Understanding Neurology

Disorders of cognition 91CLINICAL SCENARIOSCASE 1A 66-year-old male presents to the Memory and Cognitive Disorders Clinic complaining that hismemory is failing. He has been troubled with this for a few months. He has been failing to keepappointments and finds it difficult to follow weekly TV series from one week to the next. He hasstarted using lists for the first time. He denies low mood. His wife has noted forgetfulness for over ayear. It was of insidious onset, and is progressing. He has become repetitive, and does not learn newinformation. He appears otherwise unchanged, with no alteration of personality.Insidious progressive forgetfulness is very suggestive of early dementia. Examples of his memoryproblems are of failing to keep appointments or to remember TV programmes from one week to thenext, i.e. true episodic memory deficit. The patient denies low mood, making depressivepseudodementia less likely. No early change in personality makes a frontal dementia unlikely.On bedside cognitive examination, he was oriented except for the date. Cognitive deficits wererestricted to memory. While immediate registration of name and address was normal, delayed recallwas poor at 0.Normal bedside cognitive testing with very poor delayed recall demonstrates a specific deficit ofepisodic memory. As definitions of dementia require impairment in at least two areas of cognition, heis not by definition demented. However, the very early changes of Alzheimer’s disease affect theperihippocampal areas, resulting in a pure amnesia initially. He thus is not demented, but hisprogressive amnesia is likely to be due to Alzheimer’s disease.Magnetic resonance imaging (MRI) showed bilateral hippocampal atrophy (83), while singlephoton emission computed tomography revealed bilateral temporo-parietal hypoperfusion (84). Hewas commenced on anticholinesterases.838483 Magnetic resonance image showing medialtemporal atrophy in Alzheimer's disease.84 Single photon emission computed tomography scanshowing temporo-parietal hypoperfusion in Alzheimer'sdisease.