Last week, as millions of Americans gathered with family at Thanksgiving, denial was a guest at many tables.

There were unspoken observations and quiet worry about some of those sitting down for the meal — maybe a returning veteran who is anxious and hard-faced, a promising nephew who can’t tell what is real or imagined, and Aunt Sue, whose slurred words and ever-present wine glass have become routine.

About one in five Americans suffers from mental illness and substance abuse. But despite its widespread impact, mental health is more often than not ignored, or misunderstood to be something that can not be treated as effectively as physical illnesses.

Recently we’ve been witnesses to the public pain, horror and tragedy linked to mental illness — Miriam Casey, who rammed her car into the White House barricades, Austin “Gus” Deeds, who stabbed his father, Virgina State Senator Creigh (Cray) Deeds, and killed himself, and Adam Lanza, who methodically planned the killing of 26 children and adults in the Sandy Hook school.

Treatment has proven effective. Earlier diagnosis, better drugs, and innovative psychotherapy have helped many. But, ongoing treatment is often out of reach or unaffordable. Insurance companies have differentiated between how medical and mental health illnesses are covered, with higher out of pocket costs for mental health therapies.

Mental health advocates thought that would change five years ago when President George Bush signed the Mental Health Parity Act, forcing insurance companies to reimburse for medical and surgical costs the same as they do for mental illness and addiction services. But insurers have delayed implementation of the law. New rules issued last month by the Obama administration are now requiring insurers to document compliance. That should make a difference.

Massachusetts already bolstered the federal parity law with state legislation requiring detailed reports, including information about how many times insurers deny or approve mental health coverage.

Only 60 percent of those who need mental health care get it now; these new rules will go a long way toward improving access.

That’s progress, I know, but an equally important step is removing the stigma of mental illness. So this holiday season we should retire the jokes about crazy Uncle Joe, and instead offer support to a loved one who may be silently suffering from serious yet invisible wounds.