Functions

sets the emotional tone of the mind

filters external events through internal states (emotional coloring)

tags events as internally important

stores highly charged emotional memories

modulates motivation

controls appetite and sleep cycles

promotes bonding

directly processes the sense of smell

modulates libido

Problems

moodiness, irritability, clinical depression

increased negative thinking

perceive events in a negative way

decreased motivation

flood of negative emotions

appetite and sleep problems

decreased or increased sexual responsiveness

social isolation

ALZHEIMER'S DISEASE

Alzheimer's Disease is a specific neurodegenerative disease and is the most common cause of dementia in old people. Clinically, it is characterized by loss of memory, inability to learn new things, loss of language function, a deranged perception of space, inability to do calculations, indifference, depression, delusions, and other manifestations. It is inexorably progressive and fatal within 5 to 10 years. AD patients usually die of complications of chronic illness. AD is the fourth to fifth most common cause of death in the United States. Sometimes AD involves people in their 40s and 50s, but is mainly a disease of old age. Its overall incidence in persons over 65 is approximately 10%. Its incidence in persons over 85 approaches 50%.

PATHOLOGY OF AD AD is characterized by two processes , beta amyloid deposition and neurofibrillary change (degeneration). Biochemically, both these processes are due to postranslational modifications of extracellular (amyloid) and intracellular (neurofibrillary change) proteins (see further on). Beta amyloid deposition is specific for AD. Neurofibrillary change is also seen in other degenerative diseases.
Beta amyloid (Aß) is a polymer of a 42 to 43 amino acid peptide derived from a larger precursor protein, the Amyloid Precursor Protein (APP). APP is a transmembrane protein, made by neurons and other brain cells. It is also found in extraneural tissues and is especially abundant in platelets. Its function is unknown. The Aß amyloid residue includes part of the transmembrane domain of APP and is thought to result from aberrant cleavage of APP by proteolytic enzymes called secretases . Defective clearance of Aß leads to its aggregation, changes its folding pattern, and causes it to precipitate as amyloid.