Symbol Comprehension in Patients With Alzheimer Disease Dementia, Mild Cognitive Impairment, and Major Depressive Disorder

Abstract

Introduction: 

Previous research suggests that specific symbol features attenuate symbol comprehension deficits in seniors suffering from Alzheimer disease dementia (ADD). However, it remains unclear whether these findings also apply to other disorders associated with cognitive dysfunctions.

Methods: 

Ninety healthy controls, 30 patients with major depressive disorder (MDD), 35 patients with mild cognitive impairment (MCI), and 55 patients with ADD performed a Symbol Processing Task with 4 different symbol categories. Nonparametric between×within subjects analyses were conducted to examine the impact of different symbol categories on performance accuracy in all experimental groups.

Results: 

Analyses revealed a higher symbol comprehension accuracy in healthy seniors than in MDD, MCI, and ADD patients, with the lowest accuracy rates shown by ADD patients. Although the type of symbol hardly affected performance accuracy in healthy seniors and MDD patients, different symbol categories influenced the performance of MCI and ADD patients significantly.

Conclusions: 

Our findings indicate that symbols with distracting features impede symbol comprehension in ADD and MCI. Symbols with visual cues, by contrast, facilitate symbol comprehension in ADD and may even be advantageous over standardized symbols used in public life.