Impaired information sampling in mild dementia of Alzheimer's type but not in healthy aging.

OBJECTIVE

It is unknown whether aging affects predecisional processing, that is, gathering information and evaluating options before making a decision. Here, we investigated information sampling in mild Dementia of Alzheimer's type (DAT) and healthy aging by using the Information Sampling Task (IST).

METHOD

In a first investigation, we compared patients with mild DAT (n = 20) with healthy controls (n = 20) on the IST and several neuropsychological background tests. In a second investigation, healthy older adults (n = 30) were compared with younger adults (n = 30) on the IST and executive-function tasks.

RESULTS

Results of the first investigation demonstrated that, in the IST, patients gathered significantly less information, made riskier and less accurate decisions, and showed less reward sensitivity relative to controls. We found a significant correlation between performance on the IST and performance on tests of verbal fluency, working memory, and recognition in patients but not in controls. Results of the second investigation indicated a largely similar performance pattern between healthy older adults and younger adults. There were no significant correlations for both groups between the IST and executive-function tasks.

CONCLUSIONS

There are no relevant changes with healthy aging in predecisional processing. In contrast, mild DAT significantly affects predecisional information sampling. Thus, the problems shown in patients with mild DAT in decision making might be related to the patients' difficulties in predecisional processing. Decision-making performance in mild DAT might be improved by helping the patients at a predecisional stage to gather sufficient information and evaluate options more accurately.