Relationships between Environmental Dependency and Closing-in in Patients with Fronto-temporal Dementia

Environmental dependency (ED) phenomena, including utilization behavior and imitation behavior, are clinical manifestations typically observed in patients with the behavioral variant of fronto-temporal dementia (bvFTD), who may also show the closing-in (CI) phenomenon. Here, we explored the neuropsychological correlates of ED and CI in bvFTD, and the association of ED with CI to clarify the mechanisms underlying these clinical manifestations. Thirty-one bvFTD patients underwent a wide cognitive assessment in addition to special tasks to detect occurrence of CI and ED phenomena. Both ED and CI phenomena were present in more than half of the sample. Logistic regression analyses revealed that both ED and CI phenomena were significantly associated with poor scores on frontal neuropsychological tests. Although ED and CI often co-occurred, 3/12 patients with CI did not show ED, and 5/18 patients with ED did not show CI. A logistic regression model showed that the presence of ED was not significantly associated to CI. CI and ED are associated to progressive derangement of frontal functions in bvFTD. However, specific frontal dysfunctions might explain the occurrence of either phenomenon in isolation.