Diverticular disease (DD) can progress from changes in the gut nerves and muscles to formation of diverticula (diverticulosis), to symptoms of colon dysfunction, to infections and inflammation (diverticulitis), to chronic symptoms, and to serious abdominal complications. The number of sufferers along this pathway diminishes greatly at every stage, only a minority ever need surgical treatment. On the other hand, progression and ageing go hand in hand.
The causes and risk factors of progression after diverticulosis are as varied as the people with DD. Nobody knows what brings on diverticulitis which can be a gateway to problems. Historically, a diet low in fibre was thought to be responsible for all of the disease spectrum and could be easily remedied. This is no longer accepted. In the second half of the 20th century nobody considered an effect of smoking on the gut. Most Western adults smoked despite the risks of lung cancer and heart disease. Cigarettes had calmed the soldiers of the war, they were glamorous and macho, and nicotine was strongly addictive.
Cigarette use was aligned much closer to the appearance of DD in the world than diets which were variable and often assumed. Articles on this website in 2012 and 2013 have details of this epidemiology and also explain the pharmacology of nicotine where chronic use can cause the damage to the colon characteristic of DD.