Background: Alzheimer's disease (AD) is clinically heterogeneous, including the classical-amnesic (CA-) phenotype and some variants.Objective: We aim to describe a further presentation we (re)named confabulation-misidentification (CM-) phenotype.Methods: We performed a retrospective longitudinal case-series study of 17 AD outpatients with the possible CM-phenotype (CM-ADs). Then, in a cross-sectional study, we compared the CM-ADs to a sample of 30 AD patients with the CA-phenotype (CA-ADs). The primary outcome was the frequency of cognitive and behavioral features. Data were analyzed as differences in percentage by non-parametric Chi Square and mean differences by parametric T-test.Results: Anterograde amnesia (100%) with early confabulation (88.2%), disorientation (88.2%) and non-infrequently retrograde amnesia (64.7%) associated with reduced insight (88.2%), moderate prefrontal executive impairment (94.1%) and attention deficits (82.3%) dominated the CM-phenotype. Neuropsychiatric features with striking misidentification (52.9%), other less-structured delusions (70.6%), and brief hallucinations (64.7%) were present. Marked behavioral disturbances were present early in some patients and very common at later stages. At the baseline, the CM-ADs showed more confabulation (p < 0.001), temporal disorientation (p < 0.02), misidentification (p = 0.013), other delusions (p = 0.002), and logorrhea (p = 0.004) than the CA-ADs. In addition, more social disinhibition (p = 0.018), reduction of insight (p = 0.029), and hallucination (p = 0.03) persisted at 12 months from baseline. Both the CA- and CM-ADs showed anterior and medial temporal atrophy. Compared to HCs, the CM-ADs showed more right fronto-insular atrophy, while the CA-ADs showed more dorsal parietal, precuneus, and right parietal atrophy.Conclusion: We described an AD phenotype resembling diencephalic rather than hippocampal amnesia and overlapping the past-century description of presbyophrenia.

Diencephalic versus Hippocampal Amnesia in Alzheimer's Disease: The Possible Confabulation-Misidentification Phenotype / Abbate, Carlo; Trimarchi, Pietro D; Fumagalli, Giorgio G; Gallucci, Alessia; Tomasini, Emanuele; Fracchia, Stefania; Rebecchi, Isabella; Morello, Elisabetta; Fontanella, Anna; Parisi, Paola M R; Tartarone, Federica; Giunco, Fabrizio; Ciccone, Simona; Nicolini, Paola; Lucchi, Tiziano; Arosio, Beatrice; Inglese, Silvia; Rossi, Paolo D. - In: JOURNAL OF ALZHEIMER'S DISEASE. - ISSN 1387-2877. - 91:1(2023), pp. 363-388. [10.3233/JAD-220919]

Diencephalic versus Hippocampal Amnesia in Alzheimer's Disease: The Possible Confabulation-Misidentification Phenotype

Fumagalli, Giorgio G;
2023-01-01

Abstract

Background: Alzheimer's disease (AD) is clinically heterogeneous, including the classical-amnesic (CA-) phenotype and some variants.Objective: We aim to describe a further presentation we (re)named confabulation-misidentification (CM-) phenotype.Methods: We performed a retrospective longitudinal case-series study of 17 AD outpatients with the possible CM-phenotype (CM-ADs). Then, in a cross-sectional study, we compared the CM-ADs to a sample of 30 AD patients with the CA-phenotype (CA-ADs). The primary outcome was the frequency of cognitive and behavioral features. Data were analyzed as differences in percentage by non-parametric Chi Square and mean differences by parametric T-test.Results: Anterograde amnesia (100%) with early confabulation (88.2%), disorientation (88.2%) and non-infrequently retrograde amnesia (64.7%) associated with reduced insight (88.2%), moderate prefrontal executive impairment (94.1%) and attention deficits (82.3%) dominated the CM-phenotype. Neuropsychiatric features with striking misidentification (52.9%), other less-structured delusions (70.6%), and brief hallucinations (64.7%) were present. Marked behavioral disturbances were present early in some patients and very common at later stages. At the baseline, the CM-ADs showed more confabulation (p < 0.001), temporal disorientation (p < 0.02), misidentification (p = 0.013), other delusions (p = 0.002), and logorrhea (p = 0.004) than the CA-ADs. In addition, more social disinhibition (p = 0.018), reduction of insight (p = 0.029), and hallucination (p = 0.03) persisted at 12 months from baseline. Both the CA- and CM-ADs showed anterior and medial temporal atrophy. Compared to HCs, the CM-ADs showed more right fronto-insular atrophy, while the CA-ADs showed more dorsal parietal, precuneus, and right parietal atrophy.Conclusion: We described an AD phenotype resembling diencephalic rather than hippocampal amnesia and overlapping the past-century description of presbyophrenia.
2023
1
Abbate, Carlo; Trimarchi, Pietro D; Fumagalli, Giorgio G; Gallucci, Alessia; Tomasini, Emanuele; Fracchia, Stefania; Rebecchi, Isabella; Morello, Elis...espandi
Diencephalic versus Hippocampal Amnesia in Alzheimer's Disease: The Possible Confabulation-Misidentification Phenotype / Abbate, Carlo; Trimarchi, Pietro D; Fumagalli, Giorgio G; Gallucci, Alessia; Tomasini, Emanuele; Fracchia, Stefania; Rebecchi, Isabella; Morello, Elisabetta; Fontanella, Anna; Parisi, Paola M R; Tartarone, Federica; Giunco, Fabrizio; Ciccone, Simona; Nicolini, Paola; Lucchi, Tiziano; Arosio, Beatrice; Inglese, Silvia; Rossi, Paolo D. - In: JOURNAL OF ALZHEIMER'S DISEASE. - ISSN 1387-2877. - 91:1(2023), pp. 363-388. [10.3233/JAD-220919]
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