Neurological disorders often exhibit symptoms that overlap with several known conditions. A clear example of such an overlap is signs of Parkinson’s and tardive dyskinesia. This can make it easy to misdiagnose the issue. Further, certain early symptoms of these conditions can be subtle enough to go unnoticed, delaying diagnosis. While there are some differences in terms of severity, location, and progression of these conditions, here are 5 overlapping early symptoms of Parkinson’s and TD:

Tremors of the limbs
Tremors are one of the shared symptoms of Parkinson’s and tardive dyskinesia (TD). However, with Parkinson’s, one may primarily experience resting tremors that develop in the limbs when they are in a relaxed position. The tremors stop when there is any movement or slight increase in activity, which is why Parkinson’s tremors are referred to as resting tremors. This is a silent symptom that often gets overlooked till the condition progresses. It begins with a slight shaking of the hand but becomes more pronounced over time. With TD, these tremors are more prolonged, visible, irregular, and jerkier, indicating rapid dysfunction of the neural activity that controls these movements. Here, only a thorough clinical diagnosis can help confirm whether the underlying condition is Parkinson’s or TD.

Involuntary movements
While a shared symptom, the difference between involuntary movements observed with Parkinson’s and TD is the severity with which they develop. With Parkinson’s, one mainly experiences bradykinesia or slow movements of the hands and limbs. Although slow, these movements are characterized by the sudden writhing and twisting of the hands, legs, and even the face. However, with TD, the involuntary movements are often limited to the facial region affecting the mouth, ranging from excessive blinking of the eyelids in an uncontrolled repetitive pattern to even puckering and smacking of the lips. As the condition progresses, these reflexes get further out of control. Some may even experience facial grimaces, contortion in the form of pulling of facial muscles, tongue rolling, protrusion, and other involuntary movements that lead to lip biting.

Facial movements
Facial expressions are less of a visible symptom when it comes to diagnosing Parkinson’s. However, one does experience difficulties in swallowing and speaking due to the muscle stiffness that develops with the progression of Parkinson’s. However, with TD, the facial and oral movements, including lip smacking, puckering, and grimacing, worsen with disease progression. Note that these symptoms may be overlapping, but the distinction here is that with TD, the tongue will dart in and out of the mouth involuntarily, along with jaw movement issues like clenching, grinding, or lateral shifting. These symptoms can vary in terms of severity and progression of either disease.

Muscle rigidity
One of the most glaring overlapping signs of Parkinson’s and tardive dyskinesia is muscle rigidity. The severity of this symptom can vary from person to person. With Parkinson’s, bradykinesia causes slow movement of muscle groups, making it difficult to carry out daily tasks. So, one may have trouble tying shoelaces, buttoning up a shirt, and picking or gripping objects. Muscle rigidity also affects the face, making it difficult to maintain facial expression. However, this may not be as pronounced as the facial movements associated with TD. Further, with TD, the muscle rigidity is not as prominent as with Parkinson’s. However, the condition still triggers localized stiffness of the muscles, affecting movements in the facial and oral muscles. It can also affect the movement of limbs, making it difficult for one to carry out tasks that require fine motor skills.

Balance and gait issues
Posture and balance issues are overlapping symptoms of Parkinson’s and tardive dyskinesia. Parkinson’s mainly triggers postural instability that makes it difficult to stand up straight and maintain balance. Here, one develops a stooped posture, which increases the risk of falls. On the other hand, TD leads to postural changes extending to the trunk and hips, causing twisting or writhing movements in the affected areas. These uncontrolled movements can interfere with simple tasks that require standing, walking, or sitting. Although with TD, these symptoms are not as prominent, they can become a hindrance over time.

It is important to get examined upon noticing any of these early symptoms. A thorough clinical evaluation and comprehensive review of health history can help in identifying the cause of these movement-related issues. The diagnosis may involve physical examination and imaging or other tests to determine the exact cause.