Differences Between Alzheimer’s And Parkinson’s Disease
Do you know the differences between Alzheimer’s and Parkinson’s disease? These diseases are among the most common causes of dementia. Learn more about them in this post.
First, we must say that both of these diseases are two of the causes of dementia. However, it is important to keep in mind that these are two very different diseases. In addition, it should be made clear that having any of these conditions does not always lead to the development of dementia (although this occurs in most cases).
In this sense, we know that between 20 to 60% of people with Parkinson’s disease end up developing dementia.
In a study by Buter et al. (2008), published in the journal Neurology, in which 233 patients with Parkinson’s disease participated, it was observed that about 60% of them developed Parkinson’s dementia over a 12-year period.
But what is dementia? This concept refers to the set of symptoms that arise as a result of neurological damage or disease. These symptoms involve the loss or weakening of the mental faculties and mainly affect three different areas: the cognitive area (loss of memory or changes in reasoning), the behavioral area (changes in behavior), and the personality area (changes in personality, irritability, emotional lability, among other things).
“There is nothing that is a clearer sign of dementia than doing something repeatedly and hoping that the results will be different.”
-Albert Einstein-
Differences Between Alzheimer’s And Parkinson’s Disease
We will group the differences between both diseases into different blocks and explain what each one consists of. All of them were extracted from two reference manuals in psychopathology.
The first block of differences between Alzheimer’s and Parkinson’s refers to their types of symptoms, which are as follows:
Cognitive symptoms
One of the main differences between these two diseases is related to the way they affect the cognitive area. In the case of Parkinson’s, there are failures in data recovery (memory), while in Alzheimer’s, failures occur previously in the memory process (data coding). In addition, memory and attention are most affected in Alzheimer’s than in Parkinson’s.
Motor symptoms
In the case of Parkinson’s, there is the so-called parkinsonism, a clinical syndrome characterized by the following symptoms: stiffness, tremor, bradykinesia (slow movement), and postural instability. In contrast, in Alzheimer’s, parkinsonism is very rare.
On the other hand, stiffness and bradykinesia appear very often in Parkinson’s, while in Alzheimer’s these symptoms appear only occasionally. Finally, tremor is a typical symptom of Parkinson’s, but rare in Alzheimer’s.
Psychotic and other symptoms
In addition to the symptoms we have already mentioned, other symptoms can appear in both diseases. For example, in Alzheimer’s disease, delirium appears occasionally, while in Parkinson’s disease, it practically does not. It is important to remember that delirium is an organic disorder that mainly affects awareness and attention.
In relation to psychotic symptoms, visual hallucinations may appear in both diseases, more or less in the same proportion. There may also be delusions, frequent in Alzheimer’s and occasional in Parkinson’s.
Pathological symptoms
Another difference between both diseases is related to the brain (substances, neurotransmitters, and atypical structures). For example, while senile plaques typically appear in Alzheimer’s (extracellular deposits of molecules in the brain’s gray matter), in Parkinson’s they rarely appear.
The same occurs with other structures, such as neurofibrillary tangles, which appear a lot in Alzheimer’s, but very rarely in Parkinson’s.
On the other hand, Lewy bodies appear more often in Parkinson’s than in Alzheimer’s. When it comes to neurotransmitters, we know that acetylcholine deficiency often occurs in the brains of people with Alzheimer’s, but only occasionally in people with Parkinson’s.
Finally, in Parkinson’s, there is a dopamine deficit, something that does not occur in Alzheimer’s.
Age of onset
The age of onset is also different. Parkinson’s usually appears between 50 and 60 years, appearing before Alzheimer’s, which usually appears from the age of 65.
Prevalence
The prevalence of Alzheimer’s dementia is higher than that of Parkinson’s dementia. According to DSM-5 (2014), it is 6.4% in Europe.
Type of dementia
As for the type of dementia, in Alzheimer’s, it is cortical (it involves the involvement of the cerebral cortex), while in Parkinson’s it is subcortical (it involves the subcortical areas of the brain).
In this sense, it is noteworthy that cortical dementias usually carry cognitive symptoms, while subcortical dementias carry motor symptoms. However, both types of symptoms can be combined to a greater or lesser extent.
It is worth remembering that cortical dementias include Alzheimer’s, frontotemporal dementia, Creuzfeldt-Jacob dementia, and Lewy body dementia, while subcortical dementias include Parkinson’s, Huntington’s disease, and HIV dementia, mainly.
Read Also: What Is Leptomeningeal DIsease?
