The issue hasn’t received much attention in the mainstream media — but it could in the weeks ahead, thanks to a series of highly revealing videos and photographs that appear to show Clinton in various states of illness and incapacitation while campaigning on the stump.

Lingering concerns about Clinton’s health go back to her highly-publicized fall while traveling overseas as Secretary of State in late 2012.  Clinton suffered a concussion that also produced a life-threatening blood clot located near her brain.  Her doctors at the time warned that Clinton’s clot problem could easily recur, with attendant complications.

Some analysts — mostly conservative bloggers — speculate that Clinton’s clot may have caused additional neurological and nerve damage.  Combined with the effects of stress, aging (Clinton is 68), and poor dietary and exercise habits, it may left her vulnerable to chronic illness.  While the former First Lady sometimes references mind-body health practices like yoga there is no evidence that she engages in regular “fitness” activities.

The growing photographic and video evidence of Clinton’s health problems, while not conclusive, is certainly compelling.  It includes:

• Apparent seizures she’s suffered on the campaign trail, including highly-publicized incidents such as this one from July 2016.
• The documented appearance of a Secret Service “handler” at her side armed with an anti-seizure “diazepam pen,” apparently to ward off panic attacks and other potentially embarrassing episodes.
• Prolonged coughing fits while speaking to audiences — in some cases lasting nearly two minutes.
• A large circular lesion on her tongue typical of someone suffering from syphilis, HPV or tongue cancer.
• Pronounced bulges under clothing indicating the likely presence of a special medical device, possibly a defibrillator vest.
• An inability to perform routine physical activities, including the climbing of stairs, without active support from others.

Clinton supporters have pushed back against these claims, suggesting that they are part of the same conservative media conspiracy that has dogged the candidate for years.  Some argue that her health problems, if real, are little cause for concern because she has an “infrastructure” in place to ensure that her administration continues to function smoothly in the event of her absence.

Clinton herself may have fueled speculation about her health status when she insisted during her running mate search that her prospective VP should have significant national security experience and be ready to assume the presidency “on day one.”   Her seeming insistence on this point – and eventual choice of Virginia senator Tim Kaine, who serves on the foreign affairs and armed services committees – may have reflected an underlying concern about her vulnerability to persistent illness.

What conditions might Clinton be suffering from?  Her latest critic, controversial pharmaceutical executive Mark Shrkeli, says Clinton’s apparent seizures, trouble walking, and periodic inability to control her facial expressions are likely symptoms of early onset Parkinson’s disease.  He’s even speculated that she’s taking the drug which his own company produces to try to control these symptoms.

Clinton wouldn’t be the first presidential candidate to suffer from some kind of debilitating disease.  Franklin Roosevelt had polio for most of his life and his staff went to great lengths to conceal his condition from the public, fearing that it would undermine his popularity. And in 2011, reports surfaced that GOP presidential candidate Michele Bachmann suffered from severe migraines and fainting spells at a time when she was leading the Republican field, leading to demands from rivals that she immediately release her medical records.

Some critics felt those charges against Bachmann – based largely on hearsay from disgruntled ex-aides – were blatantly sexist – a throwback to the Victorian era when women of privilege were routinely portrayed as the “weaker” sex.  Partly for this reason, mainstream news organs are likely to tread carefully with Clinton unless more obvious signs of incapacity emerge.

But with Trump on the defensive, she may not get so lucky.  The two candidates have already accused each other of being “mentally unstable” and even “crazy.”   If Trump fears he’s in danger of losing the race, he may well decide to pull out all the stops.   And charges that Clinton’s lying about her health might resonate with voters – especially independents — already concerned about her penchant for deception generally.

As Bachmann discovered to her chagrin, it hardly matters whether your health problems are severe enough to call into question your qualifications and capacity to lead.  Unflattering publicity about them can plant pernicious doubts that may prove subtly damaging to your candidacy.