T lymphocyte proportion in Alzheimer’s disease prognosis

Abstract

Bai et al investigate the predictive value of T lymphocyte proportion in Alzheimer's disease (AD) prognosis. Through a retrospective study involving 62 AD patients, they found that a decrease in T lymphocyte proportion correlated with a poorer prognosis, as indicated by higher modified Rankin scale scores. While the study highlights the potential of T lymphocyte proportion as a prognostic marker, it suggests the need for larger, multicenter studies to enhance generalizability and validity. Additionally, future research could use cognitive exams when evaluating prognosis and delve into immune mechanisms underlying AD progression. Despite limitations inherent in retrospective designs, Bai et al's work contributes to understanding the immune system's role in AD prognosis, paving the way for further exploration in this under-researched area.

Key Words: Alzheimer's disease; T lymphocyte; T lymphocyte proportion; Alzheimer's disease prognosis; Modified rankin scale; Immune cell count; Electroencephalogram; Immune function

Core Tip: Bai et al propose a novel marker for Alzheimer's disease (AD) prognosis: The proportion of T lymphocytes. In their single-center retrospective study, they found that a decrease in T lymphocyte proportion correlated with a poorer prognosis, as measured by the modified Rankin scale. This suggests T lymphocytes could serve as a predictive biomarker for AD prognosis. The study underscores the need for larger, multicenter investigations to validate these findings and highlights the potential of immune system dysregulation in AD progression, opening avenues for further research in understanding AD pathology and prognosis.

TO THE EDITOR

Bai et al[1] describes how a decrease in the proportion of T lymphocytes may predict poor prognosis in Alzheimer’s disease (AD). In this single-center retrospective study, 62 patients with a clinical diagnosis of AD were ultimately enrolled after admission to the Third Affiliated Hospital of Guizhou Medical University[1]. As an assessment of neurologic function and prognosis, the modified Rankin scale (mRS) was recorded at admission, discharge, and follow-up[1]. In addition to blood immune cell flow cytometry for immune cell count, electroencephalogram, brain magnetic resonance imaging, and routine blood tests were recorded at admission[1]. Ultimately, Bai et al[1] determined that the proportion of T lymphocytes < 55% as determined on flow cytometry was predictive of a poor prognosis as determined by an elevated mRS score of 3-6 in AD patients.

DISCUSSION

While the mRS may allow for assessment of the functional status of a patient from the perspective of their ability to perform daily activities, further evaluation of the cognitive function of the patients when determining severity staging could be concluded from other exams such as the Mini-Mental State Examination, Montreal Cognitive Assessment Basic, and the Alzheimer's Disease Assessment Scale-Cognitive subscale[2,3]. The inclusion of these exams when determining the prognosis of the patients with AD may increase the validity of the study.

While there is clear evidence that chronic inflammation in the brain, a potential byproduct of immune dysregulation, is implicated in the progression of AD, the precise role of inflammation or immune dysregulation is not clearly understood in the setting of AD. Studies of systemic immune-mediated inflammatory diseases have been inconclusive in indicating systemic inflammation or immunosuppression as a potential risk for the development of AD, but may suggest that immune dysregulation is a downstream symptom of AD progression[4,5]. Whether a downstream product of AD progression or a preceding cause, the reduction in the proportion of T lymphocytes observed by Bai et al[1] may offer some insight into the prognosis of AD patients.

Future studies investigating the connection between T lymphocytes and AD prognosis would benefit from an increased sample size to increase the power of the study and reduce the risk of Type II errors. Additionally, studies that involve patients from multiple hospitals rather than single centers could increase the generalizability of the study to a broader population and enhance external validity.

As the study design was retrospective in nature, it is susceptible to common limitations of this approach, such as the presence of confounding variables. For instance, Bai et al[1] investigated T lymphocyte proportion, which can be altered in a wide range of clinical presentations. Factors such as age, comorbidities like diabetes or cardiovascular disease, and lifestyle factors may influence the relationship between the T lymphocyte proportion and AD prognosis.

Future research may also benefit from studies that focus on exploring the immune mechanisms involved with the interplay between the immune system and AD prognosis. Research that focuses on the molecular and cellular pathways involved in immune system function and AD pathology may be valuable in deciphering the role T lymphocytes play in AD prognosis.

CONCLUSION

Bai et al’s exploration of the connection between T lymphocytes and AD disease progression addresses an area of AD research that has been largely understudied[1,6]. Though the study has certain limitations expected in a preliminary retrospective study, this research represents vital progress towards unveiling the complex role of our immune system in AD and enhancing our understanding of the positive predictive value of T lymphocyte proportion in AD prognosis.