Mr Anderson was diagnosed 18 months ago but has spoken about it publicly for the first time for an Alzheimer's Society walk launch on Thursday.
The 83-year-old, who lives in Henley-on-Thames, said of living with the condition: "I've lost my freedom."
Thunderbirds was filmed on Slough Trading Estate in Berkshire and was first broadcast in 1965.
Speaking on BBC Berkshire he said: "I don't think I realised at all. It was my wife Mary who began to notice that I would do something quite daft like putting the kettle in the sink and waiting for it to boil.
"Finally I was persuaded to go and see the doctor and eventually I was confronted with the traditional test - a piece of paper with drawings on it, taking a pencil and copying them.
"I thought 'Why are they doing this? A child could do this'.
"But when I started to copy the drawings, that wasn't the case.
What is Alzheimer's Disease?
"I started to get in a muddle. That's when I began to realise that there was something wrong."
Mr Anderson, who also created the marionette puppet series Joe 90 and Captain Scarlet and the Mysterons, said being told he was no longer able to drive "was the bitterest blow of all".
"That virtually took away my freedom. It meant that I couldn't go to Pinewood studios where I worked, and this depressed me enormously because my film work was my life.
"Suddenly my life was cut off. Since I've had Alzheimer's I've realised how debilitating it is. It can affect your life in so many ways that you don't think about."
Mr Anderson was diagnosed with Alzheimer's in early 2010 but his son Jamie said the family noticed recurring symptoms "five or six years ago".
"Little things like losing his way on car journeys he's done for 20 years or more, using very strange ingredients when making soups, struggling to dial numbers," he said.
"We look with hindsight now and we see symptoms that were recurring five or six years ago and if we'd bitten the bullet and dealt with it then perhaps it would have been different."
Mr Anderson will be taking part in the Windsor Memory Walk with Jamie on 13 October in support of the Alzheimer's Society, which is encouraging people to sign up for the walks that will take place around England.
Alzheimer's Society chief executive Jeremy Hughes said: "We're so grateful to Gerry for supporting Memory Walk.
"By speaking out about his dementia he's spreading the message much further that it can happen to anyone."
The creator of Thunderbirds, Gerry Anderson, has revealed he has Alzheimer's Disease.