Omega-3 can lead to accelerated cognitive decline

Omega-3 supplements are widely used in the elderly to prevent cardiovascular diseases and dementia. However, scientific evidence on their effectiveness remains contradictory: while animal studies have shown a protective effect, controlled human trials have often failed to confirm the cognitive benefits. A new observational study based on data from the Alzheimer’s Disease Neurodegeneration Imaging Initiative (ADNI) has revealed a paradoxical pattern.

The researchers compared 273 people who took omega-3 with a control group of 546 participants who did not use these supplements. The groups were identical in terms of age, gender, and genetic factors. Over a period of five years, the participants were evaluated using three main scales:

• MMSE (Mini-Mental State Examination) is a test used to assess cognitive impairment;
• ADAS-Cog13 is a scale used to assess the severity of cognitive symptoms in Alzheimer’s disease;
• CDR-SB is a clinical dementia rating that assesses everyday functioning.

The results showed that the group taking omega-3 had a faster decline in all three tests. The decline was not affected by the presence of the APOE ε4 gene, which is traditionally considered the main genetic risk factor for Alzheimer’s disease. To investigate the reasons for the accelerated decline, the researchers examined brain scans. It turned out that the changes were not associated with the classic signs of dementia — amyloid plaques (accumulations of the amyloid protein between neurons) or tau proteins (proteins that form tangles inside cells).

Instead, the CT scan revealed hypometabolism of glucose in the brain tissue. The condition is characterized by a decrease in the ability of nerve cells to absorb and process glucose — the main source of energy for the brain. Decreased energy metabolism leads to synaptic dysfunction, i.e. impaired communication between cells (synapses). As a result, despite the absence of physical damage to the brain structure, the transmission of signals between neurons becomes less effective.

The authors of the study emphasize that their work is observational in nature and reveals a correlation (statistical relationship) rather than a direct cause-and-effect relationship. However, the findings suggest that the widespread practice of prescribing omega-3 supplements for cognitive health may need to be reconsidered. It is possible that these supplements may have an adverse impact on the functioning of synapses in certain populations of older individuals, and further research is needed to validate this hypothesis.