Clinicopathologic findings of argyrophilic grain dementia in a case of mild cognitive impairment converting to dementia

Abstract

An 84-year-old Japanese woman with no family history of dementia visited our memory clinic complaining of memory disturbance. Neurological examination revealed no apparent motor abnormalities, focal cerebral signs, parkinsonism, or cerebellar dysfunction. Hasegawa's Dementia Scale-Revised (HDS-R) and Mini mental state examination (MMSE) scores were 24 and 23 points, respectively. MRI revealed left-side-dominant dilatation of the inferior horn of the lateral ventricle. Although egocentric behavior was remarkable, no disturbance of intelligence was apparent at the first examination, and she was diagnosed as having mild cognitive impairment. Her memory disturbance and disorientation gradually worsened. Atrophy of the cerebrum and dilatation of the lateral ventricle advanced gradually on MRI. Two years later, she required care to perform activities of daily living. HDS-R and MMSE scores had dropped to 13 and 18 points, respectively, and conversion to dementia was diagnosed. Ability to perform 3D cube-copying was well preserved. The patient died due to acute myocardial infarction at the age of 87. The clinical diagnosis was Alzheimer disease. At autopsy, the brain weighed 1,250 g, and argyrophilic grains were widely observed in the limbic system, corresponding to Saito's stage III. Neuron loss, gliosis, spongiform change, and tissue rarefaction were recognized in the superficial layer of the parahippocampal gyrus. Ballooned neurons, pretangles, oligodendroglial coiled bodies, and neuropil threads were also observed. Neurofibrillary tangles and senile plaques, mainly consisting of diffuse plaque, were recognized as corresponding to Braak stage III and CERAD stage B, respectively. Neither Lewy nor Pick bodies were observed. Although mild phosphorylated TDP-43 immunoreactivity was observed, it was suspected to be due to secondary degeneration of tau deposition. The patient was diagnosed pathologically as having argyrophilic grain dementia. The clinical findings of the present patient reveal important observations that help to clinically discriminate between various dementias such as Alzheimer disease and argyrophilic grain dementia.