I do know that for someone with cholesterol concerns this would be discouraged. This is the basis of the zone diet. The zone diet maintains a constant balance of protein and carbohydrates to prevent an over secretion of insulin. This drives the blood sugar down and then people feel hungry and want carbohydrates. My mother adds salt to everything she eats, I mean everything.
Salt causes a person to retain fluid which drives up the blood pressure.
For some people with PD a low blood pressure is common. When this low BP causes them to be dizzy or sleepy we encourage the liberal use of salt. As people age they loose some of their taste buds which can decrease appetite. Also just living alone, depression, mobility problems etc can make them more at risk of malnutrition. I think weight loss is the best guideline.