Performance on complex memory tests is associated with β-amyloid in individuals at risk of developing Alzheimer's disease.

The pathophysiological development of Alzheimer's disease (AD) begins in the brain years before the onset of clinical symptoms. The accumulation of beta-amyloid (Aβ) is thought to be the first cortical pathology to occur. Carrying one apolipoprotein E (APOE) ε4 allele increases the risk of developing AD at least 2-3 times and is associated with earlier Aβ accumulation.

Subjective cognitive complaints in patients with Parkinson's disease.

Mild cognitive impairment (MCI) is common in Parkinson's disease (PD), affecting almost all patients with PD at some time. It has been shown that patients with PD, who express subjective cognitive complaints, are at a higher risk of eventually developing PD-MCI. This is corroborated by the Movement Disorders Society's (MDS) diagnostic criteria from 2012 for PD-MCI, from which it follows that a subjective cognitive complaint must be present in addition to objective cognitive impairment for a patient with PD to receive a diagnosis of PD-MCI.