The history of psychiatric illnesses correlates inversely with the age of onset of Alzheimer’s disease

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Patients with a history of depression or anxiety were significantly younger by the age of the onset of Alzheimer’s disease (AD). This is based on study results presented at the American Academy of Neurology’s annual virtual meeting from April 17-22, 2021.

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Although depression has been identified as a risk factor for accelerating the development of AD, there is limited research into the effects of psychiatric conditions such as mood and psychotic disorders, and post-traumatic stress disorder (PTSD).

The study researchers examined 1,500 patients with AD who were patients at the University of California’s Memory and Aging Center in San Francisco for a history of psychiatric disorders of depression, anxiety, bipolar disorder, schizophrenia, and PTSD.

They determined the prevalence of the disease and the relationship with age at the beginning, demographics, typical risk factors for Alzheimer’s disease (hypertension, hyperlipidemia, diabetes mellitus, education and apolipoprotein E4) [ApoE4] Gene) and novel AD-related factors (not right-handed or with a learning disability, an autoimmune disorder, or a history of seizures).

They found that 43.3% of patients had a history of depression, 32.3% had a history of anxiety, 1.2% had a history of bipolar disorder, 1% had a history of PTSD, and 0.4% have had a history of schizophrenia.

Patients with depression or anxiety were 2.1 and 3.0 years younger (P <0.001), respectively, at the age of the onset of Alzheimer's disease. The differences in the age of onset of AD doubled with each additional psychiatric diagnosis.

Patients with only 1 psychiatric disorder tended to be 1.5 years younger at onset, while patients with 2 psychiatric illnesses were 3.3 years younger and patients with 3 or more diagnoses had a 7.3 years reduction in the age of onset (P < 0.001).

Patients with depression and anxiety were more likely to be women and had fewer typical AD risk factors. The cohort of participants with depression had significantly higher numbers of autoimmune diseases (P = 0.01), while the cohort of participants with anxiety had more frequent seizures (P = 0.002).

The age differences that came with additional psychiatric diagnoses suggested that each had “unique and additive effects” on AD, according to the study’s researchers.

They concluded that the presence of depression “may reflect greater exposure to neuroinflammation and anxiety and higher levels of overexcitability when associated with autoimmune diseases and seizures”.


Eijansantos E., Allen I., Deleon J., et al. The history of a psychiatric illness correlates inversely with the age of onset of Alzheimer’s disease. Presented at: American Academy of Neurology’s Annual Virtual Meeting 2021; 17.-22. April 2021. Abstract S19.003

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