IBD in older individuals is actually very common
A Swedish national registry study of all 27,834 patients diagnosed with IBD in that country during 2006-2013 showed that 23% were first diagnosed at age 60 or older, with an incidence rate of 35 per 100,000 person-years for Crohn’s disease and 19 per 100,000 person-years for ulcerative colitis (Gastroenterology. 2018 Feb;154[3]:518-528e15.
“One in four to one in five of your new IBD patients are going to be over the age of 60. That’s pretty impressive,” Dr. Mahadevan said.
Genetics is less important in the pathophysiology of older-onset IBD. In one study, a positive family history of Crohn’s disease was present in 16% of affected patients under age 17 but in only 7% of those with disease onset after age 60. Similarly, a positive family history was present in 13% of ulcerative colitis patients under age 17 but in just 3% of those with onset after 60.
If genetics plays a minimal role in elderly-onset IBD, then what are the drivers? Two contributors are immunosenescence and age-related changes in the gut microbiota. Aging is accompanied by diminished T-cell responses marked by impaired memory T cells and a reduction in naive T-cell precursors.
“As the rest of you starts to age and sag, so do your T cells,” the gastroenterologist quipped.
Aging also brings physiologic alterations in gastrointestinal motility and transit. Together with changes in diet and an increase in comorbid conditions, with consequent need for a raft of medications, the end result is reduced abundance and diversity of anaerobes in the microbiota. This has immunologic implications.