The Differences Between Parkinson’s Disease And Alzheimer’s
Parkinson’s and Alzheimer’s diseases, respectively, are the causes of two common types of neurological disorders related to dementia.
However, there are many aspects that allow us to distinguish between one disease and another; In this article we will know The most important differences between Parkinson’s disease and Alzheimer’s
We must be aware of the differences between illness and dementia, since illness does not always lead to dementia (cognitive alterations), although it generally does.
Thus, the term dementia refers to a set of symptoms that appear as a consequence of neurological damage or disease.
Parkinson’s disease, for its part, does not always lead to dementia (yes it does in 20-60% of cases); On the other hand, Alzheimer’s disease does usually always lead to dementia (and early on).
Differences between Parkinson’s disease and Alzheimer’s
Regarding the differential diagnosis between Parkinson’s and Alzheimer’s diseases, we find several differences in terms of their presentation. We will see them in different blocks:
1. Dementia
In Alzheimer’s, dementia appears early, and attention and memory are especially affected. Instead, In Parkinson’s, if dementia appears, it does so later
On the other hand, Alzheimer’s dementia is cortical (involvement of the cerebral cortex), and Parkinson’s dementia is subcortical (involvement of subcortical areas).
Broadly speaking, cortical dementias involve cognitive alterations, and subcortical dementias involve motor alterations.
Delirium appears occasionally in Alzheimer’s disease, and in Parkinson’s this occurs less often.
In both Alzheimer’s and Parkinson’s, visual hallucinations may appear occasionally. On the other hand, Delusions typically appear in Alzheimer’s and in Parkinson’s they appear only occasionally.
3. Motor symptoms
parkinsonism (clinical syndrome characterized by tremor, bradykinesia, rigidity, and postural instability) is the first manifestation of Parkinson’s; However, this symptom is rare to appear in Alzheimer’s.
The same way, Rigidity and bradykinesia typically appear in Parkinson’s and occasionally in Alzheimer’s.
Tremor is typical in Parkinson’s and rare in Alzheimer’s.
4. Cognitive symptoms
Failures in retrieval appear in Parkinson’s, and failures in encoding (memory) in Alzheimer’s.
5. Pathological signs
Senile plaques in the brain They typically appear in Alzheimer’s, although rarely in Parkinson’s. Similarly, neurofibrillary tangles also typically appear in Alzheimer’s, but rarely in Parkinson’s.
Cortical Lewy bodies appear rarely in Alzheimer’s and more often in Parkinson’s (occasionally). Subcortical ones, on the other hand, are typical in Parkinson’s and rare in Alzheimer’s.
On the other hand, acetylcholine deficiency It is typical in Alzheimer’s and occasionally in Parkinson’s. Finally, dopamine reduction appears only in Parkinson’s.
6. Age of onset and prevalence
Finally, continuing with the differences between Parkinson’s disease and Alzheimer’s, we know that Parkinson’s appears earlier than Alzheimer’s (at 50-60 years of age), while Alzheimer’s usually appears a little later, after 65 years of age. .
On the other hand, regarding dementia, the prevalence of Alzheimer’s dementia is higher (it is the first cause of dementia), and this is 5.5% in Spain and 6.4% in Europe.
Now that we have seen the differences between Parkinson’s disease and Alzheimer’s, let’s learn in more detail what the symptoms of each of these diseases are:
1. Alzheimer’s
Alzheimer’s disease is a neurodegenerative disease that manifests as cognitive impairment (dementia), behavioral disorders and emotional disorders. When it leads to dementia and according to the DSM-5, it is called Major or Mild Neurocognitive Disorder due to Alzheimer’s disease.
The symptoms of Alzheimer’s change as the disease progresses. We can differentiate three types of symptoms according to the three phases of Alzheimer’s:
1.1. First phase
The first deterioration appears and lasts between 2 and 4 years. Anterograde amnesia occurs (inability to create new memories), changes in mood and personality, as well as impoverished language (anomias, circumlocutions and paraphasias).
1.2. Second stage
In this phase the deterioration continues (lasts between 3 and 5 years). Aphaso-apraxo-agnosic syndrome appears, retrograde amnesia and a deterioration in judgment, as well as alterations in abstract thinking. Instrumental activities of daily living (IADL), such as going shopping or calling the plumber, are already affected.
The patient is no longer able to live without supervision, and presents a space-time disorientation
1.3. Third phase
In this last phase the deterioration is already very intense, and the duration is variable. It is the advanced phase of the disease. Here, self-psychic disorientation and that of other people appear, as well as mutism and the inability to carry out basic activities of daily living (BADL) such as eating or washing.
Gait alterations also appear (there is “walking in small steps”). On the other hand, Kluver Bucy Syndrome can manifest ; It is a syndrome in which there is a lack of fear in the face of stimuli that should generate it, absence of risk assessment, meekness and obedience along with indiscriminate hypersexuality and hyperphagia, among others.
Finally, in this phase the patient ends up bedridden, characteristically adopting a fetal position.
2. Parkinson’s
Parkinson’s is a chronic neurodegenerative disease, characterized by different motor disorders such as bradykinesia, rigidity, tremor, and loss of postural control
Between 20 and 60% of patients with Parkinson’s disease develop Parkinson’s dementia (cognitive impairments). The DSM-5 calls this dementia Major or mild neurocognitive disorder due to Parkinson’s disease.
Once dementia appears, the symptoms consist of: failures in memory recovery processes, decreased motivation (apathy, asthenia and abulia), bradypsychia (slowing of the thinking process) and impoverishment of language. Bradykinesia (slowness of movement) also appears, although the aphaso-apraxo-agnosic syndrome does not appear as in Alzheimer’s dementia.
Visuospatial and visuoconstructive alterations also appear and finally, Parkinson’s is strongly related to depression.
On the other hand, it is common in Parkinson’s dementia. the presence of dysexecutive syndrome (alteration of the prefrontal lobe).
Conclusion
As we have seen, the differences between Parkinson’s disease and Alzheimer’s are notable, although they share many other characteristics. That’s why It is important to make a good differential diagnosis in order to be able to carry out an appropriate treatment for each case and patient.
