Abstract
Parkinson's disease is a neurodegenerative disorder characterized by severe cognitive impairments. This is a condition of degeneration of substantia nigra of basal ganglia. Parkinsonism adversely influences the mental health of the person too. Parkinson's disease was first described in 1817 by James Parkinson. Parkinsonism patients may get severe complications like cognitive deficiency, which include loss of memory, attention difficulties, visual abnormalities, slow thinking, problems with word finding, and motor symptoms. Symptoms of this disease range from Parkinson's disease mild cognitive impairment (PD-MCI) to Parkinson's disease dementia (PDD). The primary motor symptoms are trembling in hands, arms, legs, jaw, and face; rigidity or stiffness of the limbs and trunk; slowness of movement; postural instability; and impaired balance and coordination. Studies on treatments of Parkinson's disease are progressing to prevent complications and sustain the normal functions of patients.
TopBackground
General Review on Parkinson’s Disease
Parkinson’s disease is a chronic, slow, progressive disorder characterized by degeneration of neurons that produce Dopamine in the Substantia Nigra near to the Basal Ganglia. It is also found that the presence of Lewy bodies and Lewy neuritis can also be the reason for Parkinsonism (Berg et al, 2014). The disease is characterized by a group of symptoms: tremors, bradykinesia or slowness of movement and postural instability or impaired balance and coordination (Armstrong & Okun, 2020). It is an unfortunate thing that PD can worsen as year goes on and reach to a stage of severe cognitive deficits and even psychosis. This leads to morbidity of patients, increased care giver burden and decreased prognosis. When patients develop cognitive impairment they may feel worthless and develop signs of depression. Later patients develop some signs of psychosis especially hallucinations and delusions. Finally there is a stage of disease where the patient will lose his or her insight completely. This is the most complex scenario of a patient with Parkinson’s disease (Zahodne& Fernandez, 2010).
In order to study Parkinson’s disease we need to have a brief look on anatomy and physiology of Basal Ganglia. Deep within the each cerebral hemisphere there are three nuclei collectively called Basal ganglia, which is inter-connected with the Cerebral cortex, Thalamus and Brainstem. Basal ganglia have variety of functions like motor control, cognition, emotions and learning. The nearby structures functionally connected to the Basal ganglia are the Substantia Nigra of the mid brain and sub-thalamic nuclei of the Diencephalon. Substantia Nigra is a core structure of the Basal ganglia which has cells responsible for producing Dopamine (Kordower et al, 2013). In addition to this the dopaminergic cells inside the Substantia Nigra may possess some aggregation of protein called Lewy bodies which may pre dispose Parkinsonism (Goedert et al, 2012). De-pigmentation or degeneration of Substantia Nigra can obviously result in drop in Dopamine and motor and non-motor symptoms responsible for Parkinson’s disease.
Epidemiology
Parkinsonism is the second commonest neurological disorder after Alzheimer’s disease that affects almost 1% of individuals older than 60 years with the prevalence of 0.5 -1% and rising to 1-3% among people older than 80 years (Kalia & Lang, 2015). Among elderly population, both the prevalence and incidence of Parkinson’s disease are expected to increase by more than 30% by 2030. Prevalence of this disease is more in Europe, North America and South America compared with African, Asian and Arabic countries (Kouli et al, 2018).
Key Terms in this Chapter
Atrophy: A medical condition of wasting away or shrinking of the cells or muscles often occurs due to prolonged immobility or disuse.
Degeneration: A process of deterioration of tissues and loss of function.
Idiopathic: Unknown cause.
Necrosis: Death of the cells.
Dyskinesia: Involuntary movements that is difficult to control or cannot control.
Tremor: An involuntary, rhythmic muscle contraction leading to shaking movements in one or more parts of the body.
Dystonia: A neurological state characterized by muscle contractions responsible for slow repetitive movements or abnormal postures.
Morbidity: A condition of prolonged suffering with a disease that disrupts the quality of life of a person.
Bradykinesia: A physical state of impairment of voluntary motor control characterized by slow movement.
Rigidity: A condition of increased muscle tone with stiffness or inflexibility of the muscles.
Autosomal: A specific gene located in the non sex chromosome.
Dementia: Impaired ability to recall, think or make decisions which influence the activities of daily living.