Pre-dementia states considered as prodromal are mild cognitive impairment (MCI), and mild behavioral impairment (MBI).

Kynurenine is a metabolite of tryptophan that regulates microbiome signalling, immune cell response, and neuronal excitation. A disruption in the kynurenine pathway may be associated with the neuropsychiatric symptoms and cognitive prognosis in mild dementia.

In this stage signs and symptoms may be subtle. Often, the early signs become apparent when looking back. 70% of those diagnosed with MCI later progress to dementia. In MCI, changes in the person's brain have been happening for a long time, but symptoms are just beginning to appear. These problems, however, are not severe enough to affect daily function. If and when they do, the diagnosis becomes dementia. They may have some memory trouble and trouble finding words, but they solve everyday problems and competently handle their life affairs. During this stage, it is ideal to ensure that advance care planning has occurred to protect the wishes of the person. Advance directives which are specific to dementia exist, which can be particularly helpful in addressing the decisions related to feeding which come with the progression of the illness.

Mild cognitive impairment has been relisted in both DSM-5, and ICD-11, as mild neurocognitive disorders – milder forms of the major neurocognitive disorder (dementia) subtypes.