Senescence Accelerates the Occurrence of Dual Amyloidosis: Alzheimer's Disease and Wild-Type Transthyretin Amyloidosis

TL;DR

An elderly man had both Alzheimer's disease and wild-type transthyretin amyloidosis, highlighting the possibility of dual amyloidosis in aging populations.

Contribution

This is the first reported case of concurrent Alzheimer's and ATTRwt amyloidosis diagnosed in life, not just at autopsy.

Findings

The patient had amyloid deposits in the brain and heart, confirmed by imaging and biopsy.

No genetic mutations in the TTR gene were found, supporting a diagnosis of wild-type amyloidosis.

The case suggests dual amyloidosis may be underdiagnosed in the elderly.

Abstract

We report a case of dual amyloidosis with Alzheimer's disease and wild-type transthyretin (ATTRwt) amyloidosis. A 76-year-old man with Alzheimer's disease was referred for anti-amyloid-β therapy with lecanemab. He also had symptoms of congestive heart failure and a history of carpal tunnel syndrome, cubital tunnel syndrome, and lumbar spinal stenosis; raising Technetium-99m pyrophosphate myocardial scintigraphy showed abnormal uptake, and histopathologic examination revealed transthyretin (TTR) amyloid deposition in both myocardial and gastrointestinal biopsy specimens. Genetic testing for the TTR gene revealed no variants. The diagnosis of ATTRwt amyloidosis was confirmed, and treatment with a TTR tetramer stabilizer, tafamidis, was initiated. Alzheimer's disease of the brain and ATTRwt amyloidosis of the heart are both representative amyloidoses associated with aging. To date, there are no reported cases of dual amyloidosis other than autopsy cases, but considering the high prevalence of both diseases, it is plausible that a significant number of elderly individuals may suffer from both diseases simultaneously but are underdiagnosed. In recent years, disease-modifying drugs effective against both diseases have become available, making early diagnosis increasingly important.

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