Can Parkinson’s Disease Turn into Alzheimer’s?

Parkinson’s disease (PD) and Alzheimer’s disease (AD) are two of the most common neurodegenerative disorders, often mistakenly believed to be sequential stages of the same illness.

However, it’s crucial to understand that Parkinson’s disease does not transform into Alzheimer’s disease.

They are separate and distinct conditions, each with its unique biological hallmarks, primary symptoms, and disease progression.

Different Pathologies: The Origins of the Difference

The basic disparity between PD and AD is the irrespective brain areas involved and the kind of protein alterations that congregate.

Parkinson’s Disease: Mainly the degeneration of the dopamine-producing cells of the substantia nigra, which is an area of the brain critical to motor control. The accumulation of pathologically altered proteins, the so-called abnormal alpha-synuclein, is the likely hallmark pathological feature of PD, as these form clumps, named as such as Lewy bodies in neurons. These Lewy bodies are responsible for the motor symptoms (tremor, rigidity, bradykinesia) and many non-motor symptoms of PD.

Alzheimer’s Disease: Primarily characterized by the accumulation of two abnormal proteins: beta-amyloid plaques (deposits between brain cells) and tau tangles (twisted fibers within brain cells). The most significant abnormalities of the brain lie in regions that deal with memory, language, and executive functions, and result in the typical cognitive impairment in AD.

Overlapping Symptoms and Co-occurrence

Though different, PD and AD are capable of showing some common symptoms, especially upon advancement of either of the diseases. Cognitive impairment, including memory issues and executive dysfunction, can occur in later stages of Parkinson’s disease, a condition often referred to as Parkinson’s Disease Dementia (PDD).

Similarly, individuals with Alzheimer’s may experience some motor symptoms, though typically less pronounced than in PD. It’s also important to note that co-occurrence is possible. An individual can be diagnosed with both Parkinson’s disease and Alzheimer’s disease independently.

As such, they have both conditions at the same time in their brain, which have very unique pathological alterations. Nonetheless, it is not the conversion of one disease into another but two diagnoses that exist in the same individual.

 Conclusion

The misconception that Parkinson’s can “turn into” Alzheimer’s can lead to confusion and anxiety. It is important to realize that there are distinct conditions that have different underlying mechanisms of action because this knowledge is important to accurate diagnosis, proper treatment, and realistic views of how the disease will progress.

Although both diseases are extremely troublesome, research is still underway, and lately it yields in outlining these diseases and sets the path to more precise treatment and a better life for ill individuals.

Dr. Navin Tiwari
Consulting Neurologist