Late-Life Mood Disorders Could Be Associated With Alzheimer Disease, Dementias
PET and autopsy assays suggest that Alzheimer disease (AD) and non-AD tau pathologies could be the underlying cause of some late-life mood disorders.
Mood disorders that are diagnosed later in life, such as depression and bipolar disorder, could be warning signs of neurodegenerative diseases like depression, even before memory loss or cognitive symptoms appear. In a study published in Alzheimer’s and Dementia, investigators find that PET and autopsy assays suggest that Alzheimer disease (AD) and non-AD tau pathologies could be the underlying cause of some late-life mood disorders.1,2
PET and autopsy assays suggest that Alzheimer disease (AD) and non-AD tau pathologies could be the underlying cause of some late-life mood disorders. | Image Credit: BillionPhotos.com - stock.adobe.com
“Overall, our findings strongly suggest that tau-PET scans can detect diverse tau pathologies that underlie dementia in patients with LLMDs,” Keisuke Takahata, MD, PhD, from the National Institutes for Quantum Science and Technology, Japan, said in a news release.1
According to the study authors, late-onset depression has a higher risk of converting to bipolar depression. Further, PET studies have shown that elevated amyloid beta and tau pathologies have been associated with late-life depression. The investigators aimed to examine AD and non-Ad tau pathologies for patients who experience depression or mania without cognitive impairments after 40 years of age. Additionally, they wanted to determine the frequency and types of AD and non-AD tau pathologies in living brains when compared with healthy matched patients. To validate their findings, tissue samples from 208 autopsy cases were used.1,2
There were 52 patients with late-life mental disorders who underwent tau PET and 51 who underwent amyloid beta PET. Among the 52 patients, 23 were in remission, 28 were depressed, and 1 was manic at the time of the PET scan. Investigators found that 30 patients had a Mini-Mental State Examination score of 28 or more, 13 had a score between 24 and 27, and 8 had a score of 23 or less. One patient could not undergo the exam due to severe depression.2
Investigators found that 50% of individuals with late-life mental disorders had tau accumulation in their brains compared to 15% of the control group. Approximately 40.5% of patients with bipolar disorder and 60% of patients with depression had tau accumulation. For amyloid beta, investigators found 28.8% of participants and 2% of individuals, respectively. Patients with bipolar disorder and patients with depression had amyloid beta accumulation at 22% and 36%, respectively. For both proteins, individuals with current episodes of depression or mania were similar to those without at 51.7% and 31%, respectively, compared with 47.8% and 26.1%, respectively. The autopsy findings further supported these data.1,2
In addition to these findings, they also observed that individuals had tau accumulation in the frontal regions of the brain, which is related to emotional regulation and cognitive function. Because of these findings, investigators believe that this could be detected before traditional cognitive symptoms of dementia, with the autopsy cases showing mood disorders preceding cognitive or motor symptoms by an average of 7.3 years.1
“Because most of the participants with LLMDs [late-life mood disorders] in our study had no or mild cognitive decline, these results support the evidence that neurodegenerative diseases, including Alzheimer and non-Alzheimer tau-related pathologies, can initially manifest as psychiatric symptoms,” Shin Kurose from the National Institutes for Quantum Science and Technology said in the news release.1
READ MORE: Neurology Resource Center
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