Parkinson’s disease is a progressive neurodegenerative disorder characterized by motor symptoms such as tremors, rigidity, bradykinesia, and postural instability. However, Parkinson’s disease is associated with many non-motor symptoms as well that significantly impact quality of life. Parkinson’s disease patients frequently have comorbid conditions, which are other chronic medical conditions that co-occur with Parkinson’s disease. Understanding the common comorbidities of Parkinson’s disease is important for comprehensive patient care.
Psychiatric Disorders
Psychiatric disorders are very common in Parkinson’s disease patients. It is estimated that over 50% of Parkinson’s disease patients experience anxiety and depression at some point during the course of their illness. Anxiety symptoms can precede the onset of motor symptoms in some cases. Depression is considered one of the most important determinants of quality of life in Parkinson’s disease. The biological mechanisms linking Parkinson’s disease and depression are not fully understood but likely involve dopaminergic dysfunction and neuroinflammation. Treatment of depression and anxiety in Parkinson’s disease patients improves overall wellbeing.
Dementia
Dementia affects approximately 40% of Parkinson’s disease patients, with the risk increasing as the disease progresses. The term Parkinson’s disease dementia (PDD) refers specifically to the type of dementia associated with Parkinson’s disease. The main features of PDD include cognitive impairment, functional decline, and behavioral changes. Pathologically, PDD involves the accumulation of Lewy bodies and amyloid plaques in the brain. PDD can occur in the later stages of Parkinson’s disease and profoundly impacts quality of life. Management focuses on treating cognitive symptoms using medications like cholinesterase inhibitors.
Psychosis
Parkinson’s disease psychosis (PDP) refers to hallucinations and delusions that can occur in up to 60% of Parkinson’s disease patients, often later in the disease. PDP symptoms include visual hallucinations and delusions. The underlying cause involves dopamine dysregulation and Lewy body deposition in the brain. Reducing dopaminergic medications can help treat psychosis, but medications like quetiapine may also be used. PDP significantly increases caregiver stress and nursing home placement risk.
Sleep Disorders
Sleep disturbances are extremely common in Parkinson’s, affecting up to 98% of patients. Symptoms include insomnia, daytime sleepiness, restless leg syndrome, sleep apnea, and REM sleep behavior disorder. Parkinson’s disease disrupts the normal sleep cycle architecture. Loss of dopamine neurons likely underlies many sleep disorders in Parkinson’s. Treatment is aimed at managing individual symptoms, such as using CPAP for sleep apnea or dopamine agonists for restless leg syndrome. Good sleep hygiene practices are also recommended.
Insomnia
Insomnia, characterized by difficulties falling asleep or staying asleep, occurs in 60-90% of Parkinson’s disease patients. Insomnia correlates with disease severity. Contributing factors include motor symptoms, cramping, depression, anxiety, and medication effects. Management options for insomnia include sleep hygiene, cognitive behavioral therapy, light therapy, and medications like eszopiclone or doxepin. Addressing contributing factors like pain, bladder issues, and stress can also improve sleep.
REM Sleep Behavior Disorder
REM sleep behavior disorder (RBD) occurs in up to 60% of Parkinson’s disease patients, often preceding Parkinson’s diagnosis. RBD involves abnormal REM sleep muscle activity, resulting in vivid dreams and motor activity during sleep. Clonazepam or melatonin can help treat RBD symptoms. RBD appears to be associated with PD progression and cognitive decline. RBD diagnosis also represents a risk factor for eventually developing an alpha-synuclein disorder like Parkinson’s disease.
Autonomic Dysfunction
Autonomic nervous system dysfunction is common in Parkinson’s disease, causing various symptoms like orthostatic hypotension, constipation, urinary problems, sweating abnormalities, and sexual dysfunction. Dysfunction of the autonomic nervous system is due to alpha-synuclein deposition in peripheral autonomic nerves and brain regions that regulate autonomic function. Managing autonomic symptoms can significantly improve patient comfort and quality of life.
Orthostatic Hypotension
Orthostatic hypotension, defined as a sustained drop in blood pressure upon standing, affects 30-60% of Parkinson’s disease patients. Symptoms include lightheadedness, dizziness, and falls. Contributing factors include blood pressure regulation abnormalities and medications. Management focuses on hydration, gradual postural changes, compression garments, diet modifications and medication adjustments. Droxidopa or midodrine may be used for refractory orthostatic hypotension.
Gastrointestinal Issues
Gastrointestinal issues like constipation, dysphagia, and nausea affect the majority of Parkinson’s disease patients. Constipation occurs due to gut motility problems. Chewing and swallowing difficulties characterize dysphagia. Nausea is a medication side effect in some cases. Managing GI issues through diet, fluids, exercise, laxatives, medication changes or botulinum toxin injections can significantly improve comfort.
Motor Complications
Parkinson’s disease progression is associated with the development of motor complications like dyskinesias, fluctuations, and freezing of gait (FOG) that can significantly impact function and quality of life. Optimizing Parkinson’s disease treatment regimens can help reduce motor complications.
Dyskinesias
Dyskinesias are involuntary, erratic writhing movements affecting the face, arms, legs or trunk. Dyskinesias result from long-term levodopa therapy, affecting 30-50% of patients over time. Strategies for managing dyskinesias include adjusting medication timing and doses, adding amantadine or deep brain stimulation surgery in severe cases.
Fluctuations
Motor fluctuations refer to the alternating periods of good symptom control and poor symptom control as levodopa effects wear off. Symptoms “on” periods include improved mobility with reduced rigidity and tremor. “Off” periods have increased Parkinson’s symptoms. Motor fluctuations affect motor function, mood, cognition, and dyskinesias. Adjusting medication frequency, adding dopamine agonists or deep brain stimulation can help reduce fluctuations.
Freezing of Gait
Freezing of gait (FOG) involves brief episodes where patients are unable to step forward, increasing falls risk. FOG is associated with disease progression, longer disease duration, and cognitive decline. FOG management strategies include exercise, mobility aids, medication adjustments, and physical therapy. FOG significantly impacts independence and quality of life.
Falls and Frailty
Parkinson’s disease patients have a high risk of falls and increased frailty. Contributing factors include motor disabilities, decreased muscle strength, poor balance and cognition, orthostatic hypotension and medications. Consequences can include fractures, injury, fear of falling, and functional decline. Fall prevention strategies, exercise, home modifications, assistive devices and physical therapy can help reduce risk.
Fractures
Up to 40% of Parkinson’s disease patients experience fractures, most commonly involving the hip, pelvis, spine, wrist, humerus and femur. Fractures occur due to falls, muscle rigidity increasing impact forces, and osteoporosis. Fractures cause significant morbidity including pain, hospitalization, disability and increased mortality. Identifying and addressing risk factors like osteoporosis and fall hazards can help prevent fractures.
Frailty
Frailty is characterized by weakness, fatigue, weight loss, low activity, slow gait and cognitive impairment. Frailty increases with Parkinson’s disease progression, affecting 50% of patients after 8 years. Frailty is linked to poor nutrition, comorbidities, polypharmacy and sarcopenia. Exercise, nutrition, social engagement and treatment of contributing factors can help manage frailty and associated disability.
Pain
Pain is a prevalent non-motor symptom of Parkinson’s disease experienced by 60-85% of patients. Parkinson’s pain can be musculoskeletal, dystonic, central or neuropathic in nature. Commonly reported pains include shoulder, back and leg pain. Pain contributes to depression, sleep issues, and disability. Pain management options include physical therapy, heat, massage, exercise and medications if needed.
Musculoskeletal Pain
Musculoskeletal pain related to muscle rigidity, poor posture, osteoarthritis, and skeletal issues affects around 70% of Parkinson’s disease patients. Common pains involve the shoulders, neck, back, hips and legs. Managing musculoskeletal pain through exercise, physical therapy, assistive devices, hot/cold therapy, massage and analgesics provides symptom relief.
Dystonic Pain
Dystonic pain results from sustained involuntary muscle contractions causing abnormal postures like foot inversion or wrist flexion. Dystonia typically occurs with Parkinson’s progression or after long-term levodopa therapy. Botulinum toxin injections into affected muscles can treat focal dystonias. Adjusting medications and exercise can also provide some relief from dystonic pain.
Cognitive Changes
Parkinson’s disease involves cognitive changes in many patients spanning multiple domains including executive function, memory, visuospatial function and attention. Even early stage Parkinson’s often has mild cognitive impairment. Cognitive decline can progress to Parkinson’s disease dementia. Cholinesterase inhibitors may help treat Parkinson’s related cognitive impairment.
Executive Dysfunction
Impaired executive function involves difficulties with planning, organizing, multi-tasking, decision-making and regulation of emotions or behavior. Executive dysfunction correlates with reduced quality of life and caregiver stress. Cognitive rehabilitation therapy and cholinesterase inhibitors like rivastigmine may help improve function.
Memory Loss
Memory deficits in Parkinson’s can include impaired recall, recognition and episodic memory. Memory decline correlates with cholinergic denervation. Memory symptoms are managed through cognitive rehabilitation, written cues, medication reminders and cholinesterase inhibitors in some cases.
Sensory Changes
Parkinson’s disease patients can experience various sensory symptoms like pain, changes in vision, taste or smell that impact quality of life. Sensory problems likely stem from pathological changes in the central and peripheral nervous systems.
Vision Changes
Vision changes occur in around 60% of Parkinson’s patients and can include blurred vision, double vision, decreased contrast sensitivity and visual hallucinations. Dopaminergic therapy improves some visual symptoms. Managing changes through prescription adjustments, prism lenses, or cataract surgery can aid functioning.
Loss of Smell
Hyposmia, or reduced ability to smell, precedes motor Parkinson’s symptoms in some cases and eventually affects around 90% of patients. The underlying cause involves alpha-synuclein deposition and Lewy bodies in the olfactory bulb. Smell loss can lead to appetite and nutrition issues. No treatments are available currently to restore smell function.
Conclusion
Parkinson’s disease involves motor and non-motor symptoms that contribute to significant comorbidity burdens. Most patients have multiple comorbid conditions including psychiatric disorders, sleep disturbances, autonomic dysfunction, motor complications, cognitive changes, and sensory issues. Managing comorbidities through lifestyle modifications, therapy, and medication adjustments can optimize quality of life for Parkinson’s disease patients.