After Alzheimer's, Parkinson's disease is the second most common degenerative brain disorder.
Parkinson’s disease afflicts some 1.5 million Americans, with about 60,000 new cases — split roughly equally between men and women — appearing annually.
A neurotransmitter called dopamine is essential to control of mood and muscle/body movement, and Parkinson’s is caused by damage to the brain's dopamine-producing cells.
The cause(s) remain uncertain, but the available evidence points to a combination of genetic and environmental factors, especially pesticide exposure.
Symptoms include tremors, muscle rigidity, poor balance, cramped handwriting, stiff facial expression, shuffling walk, muffled speech, hallucinations, and depression.
Parkinson's disease usually develops after age 60, but about 15 percent of cases occur in people under 50.
Actor Michael J. Fox — who developed symptoms at age 30 — ranks among the best-known early-onset Parkinson’s patients and research advocates.
New research from Sweden shows that certain fish — like salmon, herring, and cod — abound in a protein that appears to help prevent the buildup of “junk” brain proteins linked to Parkinson’s.
But before we get to that, let's review the key role that seafood-source omega-3 fatty acids — as well as fishy diets, extra virgin olive oil, and caffeine — appear to play in maintaining the brain's ability to produce ample dopamine.
Fish versus Parkinson’s: The benefits begin with omega-3s
Fishy diets first made Parkinson’s-related headlines about a decade ago.
Back in 2007, a U.S.-Canadian team reported that diets high in seafood-source omega-3 DHA protected mice from injections of an opiate that kills dopamine-producing cells.
(Omega-3 DHA has also been shown to help blunt the impact of simulated concussions and spinal injuries in rodents and speed their recovery.)
The international team discovered that omega-3 DHA displaced omega-6 fatty acids in the animals' brain cell membranes.
This led them to suspect that brains overabundant in omega-6 fatty acids — like the average American’s — may be more vulnerable to Parkinson's and suffer a speedier decline in dopamine production. (For more on that study, see Omega-3 May Help Deter Parkinson's Disease.)
More recently, lab research showed that omega-3-deficient diets drastically cut the numbers of dopamine-producing (dopaminergic) brain cells in animals' brains, and reduced the ability of brain cells to resist the damaging oxidative effects of the pesticide paraquat on dopaminergic brain cells.
Animals given omega-3 deficient diets also suffered drastic reductions in the numbers of brain cells that produce a chemical (BDNF) known to protect brain cells, foster growth of connections among brain cells, and help deflect neurodegenerative diseases like Parkinson’s.
And other animal research showed that dietary omega-3s can promote the conversion of brain stem cells into dopamine-producing (dopaminergic) cells.
Fishy diets and caffeine also help
European diet-health studies link diets that closely resemble the rural “Mediterranean” diet to reduced rates of Parkinson’s disease (Alcalay RN et al. 2012; Cassani E et al. 2017).
Rural Mediterranean diets are typically high in green vegetables, fruits, seafood, poultry, cheese, nuts, beans, whole grains, and extra-virgin olive — but low in red meats, sugars, starchy or processed foods, and cheap, omega-6-heavy vegetable oils.
(Why would extra-virgin olive oil aid brain health? The uncommon, tyrosol-type antioxidants that abound only in extra-virgin grade olive oil help the brain's vascular health and boost brain levels of BDNF: a key brain-protector and growth-promoter.)
Similar studies from Japan support the idea that diets rich in vegetables, fruit, and fish offer protection against Parkinson's disease.
Coffee, tea, and other caffeine-carriers may also be beneficial. Epidemiological and animal studies support caffeine’s Parkinson's-preventive potential, which may be why — along with their potent antioxidants — coffee and tea consumption is linked to reduced risk for the disease.
Swedish study finds brain-cleaning protein in salmon, cod and other fish
The intriguing new findings comes from Sweden’s Chalmers University of Technology and may help explain why fishy diets promote better long-term brain health.
One of the hallmarks of Parkinson’s disease is the accumulation of alpha-synuclein — sometimes called the “Parkinson’s protein” — in the brain.
Alpha-synuclein is an “amyloidogenic” protein that promotes formation of proteins like the beta-amyloid that abounds in the brains of most Alzheimer’s patients.
However, it remains unclear whether the amyloid protein buildup seen in the brains of most Parkinson’s, Alzheimer’s, ALS, and Huntington’s disease patients is a cause of those conditions, a symptom, or a bit of both.
The Swedish team discovered that parvalbumin from wild salmon, cod, herring and other common fish helps prevent accumulation of amyloid proteins that form from alpha-synuclein.
And they found that parvalbumin tends to form amyloid proteins that bind to alpha-synuclein, thereby keeping it from turning into potentially harmful amyloid proteins.
“Parvalbumin collects up the ‘Parkinson’s protein’ and actually prevents it from aggregating, simply by aggregating itself first,” explained biochemist and study lead author Pernilla Wittung-Stafshede, Ph.D.
Although parvalbumin occurs in many fish, the richest sources include sockeye salmon, cod, herring, carp, and red snapper — with the levels of parvalbumin varying seasonally.
Parvalbumin is responsible for most fish allergies, but the parvalbumin in cartilaginous species (such as sharks and rays) is much less allergenic than the parvalbumin in bony fish.
“Levels of parvalbumin are much higher in fish after they have had a lot of sun, so it could be worthwhile increasing consumption during autumn,” said bio-engineer and study co-author Nathalie Scheers, Ph.D.
(Note: Much of the wild salmon and other wild fish on the market was frozen after harvest, and it’s hard to know when that happened. Just eat fish routinely to ensure that some of it was harvested in the late summer or fall.)
The Swedish team say they’ll dig deeper, to see if their discovery may hold implications for other neurodegenerative disorders — including Alzheimer’s.
Professor Wittung-Stafshede stressed the importance of such research: “These diseases come with age, and people are living longer and longer. There’s going to be an explosion of these diseases — and the scary part is that we currently have no cures.”
Her team will conduct a follow up study later in 2018, designed to track the transport of herring-derived parvalbumin in human tissues.
Should they find anything of promise for prevention or treatment of Parkinson’s, we’ll let you know.
For now, the combined brain-protecting potential of fish-source omega-3s and this fishy protein add more good reasons to give fish a prominent place in your menu plans.