The concept of mild cognitive impairment (MCI) primarily emphasizes changes in individuals' mental abilities, but it has recently been suggested that neuropsychiatric symptoms should also be considered important factors in age-related neurodegeneration. Psychological distress, defined as a reaction of an individual to external and internal stresses, is characterized by a mixture of psychological symptoms. It also may be considered a neuropsychiatric symptom encompassing depression, anxiety, and apathy. This paper reviews and summarizes recent evidence and relevant issues regarding the presence of psychological distress in healthy older adults and MCI patients and its relationship to risk for developing dementia. Results presented in this review show that psychological distress and depressive, anxious, and apathetic symptoms can be present in MCI and may predict progression to dementia. This article also provides suggestions for future research.