MEMORY deficit patterns are known to be associated with certain types of dementia. While retention-deficit in verbal learning tests is attributed to medial temporal lobe dysfunction, and commonly associated with Alzheimer’s disease (AD), retrieval-deficit is attributed to frontal lobe dysfunction, and associated with frontal-subcortical dementia.
Novel research presented at the 18th World Congress on Controversies in Neurology (CONy) aimed to determine whether memory deficit patterns (retention deficit amnestic mild cognitive impairment [MCI; rtn-aMCI] versus retrieval-deficit amnestic MCI [rtv-aMCI]) can discriminate amyloid-positive AD from amyloid-negative non-AD neurodegenerative diseases.
The study enrolled 174 patients with MCI between May 2016–April 2021, at the Department of Neurology at Kanbuk Samsung Medical Center, Seoul, South Korea. Subjects underwent neuropsychological assessments, brain MRI, and flutemetamol amyloid PET, and were diagnosed using the Petersen criteria for MCI. They were divided into rtn-aMCI (<-1.0SD on both delayed recall and recognition test) and rtv-aMCI (<-1.0SD on delayed recall, >-1.0SD on recognition test) based on the Seoul Verbal Learning Test (SVLT).
Of 174 patients, 106 were classified as rtn-aMCI (56.6% female; mean age: 72.87 years), and 68 were classified as rtv-aMCI (63.2% female; mean age: 74.59 years). The team found no significant difference in the number of patients with a positive β–amyloid PET scan between the two groups (50.0% in rtn-aMCI versus 47.1% in rtv-aMCI; χ2=0.143; P=0.705). Forward digit span (6.06±1.4 versus 5.25±1.6; P=0.001) and backward digit span (3.68±1.2 versus 3.29±1.4; P=0.05) were lower in the rtv-aMCI group. Word fluency and Stroop tests were not significantly different between the two groups.
The authors concluded that the temporal type memory deficit pattern in rtn-aMCI patients is not predictive of amyloid-positive AD. However, they highlighted that temporal type memory deficit can also be observed in various cognitive disorders other than AD.
