LATE describes a prevalent age-related medical condition which leads to impaired memory and thinking. It's extremely common in people over 85 - some recent studies putting the rate as high as 60% (ref.)

It can only be unequivocally diagnosed at autopsy, and is very often confused with Alzheimer's diseaseplugin-autotooltip__plain plugin-autotooltip_bigAlzheimer's disease

"Alzheimer’s disease is a chronic progressive neuro-degenerative disorder characterised by three primary groups of symptoms. The first group (cognitive dysfunction) includes memory loss, language difficulties, and executive dysfunction (that is, loss of higher level planning and intellectual coordination skills). The second group comprises psychiatric symptoms and behavioural disturbances — for example, depression, hallucinations, delusions, agitation — collectively termed … and other forms of Dementia.

The 'TDP-43' in the name refers to an important human protein known as 'TAR DNA-binding protein 43' . In LATE, it's known that the prevalence of a 'mis-folded' version of the protein increases in brain tissues. This problem was only discovered in the mid 1990s, and the disease was not named LATE until 2019. (ref.)

It is not currently known why the proteins mis-fold, or why they accumulate in certain brain regions such as the amygdala and hippocampus.

It's thought likely that various lifestyle, genetic and/or environmental conditions may contribute to LATE's prevalence.