NEW DELHI– Mood disorders such as depression, bipolar disorder, or mania that first appear after the age of 40 may not just be standalone mental health conditions—they could be early indicators of neurodegenerative diseases like dementia, according to a new study published Monday.
Researchers from Japan’s National Institutes for Quantum Science and Technology (QST) found growing evidence that late-life mood disorders (LLMDs) may precede the onset of cognitive or motor symptoms associated with diseases like Alzheimer’s, potentially offering a critical early warning sign.
The study, published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, involved brain imaging of 52 participants diagnosed with LLMDs and 47 healthy control subjects. Using positron emission tomography (PET) scans and two different tracers, researchers evaluated levels of abnormal tau protein and amyloid beta—biomarkers closely linked with neurodegenerative disorders.
They found that roughly 50% of individuals with late-onset mood disorders showed signs of tau accumulation in the brain, compared to only 15% of the control group. Likewise, amyloid deposits were detected in nearly 29% of those with LLMDs, versus just 2% in healthy participants.
The team also analyzed brain tissue from 208 autopsy cases, which further supported their findings. Individuals who had experienced late-life depression or mania showed a significantly higher prevalence of tau-related abnormalities. In many of these cases, mood symptoms emerged years—on average 7.3 years—before traditional signs of dementia such as memory loss or motor impairment appeared.
“These results support the growing view that neurodegenerative diseases, including Alzheimer’s and other tau-related disorders, can initially manifest through psychiatric symptoms,” said Dr. Shin Kurose of QST.
The research also highlighted that abnormal tau protein accumulation was often found in the brain’s frontal regions, which are vital for emotional regulation and cognitive processing—further linking mood changes with early neurodegenerative activity.
The study underscores the importance of recognizing late-onset mood disorders not just as isolated psychiatric conditions, but as possible early manifestations of underlying neurological decline. Early diagnosis could open the door to more timely interventions and disease-modifying therapies, potentially improving long-term outcomes for patients at risk of dementia. (Source: IANS)
