Gift for 90 year old

Does he like a tipple? We got my grandad a bottle of whiskey as he liked a nightcap

he is likely to be on medication with that condition, so alcohol may not be advisable.
how is he with technology.
how about some talking books, or the modern equivalent, perhaps biographies of people that interest him.
eg a hobby, fishing, history, explorers, musicians, politicians, artists, self-made entrepreneur.
as he has PD he may find it hard to hold a book steady, but might enjoy hearing something read.

A throw. Electric or otherwise.
A picture/print.
A photograph put in a frame.
A tea for two voucher.

When a relative was 90 recently we bought a beautiful, bound copy of every Times newspaper, front page, published on her birthdays. It was much appreciated and still brought out to discuss and just peruse.

It would have been my dads 90th today.I would probably have done a photo book with one of the on line companies with photos & family memories from all the decades throughout his life and made him a playlist of all his favourite music. I suppose it depends how close you are. Audio books as already mentioned is a good idea or what about a little hamper of luxury goodies that he enjoys, he may still be allowed a small tipple even if he is on medication. Maybe he has a favourite charity you could donate to in lieu of a gift.

An electric throw would be my choice for him , that's a lovely gift for anyone ! Winter will be upon us soon 🥶. Will probably treat myself to one this year!

Is there an outing he would enjoy? Even if it's only a trip to a cafe, it could be something perhaps you or someone else could do with him.

How about a donation to his favourite charity?

Marks and Spencer food hamper - or somewhere more upmarket if you want to spend more.

A photo book (as suggested above) does seem like a good idea - though maybe less so if pages are difficult.

Are you really expected to take a present?
It depends on his circumstances and your relationship.
A box of chocolates or nice jam.
I bought my DFiL a box of real cotton handkerchiefs when he was in his 90s.
A hand-knitted scarf and gloves.
I gave DMiL hand-knitted colourful fingerless gloves which she liked so much, I never saw her without them

Is his eating affected? If not, quality shortbread in a tin is a nice small gift.

We gave an aunt with this condition a particularly fragrant rose in a pot as she loved the garden but was rather unstable - it was brought onto the patio for her when in bloom.

What did he like? Did he have hobbies?

-Kits for growing indoor flowers or vegetables (for example, to grow some cherry tomatoes on the balcony)
-Kits for knitting, if your eyesight allows you to knit
-A set of delicious and high-quality tea
-Good tea service
-A heater for the winter and a blanket
-Technology (projector or audiobook)
-Night light or lamp
-A comfortable chair
Sweets are a win-win option. Just combine it with creativity, for example, print some wishes, pleasant words, a photo or a picture on the cake that can evoke pleasant emotions in the birthday person. I often do this as an addition to the main gift, adding candles/flowers. If I'm out of ideas, I look for festive universal pictures here birthdayimg.com/50th-years-free-happy-birthday-images/. Everyone loves surprise cakes.

Use search engines: Enter your topic of interest followed by "forum" in search engines like Google, Bing, or Yahoo. For example, if you're interested in gardening, search for "gardening forum." This will generate a list of relevant forums.