America’s 78 million aging baby boomers are heading into retirement with more than their considerable wealth, health and education. They are also bringing into their golden years an epidemic of drug and alcohol abuse and mental illness that has yet to be recognized, according to a recent Institute of Medicine report.

The notion that the elderly might be abusing or addicted to alcohol, illicit drugs or prescription medications may strike some as improbable. After all, the common notion is that alcohol and substance abuse are for young people.

Dead wrong. Baby boomers, who came of age in the ’60s and ’70s when experimenting with drugs was pervasive, are far more likely to use illicit drugs than previous generations. For example, a 2011 study by the Substance Abuse and Mental Health Services Administration found that among adults aged 50 to 59, the rate of current illicit drug use increased to 6.3 percent in 2011 from 2.7 percent in 2002. Aside from alcohol, the most commonly abused drugs were opiates, cocaine and marijuana.

To get a sense of the magnitude of this looming mental health crisis, consider that in 2010 the best estimates are that six to eight million older Americans - about 14 percent to 20 percent of the overall elderly population - had one or more substance abuse or mental disorders. The number of adults aged 65 and older is projected to increase to 73 million from 40 million between 2010 and 2030, and the numbers of those needing treatment stands to overwhelm the country’s mental health care system.

Detecting drug or alcohol problems in the elderly is difficult in part because family members and clinicians alike are reluctant to ask about it. Perhaps it’s just a form of ageism, but drug abuse is not the first thing that pops into the mind of physicians when they encounter an older patient.

Even when they make the connection, doctors may fail to realize that even modest amounts of alcohol or drugs can be problematic. Older patients have a significantly reduced ability to metabolize these substances, as well as increased brain sensitivity to them. And the cognitive impairments common with advancing age make self-reporting - as well as self-monitoring - unreliable.

Not long ago, a medical colleague referred a 67-year-old woman to me with mild depression, weakness and complaints of short-term memory loss. Her physician told her there was no clear medical explanation for her symptoms, given that her physical exam, exhaustive lab tests and brain M.R.I. were all normal.

The problem, I soon discovered, was that her alcohol consumption had tripled since the death of her husband a year earlier. She did disclose to her internist that she drank but minimized the amount. She had turned to alcohol, self-medicating her grief, but it only worsened her mood and impaired her memory, typical of alcohol’s effects on the brain.

Numerous surveys document problematic drinking among the elderly. For example, a 2011 National Survey on Drug Use and Health found that 8.3 percent of adults 65 and older reported binge drinking, defined as having four or five drinks on one occasion in the past month, while the rate of heavy drinking was 2 percent.

Given the increased sensitivity to the harmful effects of alcohol with aging, the National Institute of Alcohol Abuse and Alcoholism recommends that men and women aged 65 or older have no more than three drinks on any day and no more than seven drinks per week. (If you are curious if you might have a drinking problem, you can take a quick screening test called the MAST-G.)

Although alcohol is clearly the most commonly abused drug in the elderly, nonmedical use of prescription drugs is a rapidly growing threat. Some studies estimate that up to 10 percent of the elderly misuse prescription drugs with serious abuse potential, most often anti-anxiety benzodiazepines like Klonopin, sleeping pills like Ambien and opiate painkillers like Oxycodone. Women far outnumber men when it comes to nonmedical use of prescription medication: 44 percent of women versus 23 percent of men.

The elderly rarely use alcohol or drugs to “get high”; drug or alcohol use that begins after age 60 appears fundamentally different. Typically, those who start use as teenagers or young adults tend to be sensation-seekers with significant rates of psychiatric disorders and antisocial traits. In contrast, the elderly turn to alcohol and drugs to alleviate the physical and psychological pain from the onslaught of medical and psychiatric illness, the loss of loved ones or social isolation.

The problem is that these psychoactive drugs are all addicting and can impair cognitive functioning, cause depression, increase the risk of falling and interact dangerously with other medications. Moreover, drug and alcohol abuse in older patients occurs alongside other medical and psychiatric illnesses. You cannot treat either problem in isolation.

There is little doubt that we face a looming public mental health crisis in the aging population. The question is whether we can meet this daunting challenge with the investment in research and mental health services it deserves.

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By RICHARD A. FRIEDMAN, M.D.