Brain Disease Can Be Devastating

Disease of the brain can cripple us, make us behave badly, or even destroy our personality and sense of self.

Major nervous system diseases:

Alzheimer's disease - causes death of nerve cells, first in the outer parts of brain (cerebral cortex) that gives us our personality and our ability to think
Depression - severe state of feeling bad that is continuous most of the day, every day
Stroke - interruption of blood supply to brain, due either to hemorrhage or to blocked arteries
Epilepsy - random episodes of convulsions
Trauma - concussion, ruptures of nerve tracts due to mechanical forces (such as sports injuries, car crashes, etc.)
Schizophrenia - complex, abnormal behaviors and thought disorders
Parkinson's disease - continuous trembling that progresses to poor ability to move

Number of cases (in millions) of certain brain diseases in any year. The number of cases of Alzheimer's disease, a disease of old age, can be expected to increase greatly, because the number of older people in the total population is increasing rapidly. The same increase will also occur with stroke and Parkinson's disease, which also increase with age. The numbers for depression is misleading, because most people recover from depression and new ones become depressed. The numbers for trauma include spinal cord trauma, which amounts to about 1/4 of the total trauma cases.

Source: National Institute of Health and Society for Neuroscience

Mental and behavioral disorders are found in people

of all regions,
all countries
all societies
in women and men at all stages of life
among the rich and poor
among people living in urban and rural areas

Recent analyses done by World Health Organization show that about 10% of people in the world suffer from a neuropsychiatric condition. This calculates to be about 450 million people! These neuropsychiatric conditions included unipolar depressive disorders, bipolar affective disorder, schizophrenia, epilepsy, alcohol and selected drug use disorders, Alzheimer's and other dementias, post-traumatic stress, obsessive-compulsive disorder, panic disorder, and primary insomnia

What Diseases Do to the Brain

they can change the anatomy (kill cells, fiber tracts)
they can change chemical messengers (transmitters) in the brain

Either kind of change can alter behavior. Example: in people who are too aggressive and violent, the brain often has lower-than-normal levels of serotonin (a transmitter). This also occurs in depression (which may be violence turned inward).

Issue: Bad brains affect behavior. But behavior (and thoughts that control behavior) affect the brain. Can we blame our bad brains for our bad behavior and thoughts? Or is that just an excuse for our failure to make better behavior choices?

How We Know