First, only a medical doctor or a neurologist can accurately diagnose what is going on with your loved one. Also, your primary care doctor may in fact refer you to a neurologist if you or your doctor thinks that it is appropriate.
Friends mean well, but it is only a professional who is trained in neurological disorders who can tell you more definitively. However, here is some information from the Northwest Parkinson’s Association which addresses this issue and describes other diseases which may have similar symptoms:
“The most recognizable syndrome, at least to the public eye, may be what George H.W. Bush has: vascular Parkinsonism, which is essentially clotting in the brain caused by mini strokes. Some other conditions include:
Lewy body disease. This is characterized by the early onset of dementia and cognitive dysfunction. People can also have hallucinations, which makes treatment difficult, since anti-psychotics used to treat hallucinations can worsen other Parkinsonism symptoms.
Progressive supra-nuclear palsy. Patients have early dementia, eye movement problems and a tendency to falls. They don’t have the resting tremor typical of Parkinson’s disease patients, but they do have stiffness and slowness, and they don’t respond to dopamine replacement therapy.
Corticobasal degeneration. One of the rarest conditions on the Parkinsonism spectrum, patients typically lose function on one side of their body, and they can develop alien limb syndrome, in which a limb does what it wants. They can also develop speech problems and jerky body movements.
Drug-induced Parkinsonism. Certain drugs, namely anti-psychotics, but also anti-nausea medications and some seizure medications, can cause Parkinsonism. Most Parkinsonism symptoms disappear after people stop taking the medications.
Multiple system atrophy. People with this condition sometimes look like they have problems with coordination; they may have problems with bowel and bladder function, adding that sometimes when they stand up, their blood pressure may drop, and they faint.”
I hope that gives you a little more information. But remember that each case is individual, and only a qualified professional can help determine if your loved one has PD.