Review Question - QID 106112

This patient's short-term memory loss in the absence of other symptoms is consistent with Alzheimer's Disease (AD). Intracellular neurofibrillary tangles consisting of hyperphosphorylated tau protein are a histologic finding of AD.

Alzheimer's Disease is the most common cause of dementia occurring in old age. AD classically presents with short-term memory loss which progresses to long-term memory loss, disorientation, and behavioral and personality changes. While AD is primarily a diagnosis of exclusion, it can be confirmed through post-mortem histologic findings of extracellular Aß-amyloid plaques and intracellular neurofibrillary tangles consisting of hyperphosphorylated tau protein. Notably, these intracellular tangles correlate with the degree of dementia.

Cummings et al. describe the management of patients with AD from the perspective of a general medicine or family medicine practitioner. Routine evaluation involves assessment of cognitive status and ability to perform activities of daily living (ADLs). This can be done using standardized instruments such as the Mini-Mental State Examination (MMSE) and the ADL assessment form. Early identification of a primary caregiver is essential, as well as ensuring that the caregiver has an adequate support system and the resources to manage care for the patient.

Tan et al. compare the effectiveness of a number of pharmacological agents used to treat AD in a meta-analysis. Donepezil, galantamine, and rivastigmine are cholinesterase inhibitors which function by inhibiting the degradation of acetylcholine in the brain. Memantine is an NMDA receptor antagonist. All of these agents were found to have significant cognitive effects, though donepezil was not found to have an effect on function and memantine did not have an effect when assessed using the Clinicians' Global Impression of Change scale. In addition, memantine had less adverse events when compared to the anticholinesterase inhibitors.

Illustration A shows the histological appearance of Aß-amyloid plaques in the cerebral cortex of an individual with AD.

Incorrect Answers
Answer 1: Round intracellular tau protein aggregates are seen in Pick's disease. Pick's disease typically presents with personality changes including disinhibition and paranoia.
Answer 2: Intracellular alpha-synuclein aggregates, called Lewy bodies, are seen with Parkinson's disease and Lewy body dementia. Parkinson's disease typically presents with a resting tremor, slowed movement, and postural rigidity. Lewy body dementia presents with visual hallucinations, REM sleep abnormalities, and the motor features seen in Parkinson's disease.
Answer 3: Discrete, eosinophilic intracellular inclusions known as Negri bodies are seen with rabies. Rabies is transmitted via scratches or bites from infected animals. Symptoms usually develop 2-12 weeks after infection, and progress from flu-like symptoms to behavioral changes, paralysis, hallucinations, and hydrophobia.
Answer 5: AL amyloid deposition is seen with systemic amyloidosis classically secondary to multiple myeloma. Multiple myeloma is a malignancy characterized by abnormal proliferation of antibody-producing plasma cells. Symptoms include bone pain, anemia, and renal failure.