Definition
What is Parkinson’s disease
Il Parkinson’s diseaseor Parkinson’s disease, is one neurodegenerative pathology which affects the central nervous system.
Parkinson’s disease is mainly related to degeneration of nerve cells located in a deep area of the brain (substantia nigra) that produce dopamine (neurotransmitter) responsible for activating circuits that control movement and balance.
Parkinson’s disease: a movement disorder
Parkinson’s disease falls into the category of movement disorderssince it is characterized by the appearance of motor symptomscome tremor at restslowness and decrease of movements (bradicinesia), rigidity and associated with instability of posture and/or gait.
Parkinson’s disease is one degenerative disease characterized by a slow and progressive evolution: the first symptoms are evident when 60-80% of the cells that produce dopamine are damaged.
Characteristics of the disease
Why and how does Parkinson’s disease develop?
An important feature of Parkinson’s disease is progressive and chronic degeneration of neurons from the black substance (a small area of the central nervous system), whose axons connect to the striated nucleus. Per degeneration it means the loss of some groups of nerve cells or structures connected to each other.
Black substance
The black substance – also known as black substance of Sommering – belongs to those anatomical structures which, taken together, constitute the basal ganglia. The term substantia nigra derives from the fact that this area is darker than the surrounding cerebral area; this coloring, in particular, is linked to the presence in the cells of a pigment, called neuromelanina. Due to the slow but considerable loss of cells that characterizes Parkinson’s disease, less brownish discoloration has been observed in these areas of the patients’ brains.
I neurons of the subtantia nigra produce the dopaminewhich acts on the striatum acting as a chemical messenger for the control of:
- Posture;
- Movement;
- Marcia.
This is the so-called nigro-striatal route forming part of extrapyramidal system.
In Parkinson’s disease, failure of dopamine release in the striatum leads to a series of severe dysfunctions of the basal ganglia, thalamus, and cerebral cortex. These alterations depend on motor and non-motor disturbances, including tremor, rigidity, bradykinesia and loss of balance.
Lewy bodies
A hallmark of Parkinson’s disease, from an anatomical-pathological point of view, is represented by the presence of Lewy bodies (named after the neurologist FH Lewy who identified them in 1912), which accumulate particularly in the subtantia nigra. Lewy bodies are spherical inclusions, found on histological examination, mainly formed by aggregates of alpha-synuclein, a protein in an insoluble form.
dopamine
Another important feature of the cells of the subtantia nigra is the production of dopamine. Due to the degeneration of Parkinson’s, a serious deficiency of the neurotransmitter occurs in the projection area of the nigral dopaminergic neurons, i.e. in the neostriatum.
Briefly, dopamine is an essential neurotransmitter for motor activity. In fact, it allows movements to be carried out quickly and harmoniously, regulating the activity of the basal ganglia which, as described initially, are the regulatory center of the brain as regards all motor activity.
Epidemiology
Parkinson’s disease: how common is it?
Parkinson’s disease is the second most common neurodegenerative disease, after Alzheimer’s disease.
The prevalence of Parkinson’s varies widely throughout the world, with estimates ranging from 15/100,000 inhabitants in China to 150-200/100,000 inhabitants in Europe and North America.
In Italy, according to the latest data from the Ministry of Health, people affected by Parkinson’s disease are about 230,000, of whom about 5% are under the age of 50, while 70% are over the age of 65 years. Due to the growing aging of the general population, the number of cases is expected to double by 2030, according to estimates.
The average age of onset of Parkinson’s disease is about 60 years; this means that the majority of people at risk are between the ages of 50 and 70.
Who is most affected by Parkinson’s?
70% of people with Parkinson’s disease are over 65 years of age. The disease rarely occurs, however, before the age of 50 (5%).
Parkinson’s disease is slightly more common in men, with an incidence 1.5-2 times higher than in women.