The Association Between Somatic Symptom Disorders and Neurocognitive Disorders: A Systematic Review

Onset of neuropsychiatric symptoms in older adults may represent prodromal manifestations of neurodegenerative disorders. The association between the onset of somatic symptom and related disorders (SSRD) and the subsequent development of neurodegenerative disorders remains unclear. A critical review of studies describing the association between SSRD and neurodegenerative disorders, such as Alzheimer's disease, Parkinson's disease, Frontotemporal dementia, and Lewy body dementia was performed.

To critically review studies describing the association between SSRD and neurodegenerative disorders, such as Alzheimer's disease, Parkinson's disease, Frontotemporal dementia, and Lewy body dementia.

A systematic review of Web of Science Core databases was carried out from inception of databases up to May 2021 to identify observational studies pertaining to both SSRD and neurodegenerative disorders. Data was extracted and compiled regarding subjects enrolled, age at onset of the SSRD and at onset of the neurodegenerative disorders, and specific SSRD manifestations and underlying neuropathologies reported.

Thirteen articles were included. Of the 123 identified subjects with SSRD at baseline, 34.1% developed a neurodegenerative disorder, with 80.9% of these being a Lewy body spectrum disorder. The interval between onset of SSRD manifestations and subsequent development of a neurodegenerative disorder was less than 3 years for half of the cases. Of the 1,494 subjects with a neurodegenerative disorder at baseline retrieved, SSRD manifestations were reported in 33.4% of Lewy body spectrum disorders cases. Onset of SSRD manifestations antedated or was concomitant to the diagnosis of the Lewy body spectrum disorder in 65.6% of cases.

While limited, current evidence suggests a possible association between late-onset SSRD and the subsequent development of neurodegenerative disorders, notably Lewy body spectrum disorders.