The Differences Between Alzheimer’s And Parkinson’s
Do you know the differences between Alzheimer’s and Parkinson’s? First of all, we must say that both diseases are two of the causes of dementia. Let’s be a little more specific. According to data from the WHO (World Health Organization), dementia due to Alzheimer’s disease represents 60-70% of all cases of dementia in the world.
However, it is important to remember that they are two very different diseases. In addition, we must make it clear that having one of the conditions does not always lead to the development of dementia (although it does occur in most cases). In this sense, we know that between 20-60% of people with Parkinson’s disease end up developing dementia.
Buter et al. (2008) conducted a study that was published in the journal Neurology . It was performed in 233 patients with Parkinson’s disease. The researchers were able to observe that about 60% of them developed Parkinson’s dementia over a period of 12 years.
So what is dementia? It refers to the set of symptoms that occur as a consequence of neurological damage or disease. These symptoms involve loss or impairment of mental abilities and mainly affect three different areas: cognitive (such as memory loss or changes in reasoning), behavioral (changes in behavior) and personality (changes in character, irritability and emotional lability, among others).
The differences between Alzheimer’s and Parkinson’s
We will group the differences between the two diseases in different blocks and explain what each of them consists of. All are taken from two reference psychopathological handbooks: Belloch, SandÃn and Ramos (2010) and DSM-5 (APA, 2014).
The first group of differences between Alzheimer’s and Parkinson’s refers to their type of symptoms. Let’s see what they are.
Cognitive symptoms
One of the biggest differences between these two diseases is related to the way they affect the cognitive area. In the case of Parkinson’s, there is an error in retrieving data (memory), while in Alzheimer’s there are errors earlier in the memory process (data coding). Furthermore, memory and attention are more affected by Alzheimer’s than in Parkinson’s.
The differences between Alzheimer’s and Parkinson’s: Motor symptoms
In the case of Parkinson’s, the so-called parkinsonism appears, a clinical syndrome characterized by the following symptoms: stiffness, tremor, bradykinesia (slowness of movement) and postural instability. In contrast, parkinsonism is very rare in Alzheimer’s disease.
On the other hand, stiffness and bradykinesia occur very often in Parkinson’s disease, while these symptoms only occur occasionally in Alzheimer’s disease. Finally, tremor is a typical symptom of Parkinson’s disease, but quite rare in Alzheimer’s.
Psychotic and other symptoms
In addition to the symptoms we have already mentioned, other symptoms can occur in both diseases. For example, in Alzheimer’s disease, delirium occurs occasionally, while it rarely does in Parkinson’s. It is important to remember that delirium is an organic disorder that mainly affects consciousness and attention.
In the case of psychotic symptoms, visual hallucinations can occur in both diseases, more or less in the same proportion. Delusions can also occur. They often occur in Alzheimer’s and sometimes in Parkinson’s.
The differences between Alzheimer’s and Parkinson’s: Pathological symptoms
Another difference between these two diseases is related to the brain (neurotransmitters and atypical structures). For example, while senile plaques usually appear in Alzheimer’s (extracellular deposits of molecules in the gray matter of the brain), it rarely ever occurs in Parkinson’s.
The same thing happens with other structures. For example, neurofibrillary tangles, which are common in Alzheimer’s but very rare in Parkinson’s.
On the other hand, Lewy bodies occur more often in Parkinson’s than in Alzheimer’s. Regarding neurotransmitters, we know that acetylcholine deficiency often occurs in the brains of people with Alzheimer’s, but this only occurs occasionally in people with Parkinson’s.
Also remember that there is a dopamine deficiency in Parkinson’s disease, which does not occur in Alzheimer’s disease.
Age before the onset of the disease
The age at which the disease starts is also different. First, Parkinson’s usually appears before Alzheimer’s (between 50 and 60 years of age), while Alzheimer’s usually occurs in patients older than 65 years.
The differences between Alzheimer’s and Parkinson’s: Prevalence
The incidence of Alzheimer’s dementia is higher than for Parkinson’s dementia. According to DSM-5 (2014), it is 6.4% in Europe.
Type of dementia
Finally, in the case of Alzheimer’s, dementia occurs earlier than in the case of Parkinson’s.
When it comes to the type of dementia, it is in Alzheimer’s disease cortical (it involves the involvement of the cerebral cortex). In contrast, Parkinson’s dementia is subcortical (it involves the subcortical areas of the brain).
In this sense, it is important to note that cortical dementia generally carries cognitive symptoms, while in subcortical, both types of symptoms can be combined to a greater or lesser degree.
Let’s remember something. On the one hand, cortical dementia includes Alzheimer’s, frontotemporal dementia, Creutzfeldt-Jakob disease and Lewy body dementia. Subcortical dementia , on the other hand, mostly includes Parkinson’s disease, Huntington’s disease, and HIV-related dementia.
