Separating a potentially effective drug from background noise is a challenge in any medical field, but perhaps particularly in the much-publicised longevity industry. In one of its most recent ventures, researchers have claimed that a supplement given to ageing dogs can reverse some of their cognitive decline. But before dog owners start wagging their tails with delight, some researchers are concerned they could be barking up the wrong tree.
and her colleagues at North Carolina State University recruited 67 dogs of 36 breeds, all aged 10 years or older. The dogs were given a placebo or a low- or high-dose treatment, with their owners being unaware what they received.
On two consecutive days once a month for six months, the dogs in the treatment groups took a supplement containing a senolytic 鈥� a type of drug that targets senescent cells. These cells don鈥檛 die off when they stop dividing and can release inflammatory chemicals linked to ageing and ill health. They also took a compound every day that supposedly increases levels of the molecule NAD+, which is involved in many key biological processes and declines with age.
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All the dogs, including those taking the placebo, showed signs of improvement on a canine cognitive dysfunction rating 鈥� which measures behaviours such as staring into space, acting aggressively and pacing 鈥� compared with before the experiment, with this being particularly pronounced in the high-dose treatment group.
Writing in their paper, the authors say that the animals receiving a higher dose also showed signs of reduced frailty, as well as improved activity levels and happiness, all of which were reported by their owners.
, which funded the study, lauded it as 鈥渢he first clinical evidence that it is possible to reverse age-related decline in dogs鈥�. at Harvard Medical School, who founded the firm, promptly .
The researchers declined to discuss the results with New 杏吧原创 ahead of the paper being peer reviewed, but scientists not involved in the study say it may not be such a cause for celebration.
at the University of Liverpool in the UK says that of all the results, only the improvement in cognition between the dogs receiving a high treatment dose versus those on the low dose or a placebo was statistically significant, which suggests that it didn鈥檛 occur due to chance. 鈥淎lthough trends can of course be mentioned, most of these results were nowhere near significant and should not be overstated,鈥� she says.
The fact the placebo dogs improved cognitively compared with their scores at the start of the study suggests another factor may be at play, says Wallis, perhaps the increased attention and stimulation they received through interacting with their owners as part of the research. We don鈥檛 know if the treatment caused any physiological changes because the authors didn鈥檛 measure any modifications to the animals鈥� NAD+ levels or senescent cells.
The cognition improvement was also based on scoring by owners, rather than vets, reducing the confidence we can place on it, she says.
In addition, due to deaths and health-related withdrawals among the dogs, just 62 and 56 animals completed three and six months of the trial, respectively. When it came to those in the high-dose treatment group specifically, only 18 dogs took the therapy for at least three months, when some initial results were reported.
鈥淭hey also didn鈥檛 attempt to account for differences in breed, and no information is provided on whether dogs were intact or neutered,鈥� says Wallis. Research suggests .
at the University of Michigan was more damning still, describing the paper as 鈥�95 per cent hype鈥�. While the authors write that none of the adverse outcomes recorded during the study 鈥� which included anaemia and blood in the urine 鈥� was linked to the treatment, Miller says we don鈥檛 know if it is safe long term.
鈥淭he company trying to make money with this publicity campaign seems to be trying to create an impression of benefit based on exceptionally weak evidence,鈥� he says. 鈥淭here is also no evidence that the drug combination, given over months or years, will not create medical problems in treated dogs. A lot of dog lovers will be fooled.鈥�
bioRxiv
