Interesting article but I am also sceptical of the idea that people are more predisposed to believe in the supernatural as they age.
I agree with Great Teacher that it's more likely that the results of the study were skewed that way due to the effects of the particular cultural 'spirit of the time' and style of education the current older generation experienced.
My experience is mirrored by many -
As a child (non JW) I truly believed in Father Christmas, fairies unquestioningly lived in the pear tree in our garden, Jesus was born in a stable and wanted me to be good, the tooth fairy left money under my pillow in exchange for a tooth, my dolls and teddies came alive whilst I was asleep, and it was real magic when Marvo the Magician pulled a rabbit out of a hat.
In my teens I believed in God in a woolly sort of way, without examining the evidence but as a result of indoctrination from Sunday school.
In my late teens I became "spiritual but not religious". Believed in the existence of ghosts and thought crop circles were probably signs of alien visitations.
In my early twenties I avidly read all the new age stuff, astrology, crystal healing, psychic ability, dousing, meditation, near death experiences, telepathy, Feng shui, bio-rhythms etc.
Mid twenties started reading about science. debunked all of the above and if asked, described myself as a Humanist.
Now in my fifties, am more certain than ever, never once found any evidence for anything supernatural.
However, during my childhood my kindly elderly grandmother, born 1888, who had finished her education at age 14, had many superstitions such as if she accidentally put her cardigan on inside out, it had to stay that way all day as otherwise she would have bad luck, and although not a church goer, she did not question that the bible must be true. No amount of reasoning could convince her that man could have landed on the moon.
The study would need to examine how many older respondents if any had changed their position from sceptic to believer during their later years.