MAPT and Mental deterioration: However, given the small difference in cognitive decline between the A − T− and A − T + groups (e.g., d = 0.19 on episodic memory), compared to the larger difference in cognitive decline between the A + T − and A + T + groups without dementia (e.g., d = 0.26 on episodic memory), these results suggest that cognitive decline is amplified when abnormal tau occurs in the presence of extant amyloid plaque deposition [41–43].