Explain why anhedonia is specifically and routinely asked about in a depression assessment, rather than being assumed to be present whenever a patient reports low mood.

Anhedonia is one of the two core features at the heart of a depressive illness, alongside pervasive low mood, but patients often don't mention it spontaneously — they may not think to describe a lack of pleasure as a symptom, or may not have noticed the change until asked directly. Because it's so central to how the illness is actually affecting someone's day-to-day life, and because it can be present even when a person doesn't describe themselves as overtly sad, specifically probing for it, rather than inferring it from a low-mood report alone, is necessary to avoid missing it.