Depression diagnosis was not related to processing speed, according to a recent study, however, depression symptom burden was, suggesting that how one defines depression matters when evaluating slowed processing speed in depressed individuals. Participants (n=223) were research volunteers who served in the US military since September 11, 2001, and denied a history of significant brain injuries. Depression was measured using a structured interview, the Personality Assessment Inventory (PAI), and the Beck Depression Inventory-II (BDI-II). Researchers found:

• There was not a consistent pattern of slowed processing speed in those with current depressive diagnoses compared to those without.
• However, depression symptom burden per the PAI Depression scale was significant for 7 of 10 processing speed tests.
• Only non-dominant fine motor dexterity was significantly slower in those with high vs low burden using BDI-II quartiles.
• Thus, the motor slowing hypothesis was supported, but only for depression burden and not diagnostic status or high vs low categorical classification.