Awareness of cognitive impairment in individuals with essential tremor

Objective: The extent to which individuals with ET who have clinically significant cognitive impairment are aware of their cognitive changes is unclear. Reduced awareness has important implications for everyday function and decision-making.

Methods: 150 individuals with ET (109 Normal Cognition (ET-NC group), and 30 with MCI and 11 dementia (ET-CI group)) completed self-ratings and objective assessments of memory, language, and executive functioning. Discrepancy scores were calculated to assess awareness of cognitive functioning. One sample t-tests evaluated whether mean discrepancy scores in each group were comparable to zero (i.e., accurate). Analyses of covariance (ANCOVA) compared discrepancy scores across two groups controlling for age and education.

Results: In the ET-NC group, discrepancy scores for language (M=-0.08, SD=1.10) and executive functioning (M=-0.01, SD=0.99) were comparable to zero. Memory discrepancy scores (M=0.32, SD=1.22) were greater than zero. In the ET-CI group, memory, (M=0.78, SD=1.01), language, (M=0.46, SD=0.95), and executive (M=0.39, SD=1.14) discrepancy scores were all greater than zero. Discrepancy scores were larger in ET-CI group than in ET-NC group for memory: F(1,148)=4.02, p=0.047, language: F(1,148)=6.16, p=0.014, and executive: F(1,148)=4.51, p=0.035.

Conclusions: Individuals with ET and normal cognition accurately assessed their language and executive abilities, demonstrating mild overconfidence in memory function. Individuals with ET and cognitive impairment overestimated their performance in all domains of functioning. Since ET is linked to increased risk for cognitive impairment, and such impairment may not be accurately perceived, cognitive functioning should be proactively and regularly screened in ET.