The impact of anxiety on conversion from mild cognitive impairment to Alzheimer's disease

Abstract

Objective: To compare state and trait anxiety in mild cognitive impairment (MCI) patients and matched control subjects, and to assess the impact of these variables in predicting conversion to Alzheimer's disease.

Methods: One hundred and forty-eight patients with MCI, broadly defined, were assessed and followed systematically. Baseline predictors for follow-up conversion to AD (entire sample: 39/148 converted to Alzheimer's disease (AD)) included the Spielberger State-Trait Anxiety Inventory (STAI).

Results: At baseline evaluation, MCI patients had higher levels of state and trait anxiety than controls, with no differences between future AD converters (n = 39) and non-converters. In age-stratified Cox proportional hazards model analyses, STAI State was not a significant predictor of conversion to AD (STAI State < or =30 vs. > 30 risk ratio, 1.68; 95% CI, 0.75, 3.77; p = 0.21), but higher Trait scores indicated a lower risk of conversion when STAI State, education, the Folstein Mini-Mental State Examination and HAM-D (depression score) were also included in the model (STAI Trait < or =30 vs. > 30 risk ratio, 0.36; 95% CI, 0.16, 0.82; p = 0.015).

Conclusions: In contrast to two other recent studies that showed anxiety predicted cognitive decline or conversion to AD, in this clinic-based sample, state anxiety was not a significant predictor. However, higher Trait anxiety predicted a lower risk of future conversion to AD. Further research with systematic long-term follow-up in larger samples is needed to clarify the role of state and trait anxiety in predicting MCI conversion to AD.