A concerning new study identified in dolphins stranded brain signs similar to human Alzheimer’s.
These are linked to cyanobacteria blooms and environmental neurotoxins in the Indian River Lagoon, Florida, which are worsened by pollution and global warming.
The research analyzed 20 bottlenose dolphins found in this area affected by intense aquatic pollution.
Dolphins with Alzheimer’s signs show brain damage
The international study, published in Communications Biology (Nature), revealed genetic and biological lesions in the brains of these marine mammals similar to those of Alzheimer’s.
The animals showed damage in neuronal metabolism and accumulation of neurotoxins produced by cyanobacteria.
Alterations in more than 500 genes linked to brain synapses and risk factors for this neurodegenerative disease were detected.
Cyanobacteria blooms release compounds like 2,4-diaminobutyric (2,4-DAB), which accumulates in marine organisms and causes structural brain damage.
The strandings coincided temporally with the peaks of toxic blooms in the lagoon, as confirmed by the study.
In particular, these concentrated in the months of higher temperature, when the concentration of toxins and environmental stress increase.
Thus, scientists established a correlation between neurotoxins and symptoms of disorientation, seizures, and behavioral changes in dolphins.
These symptoms resemble those observed in human patients with Alzheimer’s, who also experience disorientation and loss of spatial orientation.
A study in PLOS ONE (2019) had already demonstrated that the frequency of strandings and neurological problems in dolphins increases during events of toxic blooms.
The multiple effects of pollution on the nervous system of dolphins
The effects of 2,4-DAB on neurons manifested more deeply when peaks of pollution coincided with heat waves.
The damages include neuronal overexcitation and a decrease in the enzyme glutamate decarboxylase (GAD), necessary to produce the neurotransmitter GABA.
The drop in this enzyme increased vulnerability to neurological disorders and neurodegeneration associated with Alzheimer’s.
According to the European Journal of Neuroscience, sustained exposure to environmental neurotoxins generates synaptic dysfunction linked to neurodegenerative pathologies.
Additionally, at least half of the stranded dolphins showed severe hearing loss, according to previous studies.
The research thus identified altered expressions of hearing genes, such as MYO1F, STRC, and SYNE4, in the analyzed brains.
Thus, the combination of neurotoxicity and sensory alterations affected the animals’ orientation ability and weakened their social bonds.
Threat to dolphins, humans, and ecosystems
The scenario of pollution and global warming intensifies cyanobacteria blooms, according to scientists from various institutions.
This phenomenon threatens dolphins and exposes the entire local food web, including humans who consume fish or breathe contaminated aerosols.
Researchers emphasize the urgency of distinguishing between correlation and causation to clarify the cellular mechanisms involved.
Marine mammals act as ecological sentinels of deterioration in coastal ecosystems, warning of future environmental crises.
What could happen in the future with dolphins with Alzheimer’s
The authors argue that this crisis in bottlenose dolphins, due to their longevity and position in the food chain, serves as a warning for authorities responsible for environmental management.
Therefore, future research should analyze prolonged exposure to cyanobacteria blooms and their incidence on the neurological health of marine fauna.
The goal will be to determine the genetic factors involved and the impacts on auditory and cognitive systems of these species.
