Sentence:  In other patients, the <WSD>dysthymia</WSD> may co-occur with but not be causally related to the ADHD (Adler and Cohen 2004)....Early studies of adults with ADHD found rates of <WSD>dysthymia</WSD> as high as 67%–81% (Wender et al. 1985). 
Meaning of the word marked with <WSD> tags:  A form of clinical depression, characterized by low-grade depression which lasts at least 2 years.