Having a history with obsessive-compulsive disorder (OCD), I’ve long found it fascinating and, in a way, reassuring to read about the disorder’s many guises. The anxious thoughts and compulsive responses to them follow a common script, but the specifics vary. What seems horrible to one person with OCD, such as using a restroom without extensively washing their hands, might seem innocuous to the next person, who’s preoccupied by something completely different (such as worrying and repeatedly testing whether doors are locked, or having ‘bad thoughts’ and scrutinising what they mean). Reflecting on this merry-go-round of fears tells you something about the true nature of your specific, seemingly terrible fear.

A book I recently read showed me another dimension of this multiplicity – stretching it backward in time. In portions of Can’t Just Stop: An Investigation of Compulsions (2017), the late science journalist Sharon Begley surveys compulsions of the past. Based on rare historical accounts, she writes, it seems that ‘until the late seventeenth century, [compulsions] were seen as evidence of Satan’s hand and addressed by clergymen.’ Some of them featured the scrupulosity that still appears in many OCD cases today – for example, compulsively praying, fearing you’ve not done it right.

But other variants emerged in the record. A Renaissance-era physician described a patient who felt compelled to wash her clothes after touching things. Later, Begley writes, changes such as the spread of household stoves encouraged compulsive checking (eg, checking and rechecking whether you left the stovetop or oven on, a well-recognised pattern today). In what sounds a lot like an OCD compulsion, the 18th-century writer Samuel Johnson would reportedly touch each lamppost as he walked down the street, ensuring he didn’t miss any. The disorder took on new faces, and the explanations for it evolved. But its insidious power appears to be age-old.