Abstract Seventy-two patients with Alzheimer's disease (AD) with late onset and vascular brain disease, dementia with hallucinatory-paranoid symptoms (the main group) were examined. The control group included 61 patients with AD with late onset and vascular disease of the brain without hallucinatory-paranoid symptoms. The risk factors for the development of hallucinatory-paranoid disorders in patients with mixed dementia were determined. These factors included: female gender; age of 78.6 ± 7.3 years old; hereditary burden of personality disorders; genetic predisposition for cognitive disorders; the presence of a neuropathic constitution in childhood; a retardation of a psychophysical development in childhood; low levels of academic performance; absence of family; secondary and secondary speciaized education; a physical type of a job; acute psychogenic factors associated with the worsening of financial conditions, conflicts in the family, and divorce.