Fear acquisition and extinction in elderly patients with depression.

BACKGROUND: Depression in elderly patients is common and characterized by anxiety symptoms and cognitive impairment. To our knowledge, no studies have yet investigated the process of fear extinction in these patients. We investigated fear extinction with a paradigm consisting of habituation, acquisition and extinction. METHODS: We included three age matched (mean age: 75.7 years) groups: Late Life Depression (LLD, n = 33), Mild Cognitive Impairment (MCI, n = 39), healthy controls (HC, n = 39). All participants were diagnosed with a standardized procedure including clinical examination, CERAD cognitive test battery, as well as magnetic resonance imaging. Participants underwent a fear conditioning paradigm consisting of habituation, acquisition, and extinction. During acquisition, a neutral face (conditioned stimulus, CS+) was paired with an electrical unconditioned stimulus, whereas another face (safety stimulus, CS-) was unpaired. Conditioned responses were measured by US-expectancy and valence ratings. RESULTS: Compared to HC, both patient groups showed a significantly lower, differential (CS+ vs. CS-) fear acquisition across all measurements. Patients with cognitive impairment showed a significantly slower extinction, which is characterized by higher US-expectancy and reduced positive valence for CS+. Fear extinction was significantly less differential (CS+ vs. CS-) in patients with LLD. LIMITATIONS: Due to the cross-sectional design we cannot distinguish whether the observed differences in fear extinction are state or trait markers in the LLD patients. CONCLUSIONS: In this study, we demonstrate that fear extinction is impaired in elderly patients with depression. These results can have influence on treatment strategies.

Fear acquisition and extinction deficits in amnestic mild cognitive impairment and early Alzheimer's disease.

Impaired learning and memory functioning are prime markers for Alzheimer's disease (AD). Although initial evidence points to impaired fear acquisition in later AD, no study has investigated fear conditioning in early stages and amnestic mild cognitive impairment (aMCI), a condition often preceding AD. The present study examined if fear conditioning gradually decays from healthy elderly to patients with aMCI, to patients with AD. Patients with AD (n = 43), patients with aMCI (n = 43), and matched healthy controls (n = 40) underwent a classical fear conditioning paradigm. During acquisition, a neutral face (conditioned stimulus, CS+) was paired with an electrical stimulus, whereas another face (unconditioned stimulus, CS-) was unpaired. Conditioned responses were measured by unconditioned stimulus expectancy, valence, and skin conductance. Compared to healthy controls, both patient groups showed less differential (CS+ vs. CS-) fear acquisition across all measures. Patients further displayed slowed extinction indexed by higher unconditioned stimulus expectancy and reduced positive valence for CS+, declining from aMCI to AD. Groups did not differ in responses during a preconditioning habituation phase and in unconditioned responding. Diminished differential fear acquisition and slowed extinction could represent prognostic markers for AD onset.

Differences in psychological and somatic symptom cluster score profiles between subjects with Idiopathic environmental intolerance, major depression and schizophrenia.

Idiopathic Environmental Intolerance (IEI) has been associated with psychogenic factors and an increased number of comorbid psychiatric disorders such as depression and anxiety disorder. The purpose of the current study was to examine a possible overlap of psychological and somatic symptoms between subjects with IEI and patients with major depression and schizophrenia as well as to specify characteristic differences. The different symptom clusters included symptoms of chemical intolerance, neurotoxicity and psychological distress as well as measurements of mental health such as anxiety, depression, somatoform symptoms, and schizophrenia-specific disturbances in cognitive domains. IEI patients reported higher overall levels in physical symptoms such as chemical intolerance, neurotoxicity and somatic symptoms not attributable to an organic cause. Schizophrenia patients showed higher overall levels in self-experienced disturbances in several schizophrenia-specific cognitive domains, whereas general psychological distress, anxiety and depression were rated highest by patients with major depression. Importantly, the groups markedly differed in the shapes of profiles of various symptom clusters. Our results provide evidence that IEI patients can be distinguished on the phenomenological level from patients with major depression or schizophrenia, and that distinct domains of psychological and somatic symptoms are particularly problematic in specific diagnostic groups.