"In another case, a woman treated for chronic pain was given direct control over her own device (this is not done currently). She wound up stimulating herself so often that she had heart problems and did little else for two years, essentially developing an addiction. She described the experience as “erotic” and began ignoring her family and failing to bathe. She pushed the button on the stimulator so frequently that she developed an open sore on the finger she used to press it. Interestingly, the 48-year-old had previously had a problem with alcohol and opioids."
https://www.vice.com/en_us/article/qj4d4w/brain-implants-to-treat-addiction-are-dangerous-and-promising
https://www.vice.com/en_us/article/qj4d4w/brain-implants-to-treat-addiction-are-dangerous-and-promising