When a survey commissioned by the NFL recently indicated that dementia or similar memory-related diseases had been diagnosed in its retired players vastly more often than in the national population, the league claimed the study was unreliable. But confidential data from the NFL's dementia assistance plan strongly corroborates claims of a link between football and later-life cognitive impairment. Records indicate that pro football's retirees are experiencing moderate to advanced early-onset dementia at rates several times higher than the general population, the most glaring evidence to date of the dangers of professional football in past eras. As the House Judiciary Committee prepares to conduct a hearing on Wednesday on the issue of brain injuries in football, this latest data further underscores the possible safety risks of the modern game at all levels, from the NFL to youth leagues. The new information was collected by a lawyer for the 88 Plan, which the league and its players union began in 2007 to reimburse medical expenses of retirees being treated for dementia, and was presented to the union in a memorandum, which was obtained by The New York Times. The lawyer, Douglas W. Ell of the Groom Law Group, compared the age distribution of 88 Plan members with several published studies regarding dementia rates around the world, and wrote that 'the numbers seem to refute any claim that playing NFL football substantially increases' later risk for dementia. But the outside data on which he primarily based this conclusion was not only mishandled -- the wrong numbers were taken from one published study, grossly overstating worldwide dementia rates -- but the analysis also included several faulty assumptions, experts said in later interviews. Correcting for these errors indicated rates of dementia among NFL retirees about four to five times the expected rate. 'This was a preliminary effort at the request of the union to understand the facts,' said Ell, adding that he was acting as a lawyer for the union. 'I understand now that it was flawed. I believe the union wants the true facts to come out and welcomes inquiries into this area.' Joe Browne, an NFL spokesman, said in an e-mail message that because no one at the league office had yet seen Ell's analysis, it was phantom. 'I say phantom because we have not seen this analysis in our office and, if it was done, it obviously was written for the NFL player union's own self-promotional and lobbying purposes in anticipation of next week's congressional hearing,' Browne wrote. 'The executive director has made it clear that player safety is too important to be about business as usual, the NFL's special interests or our special interests,' George Atallah, a union spokesman, said, referring to the new union chief, DeMaurice Smith. 'This issue is and will always be only about the players, and we have to obtain the right information to get the right answers. The executive director has directed that all information on player health and safety be exchanged with the NFL, with the hope that they will do the same.' As brain injuries in football have come under scrutiny in recent years, and as several independent academic studies have found high rates of cognitive decline among NFL retirees, the league and its committee on concussions have consistently denied the existence of credible evidence supporting any link. When a telephone survey conducted by the University of Michigan on behalf of the NFL recently reported that its retirees aged 50 and above reported diagnoses of cognitive disease at five times the rate of the national population, the league said such surveys were unreliable. Members of the 88 Plan, however, are dementia cases that the league itself has confirmed as diagnosed by a physician and incurring expenses worthy of reimbursement. As such they represent a minimum of existing cases -- even Commissioner Roger Goodell has acknowledged that there are more candidates either unreachable or unwilling to apply -- as well as a severity of disease that is undoubtedly higher than cases in common literature, experts said. 'You know NFL players,' Goodell said when asked about the 88 Plan at his annual news conference before last season's Super Bowl. 'They've got a lot of pride. When they have a lot of pride, they don't always want to become public with their needs.' According to Ell's memorandum, 68 men ages 60 to 89 were receiving plan aid as of Oct. 1. (About 35 others had been admitted and died.) Ell then assessed how many plan members would be expected if NFL retirees in various age groups experienced dementia at rates published in six academic studies. The analysis there was faulty, however. Only four of the six studies included any data on men in their 60s, whose dementia would be defined as early-onset. One yielded an expectation of 58 dementia cases among the NFL population, another about 40. One included crude estimates from Scotland, which, after Ell further applied them improperly to the NFL population -- he didn't stratify them by age -- yielded an estimate of more than 200. The fourth included two obvious errors: The wrong column of published data was used, and those numbers were not rates per 100 but rates per 1,000. Ell's resulting estimate, 135, which he interpreted along with the Scotland figure as balancing the lower figures, should have been 73. The 88 Plan's living membership (68) looks similar to the three expectations of 58, 40 and 73. But experts in dementia epidemiology and health policy said in interviews that the 68 was far more alarming than at first glance. 'These are apples and oranges,' said Amy Borenstein, professor of epidemiology at the University of South Florida, who specializes in dementia research. 'You can't directly compare that plan's numbers to any population-based study.' First, as Goodell asserted, the program cannot include veterans who are unreachable or unwilling to apply. One unwilling player appears to be Rayfield Wright, 64, a Hall of Fame tackle for the Cowboys from 1967 to 1979 who lives in the Dallas area. His friend and caregiver, Jeannette DeVader, said that Wright had all the signs of early-onset dementia -- including short-term memory loss, frequently getting lost -- but that he would not see a neurologist, let alone apply to the 88 Plan. Wright confirmed that he did not want what he called the stigma: 'Players don't want to look at themselves that way. The truth is, you really don't want to know.' The wife of one player experiencing early-onset dementia, who asked not to be identified, said she would not apply for the 88 Plan while her husband was coherent enough to understand it. 'He would be devastated,' she said. 'They were so proud as players. They're not going to admit any weakness now, and I'm not going to break his heart by doing it for him.' Borenstein said that it was reasonable to conclude that if 68 men ages 60 to 89 are receiving aid from the 88 Plan, at least 40 or 50 more cases of similar severity are unaware of the program, unwilling to apply or do not need financial aid. This estimate was echoed by other experts in dementia and epidemiology, including Dr. Daniel P. Perl of the Mount Sinai School of Medicine in New York and Dr. Robert C. Cantu, co-director of the Center for the Study of Traumatic Encephalopathy at Boston University. In addition, according to those doctors and published studies, about half of people with dementia are considered mild cases, many of whom were unaware they had the condition before and after a study was performed. 'It's hard to believe that more than a few 88 Plan members are in what we call the mild category,' Perl said, given the anecdotal evidence and financial data the NFL released this month. The league said $6 million has been distributed to 106 members in the two-plus years the 88 Plan has been in place; given that they have received aid for various periods, that leads to more than half of members receiving $40,000 to $88,000 maximum per year in aid -- suggesting full-time at-home or institutional care, Borenstein and Perl said. And some of the cases receiving low levels of aid are advanced: Sharon Hawkins will place her 71-year-old husband, the former Oakland Raiders lineman Wayne Hawkins, in a full-time facility next week after receiving less than $10,000 per year from the 88 Plan since 2007. 'He gets lost walking the dog,' Sharon Hawkins said. 'Thank God the dog has known the way home.' Borenstein, Perl and Cantu said that if academic studies predicted about 60 NFL veterans to have dementia across the full severity spectrum, which is the case here, only about 20 to 30 would be experiencing the severity that appears in the 88 Plan. Combining the two major differences between the NFL data and estimates for the general population -- only about 25 men should have dementia to that degree, the researchers reasoned, and there are probably about 110 who do -- leaves former NFL players experiencing dementia at rates four to five times more often than normal. 'We're talking about a four-, four-and-a-half-fold increase -- that's substantial,' Perl said. 'Playing football for as long as these men have, there's no other environmental risk factor of that magnitude. There are some assumptions here, yes. The comparability of general population rates are not exact. But those assumptions are reasonable. Maybe it's three times. Maybe it's five. But these data suggest that something very serious is going on here.' In his e-mail message, Browne of the NFL wrote: 'According to the literature, dementia has many different causes, e.g., a stroke, as the result of substance abuse or family history. It also can be caused by a series of blows to the head or a severe head trauma years after a player has ended his career.' Browne's list notably did not include NFL play. His skepticism was shared earlier this year by Dan Rooney, the owner of the Pittsburgh Steelers. 'I believe that our statistics are very similar to what they are in the general population,' Rooney said after Goodell's news conference. 'I don't think that it's something that pro football players, every one of them has this. Surely there's something about getting hit. But they don't get hit as much as maybe some people are trying to say.' 