dementia alzheimer brain disease

alzheimer dementia brain neurology neurodegenerative mental health amyotrophic lateral sclerosis als memory mind disease ill multiple system atrophy msa illness age aging transform function loss cognition alzheimers creutzfeldtjakob parkinsons forget motor neurons depression elderly neuron old people gear cog machine thinking think concept conceptual remember transfer knowledge psychology metaphor black background transforming human head gears wheels degrading