How do specialists tell ADHD inattentiveness apart from depression fog?

Clinicians look at timing, consistency, and context. ADHD inattention is usually lifelong, fluctuates with interest, and improves with structure or stimulation. Depression related fog often comes with low mood, reduced pleasure, and global slowing. They also assess which symptoms came first and how they respond to treatment. It is very common for both to coexist, and teasing them apart takes careful history rather than a single question or test.