“That’s the idea that she doesn’t have dementia but the conservatorship team have suggested that she has because they want to push the conservatorship through. And if that’s the case, then that’s terrifying.”
Jamie declined to comment on the allegations made in the documentary.
However, the dad-of-three has previously declared he is working to look after his pop star daughter’s best interests and is dedicated to “protecting her”.
In 2007, Britney had a breakdown after splitting from her ex-husband, Kevin Federline.
The star went on to lose custody of her sons Jayden, 14, and Sean, 15, and was detained for 14 days for her own safety.
Britney was then placed under the conservatorship, which prevents her from driving, going out alone or making her own financial decisions.
The Battle for Britney: Fans, Cash and a Conservatorship is on BBC iPlayer now and will be on BBC Two tonight at 9pm.