Physical changes in the brain associated with aging include:

• Atrophy (shrinkage) of tissue in some regions
• Increased ventricular volume
• Loss of neurons and synapses and reduced formation of new neurons
• Accumulation of abnormal proteins

Other significant changes include:

• Reduced glucose utilization
• Chronic inflammation
• Vascular changes
• Reduction/deterioration of myelination
• Abnormalities of astrocytes and neuron-supporting cells
• Impaired destruction and clearance of abnormal/damaged proteins
• Alterations in gene expression

Behaviors that may be observed with cognitive decline include increased anxiety and reduced coping ability (including destructive behaviors); compulsive behaviors; confusion; altered social interactions, reduced ability to navigate environments; changes in sleeping; decreased response to commands; reduced ability to predict feeding time; and changes in toileting and feeding behaviors