I live in an area of Canada where what you describe occurs with a lot of seniors. On investigation it was found that this was often exposure to low-level carbon monoxide poisoning. Seniors will often leave gas appliances unattended, not change furnace filters or maintain heaters, furnaces, etc. They also often will leave vehicles running or let pilot lights go out. Carbon monoxide poisoning can affect a person for up two years afterward. Elderly and particularly those with existing cardiace problems are even more likely to experience extreme shortness of breath and exacerbation of cardiac symptoms......not what you were thinking about but something you might investigate anyway.
Life....nobody gets out alive....so laugh and slam the door when you leave!