Definition and Overview

Parkinson’s disease is a degenerative condition that affects the nervous system. It is considered a movement disorder since it mainly targets the motor system. However, it can also present with other symptoms that are not related to movements, such as autonomic dysfunction, sleep disturbances, and psychiatric symptoms.

Approximately seven million individuals all over the world have Parkinson’s disease with incidence peaking during the early 60s. The majority of the patients are diagnosed after they reached 50 years old. Parkinson’s disease is progressive, and patients tend to have a shorter life expectancy.

Cause of Condition

Studies on Parkinson’s disease reveal that the condition is caused by the death of cells in a specific area of the brain known as the substantia nigra. These cells secrete dopamine, and thus, cell death results in decreased levels of dopamine in the body. This leads to hypokinesia or decreased motor activity in the body, requiring an individual to exert greater effort to perform a specific movement. On examination, patients with Parkinson’s disease are noted to have atrophy of the frontal cortex, with decreased melanin pigmentation in the midbrain.

Cell death in Parkinson’s disease has been attributed to the accumulation of a specific insoluble protein, known as alpha-synuclein, in the brain cells. Aside from this, several other factors, namely genetics, oxidative stress, and environmental conditions, are also believed to play a role in the development of Parkinson’s disease.

Studies in young individuals with Parkinson’s disease have revealed that genetics may contribute to the occurrence of this condition. Mutations in the PARK genes are responsible for the hereditary forms of Parkinson’s disease, which usually has an earlier onset. Meanwhile, oxidative stress, which is due to the production of free radical, has been associated with the non-hereditary form of Parkinson’s disease. Several risk factors for the development of Parkinson’s disease include family history, head injury, and pesticide exposure, to name a few. On the other hand, drinking coffee and use of estrogen replacement have been associated with a reduced incidence of this condition.

Key Symptoms

The majority of the symptoms of Parkinson’s disease are related to movement. These motor symptoms have been termed as “parkinsonism” with rest tremor being the most prominent. The tremor is most apparent when the extremity is at rest, and disappears during sleep and voluntary activity. It typically begins unilaterally, but may become bilateral in the long run. It is the most frequently encountered symptom, occurring in 85% of patients, although it may not be present at the onset of the disease in as much as 30% of the cases.

Bradykinesia, or slowness of movement, is another motor symptom. With bradykinesia, there is sluggishness in the entire process of moving, from initiation up to execution. Fine motor activity is likewise affected, resulting in decreased dexterity and problems with writing. Increased muscle tone in these patients results in rigidity, which is another motor symptom. With rigidity, there is resistance to movements because of the persistent contraction of the muscles. Disturbances in posture and gait also occur. The typical gait of a person with Parkinson’s disease is described as festinating or taking small shuffling steps. The patient’s posture eventually becomes stooped and unstable as the condition progresses, resulting in falls and injuries. Patients can also present with swallowing and speech difficulties, and mask-like faces.

Although motor symptoms are the most commonly noted symptoms, patients with Parkinson’s disease also experience a number of non-motor symptoms. Autonomic dysfunction may result in orthostatic hypotension (sudden decrease in blood pressure upon sitting or standing up), urinary urgency and incontinence, and constipation, among others. Sleep may be disrupted, with insomnia and drowsiness during the day. Sensory changes, such as a sense of numbness or pain, can also be present.

Patients with Parkinson’s disease can also experience neuropsychiatric symptoms. Cognitive disorders may occur, with patients experiencing difficulties in planning and executing complex tasks. Attention and memory may also be impaired. The risk for dementia also increases as the disease progresses. Alterations in the person’s mood are also common. Depression and anxiety are fairly common, occurring in about half of patients. Psychotic symptoms, specifically delusions and hallucinations, may likewise be experienced.

Who to See and Types of Treatments Available

Parkinson’s disease is best managed primarily by a neurologist, along with a multidisciplinary team of therapists and physicians. The ultimate goals of treatment are to maintain the patient’s functionality and improve the quality of life.

At present, there is still no absolute cure for this condition. Symptoms, however, can be significantly controlled with medications. These drugs are dopaminomimetic, which fall into one of several classes: a dopamine agonist, a MAO inhibitor, or a levodopa medication (dopamine precursor). The symptoms typically improved following the initiation of medical treatment using one drug. In time, however, these medications tend to lose their efficacy. Thus, within the first 5 years, other medications may have to be added to the treatment program in order to effectively manage the symptoms. Medications for Parkinson’s disease tend to have serious side effects. Dyskinesias, which are involuntary movements, are common in the long term. Thus, in the medical management of Parkinson’s disease, it is important to control the symptoms while minimizing the occurrence of drug-induced complications.

Other forms of treatment for patients with Parkinson’s disease include:

  • Rehabilitation
  • Occupational and speech therapy
  • Psychiatric evaluation may also help deal with the neuropsychiatric symptoms of the condition.
  • Palliative care, or specialized care for patients with chronic conditions, should also be offered to patients and their families. A combination of rehabilitation and palliative care treatments can significantly improve the quality of life of the patient.
  • Surgery, specifically deep brain stimulation, is usually the last resort and is offered when medications are no longer effective.

References:

  • National Institute of Neurological Disorders and Stroke -- www.ninds.nih.gov/disorders/parkinsons_disease
  • National Parkinson Foundation -- www.parkinson.org
  • Parkinson's Disease Foundation -- www.pdf.org
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