I would reassure your father that just because his father had Parkinson’s disease, that doesn’t mean he is destined to develop it, too. Everyone has approximately a 1 percent lifetime risk of developing Parkinson’s disease. If you have a first degree relative with Parkinson’s, then your lifetime risk is three times as high, or 3 percent—which is a 97 percent chance of not developing the disease.
While there’s great variability with Parkinson’s disease, we do know that there are certain signs that may appear well before the more commonly known physical symptoms—tremors, stiffness, and loss of dexterity.
For example, constipation is a very common problem for people with Parkinson’s disease, and a lot of people develop constipation months or sometimes even years before they develop the motor symptoms of Parkinson's disease.
Another common phenomenon that precedes the onset of the motor symptoms is a loss of sense of smell. Of course, this alone is not uncommon in older people, especially those who smoke or have a history of smoking. But when we ask patients with Parkinson’s about problems smelling, most people will say that they’ve noticed a problem with their sense of smell, as well as their sense of taste, for a couple of years prior to being diagnosed.
Probably the most significant early symptom of Parkinson’s disease is a change in a person’s sleep pattern. Virtually everyone with Parkinson’s disease will have some trouble with sleep, but it’s not general insomnia. It’s a specific problem called REM behavior disorder, or RBD. What this means is that the architecture of sleep changes, and people spend more time sleeping in the REM stage of sleep, which is when we dream. This leads to excessive dreaming, and in many cases these dreams are accompanied by vocalizations and movements during sleep. Sometimes, a patient’s bedmate may even get hurt by the person’s excessive movements during sleep. These sleep changes also begin about a year or two (or even more) before someone develops the physical symptoms of Parkinson’s disease.
A Parkinson’s diagnosis is usually made only after a patient develops physical symptoms, and these typically start on just one side of the body. A tremor in the arm or hand is probably the most revealing sign of Parkinson’s, but about 40 percent of patients never develop a tremor. The first motor symptoms to appear are usually a little stiffness or achiness on one side of the body, typically in the arm. By then, there is usually a little bit of loss in dexterity, as well.
So if your father is beginning to notice motor symptoms like stiffness, loss of dexterity, or a tremor, and has a history of the earlier symptoms mentioned above, I would encourage him to talk to his doctor and ask for a referral to a neurologist so that he can be evaluated.
The earlier someone is diagnosed and begins treatment, the sooner they can improve their quality of life and avoid complications.