasure, punding lacks discernible purpose and can be highly time-consuming, causing the patient to neglect other important aspects of their life. These behaviors affect a minority of treated patients, especially those on dopamine agonists, and require careful medication management.
Acting Out Dreams and Altered Reality Perception
The disease can dramatically affect consciousness and perception, blurring the line between sleep and wakefulness. One such condition is REM Sleep Behavior Disorder (RBD), where the normal paralysis that occurs during REM sleep is absent. During this phase, people physically act out vivid and intense dreams, often involving fighting, running, or falling.
These actions can result in injury to the patient or their bed partner, as they punch, kick, or jump out of bed while asleep. RBD frequently predates the motor symptoms of Parkinson’s by many years, and its presence is associated with an increased risk of developing visual hallucinations later on.
Visual hallucinations, which are perceptions without an external stimulus, are another common feature, especially in advanced disease or as a side effect of dopaminergic medications. These hallucinations are typically complex, well-formed images, often involving people, children, or animals. Patients may also experience minor hallucinations, such as “presence hallucinations,” where they feel someone is standing right behind them, or “passage hallucinations,” where they see fleeting shadows. These perceptual disturbances involve the intrusion of dream-like visual imagery into the patient’s waking state.
Peculiarities of Movement and Communication
The underlying motor dysfunction of Parkinson’s disease presents its own set of confusing physical manifestations. Freezing of Gait (FOG) is a common episodic symptom where the patient suddenly experiences the brief, involuntary sensation of their feet being stuck to the floor. This sudden inability to move often occurs when initiating a step, turning, or passing through narrow spaces.
Another unusual gait pattern is festination, defined as a progressively shortened stride length accompanied by an increase in step frequency. This makes the person appear to be hurrying forward to catch up with their center of gravity. Festination is linked to the patient’s stooped posture and a loss of postural reflexes, creating a forward lean that propels them faster until they risk a fall. Both FOG and festination are highly disabling and often associated with longer disease duration.
Communication is also affected, most notably with a “masked face” (hypomimia) and soft speech (dysarthria). The masked face is a lack of spontaneous facial expression and blinking, which can make the patient appear emotionless or detached. The voice often becomes soft, monotone, and sometimes rapid, making it difficult for others to understand the person. These peculiarities are a direct result of the reduced motor control characteristic of the disease.