Published on: May 22, 2017
by Women’s Brain Health Initiative:
Parkinson’s disease (PD) is a neurodegenerative disorder, meaning that it involves progressive loss of the structure or function of neurons (cells that transmit nerve impulses). It is the second most common neurodegenerative disorder after Alzheimer’s disease and other dementias. PD is characterized by movement dysfunction—for instance, tremor, impaired balance, slowness and stiffness—as well as cognitive and other non-motor impairments such as dementia, depression, insomnia, problems with handwriting and constipation.
Different people will experience different symptoms, in varying order and with varying intensity.
The disease develops over many years, as the brain slowly stops producing dopamine, a neurotransmitter that carries signals between the brain’s nerve cells. The disease itself is not fatal, and unfortunately there is currently no cure.
More men are diagnosed with Parkinson’s disease than women. A large meta-analysis conducted by Elbaz et al. published in the Journal of Clinical Epidemiology in 2002 found that in any given time period, twice as many men have PD than women. This difference in prevalence rates is just the tip of the iceberg, though. There are many more differences between women and men when it comes to Parkinson’s disease, including differences in age of onset, symptoms and treatment.
Differences in Age of Onset & Symptoms
The age of onset of Parkinson’s disease tends to be about two years later in women than in men. Among women, tremor is usually the primary symptom evident when they are diagnosed, whereas in men, the dominant initial symptom is usually bradykinesia (slow or rigid movement).
Women are more likely than men to experience constipation, pain, dyskinesias (difficulty with voluntary movement), and difficulties with daily activities such as walking and getting dressed. Men, on the other hand, are more likely to experience daytime sleepiness, drooling, sex-related symptoms, rigidity, and rapid eye movement behaviour disorder (a sleep disorder in which the person physically acts out their dreams).
There are differences in cognitive symptoms as well, with men more likely to have deficits in verbal fluency and recognition of facial emotion, while women are more likely to experience reduced visuospatial cognition —the skills that allow visual perception of objects and the spatial relationships between them.
Women and men also seem to differ in how they respond to living with Parkinson’s disease. Men are more likely to exhibit challenging behaviours such as wandering, and physical or verbal abuse. Conversely, women tend to experience more distress because of their PD symptoms (i.e. they are more likely to be anxious or depressed).
Differences in Treatment
Men with PD are more likely to be prescribed antipsychotic medication while women are more likely to be prescribed antidepressants — not surprising given their differing responses to PD as noted previously.
Women and men appear to respond differently to PD medication. The effectiveness of PD drugs may vary between women and men, and of particular concern is evidence that suggests women are more susceptible to negative side effects such as dyskinesia.
Women with PD are less likely than men to see a neurologist, despite studies showing that this can significantly improve care.
When women do see a neurologist, they tend to do so after a longer period of time post-diagnosis than men.
Women have surgery as part of their PD treatment less often than men, and they tend to have more severe symptoms by the time they undergo surgery.
Why These Differences Exist
The primary focus of research into the major factors affecting sex differences in PD has been on the role of sex hormones, mostly looking at the potential neuroprotective effects of estrogen in females. Several studies suggest estrogen has a neuroprotective effect on dopamine systems and helps reduce the risk of PD.
Lifestyle differences are also thought to contribute to men’s apparent increased risk of developing Parkinson’s disease. For instance, men may have increased risk because of exposure to toxicants (e.g., men are more likely to work with herbicides) or head trauma (which is more common in men).
Genetics, inflammation, and stress have also been suggested as factors that may also play a role in the sex differences noted with Parkinson’s disease.
More research is needed to better understand why these female-male differences exist. In particular, more clinical studies involving female participants are required. Currently, men with PD are studied more often than women with PD, in numbers that are disproportionate to the male-to-female prevalence ratio for the disease. Research on sex differences is crucial because it can inform treatment and care of those living with PD, for instance by aiding in accurate early diagnosis in both women and men (even if their initial symptoms differ) and by developing effective, but perhaps differing, courses of treatment.
Currently, there are two surgical treatments available for people living with Parkinson’s disease — deep brain stimulation (DBS) and surgery performed to insert a tube in the small intestine, which delivers a gel formulation of carbidopa/levodopa (Duopa™), the drug used to treat the motor symptoms of PD.
Source: MIND OVER MATTER
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