When a widely publicized landmark study of the sexual habits of older adults was recently published in The New England Journal of Medicine, many people were shocked by the results. University of Chicago researchers who asked 3,000 adults nationwide about their sex lives found that the majority of sexually active adults in their 50s, 60s, 70s and 80s were having sex two or three times a month or more -- the same rate as people in their 20s, 30s and 40s.

But the survey also found that many older adults are not sexually active -- and many who are having sex are not sexually satisfied. Why not? There are various reasons...

MEDICATIONS

Older adults typically take the most medications -- and many have sexual side effects.

The biggest offenders...

Antidepressants. Selective serotonin reuptake inhibitors (SSRIs), such as citalopram (Celexa), sertraline (Zoloft) and fluoxetine (Prozac), can cause sexual difficulties, including ED, delayed ejaculation and decreased sexual desire.

Trap: Among the SSRIs, Prozac has one of the highest incidence rates for sexual difficulties -- but it is frequently prescribed because it has a good track record... is available in a generic form, which is less expensive than a brand-name antidepressant... and is likely to be covered by insurance. 

Better: Talk to your doctor about taking an SSRI other than Prozac. If you still have sexual difficulties after switching SSRIs, consider taking half the dosage and adding bupropion (Wellbutrin), an antidepressant that rarely causes sexual side effects. (In some cases, people who take bupropion alone experience a worsening of anxiety disorders.) 

CHRONIC ILLNESS

Chronic diseases, such as heart disease and cancer, are more common among older adults -- but they don’t necessarily have to derail sexual activity.

Cancer. In a 2007 study by Australian researchers, 80% of the partners of cancer patients said the diagnosis negatively impacted their sexual relationship.

Examples: A cancer patient may feel less sexually attractive if chemotherapy causes hair loss. A man may develop ED after surgery for prostate cancer.

What to do: If cancer is diagnosed, the patient and partner should talk to a doctor about their sexual relationship -- asking questions and having them answered in an unrushed atmosphere. According to research, this approach usually leads to positive sexual experiences -- in spite of cancer.