New research from the USA identifies an association between the consumption of cured meat products and mania. The evidence comes from both human medical cases and from studies of rats.
Mania is a component of bipolar disorder and is managed by medication such as lithium. It is a recurrent problem often associated with poor decision-making.
Liability for first party loss caused by legally defective cured meat products could extend to the financial decisions made during an episode of mania. Third parties might include the victims of road traffic accidents.
What did the research show?
Compared with controls, a history of eating cured meat preparations was significantly associated with being in the mania group (mean age 34, 66% female); adjusted odds ratio = 3.49 (2.24–5.45). There was no significant association with undercooked meat, raw meat, undercooked fish or raw fish.
A history of eating cured meat preparations was not associated with a diagnosis of schizophrenia or schizoaffective disorder, BPD, bipolar depression, or major depressive disorder.
In a subgroup of mania cases it was found that cured meats prepared by dehydration were not associated with mania.
Recall bias could be an explanation for the association but the diet survey included a number of items that a person might regard as risky and these were not associated with mania. The same association with cured meat was not found in other diagnoses which might have similar biases and delusion risk. The association has a good chance of being genuine unless the control group was biased in some unrecorded way.
So what is the difference between cured meat and dry cured meat?
Narrowing down the options
The researchers tested rats fed with normal food, a mixture of normal food and beef jerky and a mixture of normal food beef and nitrates. It turns out that hyperactive behaviour was only seen in foods containing added nitrates.
The causal relationships that could explain this association include reverse causation (where a person on the verge of mania chooses to eat beef jerky), exacerbation of an underlying condition and, outright causation. More research is needed to resolve these issues. But one of the main problems to work on is that nitrates are common place in normal foods, sometimes at far higher levels than found in beef jerky, spinach for example has ten times as much nitrate per serving. What is different about added nitrates in cured meat products? Does the difference leave any specific signs? Etc.
For insurers the question of cumulative effects, threshold effects and reversibility would help decide who should pay, if anyone.
Size of the problem.
It may seem far too early on to start working on the numbers but sometimes a liability exposure context is useful in deciding what to do next.
Working through the published numbers generated by this preliminary study it turns out that around 25% of current mania cases could be attributed to the consumption of meat sticks and the like. For the UK that would be around 760 new diagnoses a year or perhaps 3,000 hospital episodes depending on whether the association is due to causation or exacerbation.
These would be significant new caseloads for the UK especially as disease onset is common before the age of 30. It would be worth keeping an eye on this research.