The reality of dementia in lockdown

My lovely dad, Dave

My dad has alzheimer's and has been in a care home since March last year. When the coronavirus lockdown came we could only speak to him by phone and I noticed a massive decline in his speech. He babbled and made no sense. When it eased again we could visit him in the gardens and his face would light up when he saw us We'd start talking about the past and he'd be like my old dad again. Now I can only see him through a glass door which we can't hear each other through. It's so sad and frustrating