TNF and dementia: The exact biological mechanisms of the observed association between LTL and dementia should be explored: those pathways that shorten telomeres, modulate the function of immune cells in the central nervous system and induce senescence of T cells in the blood.26 The telomere length of T cells is inversely correlated with serum levels of tumour necrosis factor-α (TNF-α) (a clinical marker of disease status).