Non-motor symptoms of Parkinson's disease

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Non-motor symptoms in Parkinson's disease

Although the most obvious symptoms of Parkinson's affect movement, there is an increasing realisation in clinical practice that non-motor symptoms are at least as important in successful management. ^[1] Accurate diagnosis is made difficult by the overlap between organic symptoms of Parkinson's disease and non-motor symptoms, and it is becoming clear that without the use of objective measures, underdiagnosis is likely to occur. ^[2] For instance, a Parkinsonian individual with low energy, flat affect, and sexual dysfunction could easily be diagnosed as depressed, despite these symptoms resulting from their neurological disease rather than a mood disorder. Improving treatment of non-motor symptoms such as sleep disturbance and hallucinations could significantly improve quality of life for this group.

Depression in Parkinson's Disease

Depression is the most commonly occurring non-motor symptom in Parkinson's disease. It is well recognised in this disease, having been identified as "melancholia" by James Parkinson in his original report of the disease in 1817. It is thought to occur in about half of all cases (although major depression is rarer, ~8-17%) and is increasingly thought to be a consequence of the disease rather than an emotional reaction to disability. ^[3] What is called "depression" in this context may actually differ from depression that occurs in healthy people without Parkinson's disease. There is evidence that whilst the severity of depression in patients with Parkinson's disease can be as severe as that seen in primary mental health, it appears to be qualitatively different. For instance, in a recent study comparing neurologically healthy people with depression and Parkinson's patients with depression, the Parkinson's group reported less sadness, loss of pleasure, guilt, and less loss of energy. ^[4]

• anxiety or panic attacks
  Note: 70% of individuals with Parkinson's disease diagnosed with pre-existing depression go on to develop anxiety; 90% of Parkinson's disease patients with pre-existing anxiety subsequently develop depression);
• apathy or abulia: abulia [The patient is unable to act or make decisions independently.] It may range from subtle to overwhelming in severity.

translates from Greek as the absence or negative of will; apathy is an absence of feeling or desire

Cognitive disturbances:

• slowed reaction time; both voluntary and involuntary motor responses are significantly slowed.
• executive dysfunction, characterized by difficulties in: differential allocation of attention, impulse control, set shifting, prioritizing, evaluating the salience of ambient data, interpreting social cues, and subjective time awareness. This complex is present to some degree in most Parkinson's patients; it may progress to:
• dementia: a later development in approximately 20-40% of all patients, typically starting with slowing of thought and progressing to difficulties with abstract thought, memory, and behavioral regulation.
• memory loss; procedural memory is more impaired than declarative memory. Prompting elicits improved recall.
• medication effects: some of the above cognitive disturbances are improved by dopaminergic medications, while others are actually worsened ^[5]

Sleep disturbances:

• Excessive daytime somnolence;
• Initial, intermediate, and terminal insomnia;
• Disturbances in REM sleep: disturbingly vivid dreams, and REM Sleep Disorder, characterized by acting out of dream content;

Sensation disturbances

• Hallucinatons are found in about a quarter of Parkinson's disease patients. ^[6] They can occur in Parkinsonian syndromes for a variety of reasons. There is an overlap between Parkinson's disease and Lewy body dementia, so that where Lewy bodies are present in the visual cortex, hallucinations may result. Hallucinations can also be brought about by excessive dopaminergic stimulation. Most hallucinations are visual in nature, often formed as familiar people or animals, and are generally non-threatening in nature. Some patients find them comforting; however their carers often find this part of the disease most disturbing and the occurrence of hallucinations is a major risk factor for hospitalisation. Treatment options consist of modifying the dosage of dopaminergic drugs taken each day, adding an antipsychotic drug like quetiapine, or offering carers a psychosocial intervention to help them cope with the hallucinations. Many patients do not find the hallucinations a problem and so do not request treatment.

• Patients with Parkinson's disease have impairments in their ability to carry out a visual search. [1] This can have particular relevance when driving, and people with Parkinson's have been shown to be less accurate in spotting landmarks and roadsigns whilst driving. ^[7]

• impaired visual contrast sensitivity, spatial reasoning, colour discrimination, convergence insufficiency (characterized by double vision) and oculomotor control
• dizziness and fainting; usually attributable orthostatic hypotension, a failure of the autonomous nervous system to adjust blood pressure in response to changes in body position
• impaired proprioception (the awareness of bodily position in three-dimensional space)
• loss of sense of smell (anosmia),
• pain: neuropathic, muscle, joints, and tendons, attributable to tension, dystonia, rigidity, joint stiffness, and injuries associated with attempts at accommodation

Autonomic disturbances:

• oily skin and seborrheic dermatitis;
• urinary incontinence, typically in later disease progression
• constipation and gastricdysmotility: severe enough to endanger comfort and even health
• altered sexual function: characterized by profound impairment of sexual arousal, behaviour, orgasm, and drive is found in mid and late Parkinson disease. Current data addresses male sexual function almost exclusively.

References