Cognitive disorders are a group of mental health diseases that cause several effects on mental abilities, such as learning, problem-solving, memory, and perception. The most important cognitive disorders are delirium, dementia, and amnesia.

  • Delirium: an acute confusional state characterized by inactivation, disorganized thinking, and confusion of space and time.
  • Dementia: progressive brain deterioration, memory impairment, confusion, and loss of concentration.
  • Amnesia: a memory disorder characterized by loss of short-term memory that interferes with daily life.

Among cognitive disorders, chemobrain, a cognitive impairment caused by chemotherapeutic agents, is increasing attention. These chemical agents could substantially reduce the quality of life in cancer patients since they induce memory impairment, slow processing speed, and inability to concentrate. These cognitive dysfunctions seem to be linked to reducing neuronal integrity at the hippocampus and frontal system levels.

Scientists investigated the potential effect of astaxanthin from Haematococcus Pluvialis as a protective compound able to drastically contrast the decline of cognitive functions induced by doxorubicin (DOX). Astaxanthin showed neuroprotection and memory-enhancing impact and switched off inflammation and oxidative stress, mitigating the increase of acetylcholinesterase activity and suppressing several pro-apoptotic stimuli.

Astaxanthin also produces beneficial effects in other body compartments and cells, directly affecting brain health. In particular, the positive influence of a diet rich in polar carotenoids, such as astaxanthin, on an abnormal accumulation of phospholipid hydroperoxides (PLOOH) in the erythrocytes of patients affected by dementia has been recorded.

PLOOH are the primary oxidation products of phospholipids, and their accumulation in erythrocytes induces a reduction in oxygen transport to the brain, facilitating the progression of dementia. Lower PLOOH levels in the erythrocytes and blood cells of patients were treated with astaxanthin for the control (placebo group), demonstrating that this bioactive molecule is responsible for improving erythrocyte antioxidant status, which may contribute to the prevention of dementia.

Some marine food products are recommended by many medical authorities worldwide. In particular, fish oil usually contains tocopherols, saturated fats, monounsaturated fats (mostly palmitoleic and oleic acids), and polyunsaturated fatty acids (PUFA, such as eicosapentaenoic acid, EPA, and docosahexaenoic acid, DHA). A balanced proportion between EPA and DHA (3:2, regularly found in natural fish oil) seems to be a key factor for beneficial effects, such as the slowing down of cognitive decline and reduced depression. In contrast, many other PUFAs (for instance, the pro-inflammatory arachidonic acid) could be responsible for massive ROS production with consequent activation of immune cells.

The combination of astaxanthin and fish oil enhances the positive effect on brain health by reducing harmful effects due to PUFAs. In particular, a Wistar rat fed with 1 mg/kg of astaxanthin and 1 mg/kg of fish oil presented lipid protection status at the anterior forebrain level.

Moreover, Trolox equivalent antioxidant capacity (TAEC) and Ferric Reducing Antioxidant Power (FRAP) assessed in brain homogenates were increased in rats fed with a mix of astaxanthin and fish oil. A similar investigation was carried out, which showed the beneficial effects of a mixture of xanthophyll carotenoids and fish oil (containing EPA and DHA) on the human brain. This particular functional food, probably due to its potent antioxidant potential, reduced the progression of neurodegeneration, acting on memory, sight, and mood. Reducing ROS production linked to marine functional foods, such as fish oil, represents a valid mechanism to prevent cognitive dysfunctions.