Combining alcohol with other drugs can make the effects of these other drugs much stronger and more dangerous. Many accidental deaths have occurred after people have used alcohol combined with other drugs. Cannabis, tranquillizers, barbiturates and other sleeping pills, or antihistamines (in cold, cough, and allergy remedies) should not be taken with alcohol. Even a small amount of alcohol with any of these drugs can seriously impair a person's ability to drive a car.

This shows a 20-year old female nondrinkers response to the spatial working memory task. Brain activation is shown in bright colors.

This shows an alcohol-dependent 20-year old female's response to the spatial working memory task. Brain activation is shown in bright colors.

People who drink on a regular basis become tolerant to many of the unpleasant effects of alcohol, and thus are able to drink more before suffering these effects. Yet even with increased consumption, many such drinkers don't appear intoxicated. Because they continue to work and socialize reasonably well, their deteriorating physical condition may go unrecognized by others until severe damage develops - or until they are hospitalized for other reasons and suddenly experience alcohol withdrawal symptoms.

Psychological dependence on alcohol may occur with regular use of even relatively moderate daily amounts. It may also occur in people who consume alcohol only under certain conditions, such as before and during social occasions. This form of dependence refers to a craving for alcohol's psychological effects, although not necessarily in amounts that produce serious intoxication. For psychologically dependent drinkers, the lack of alcohol tends to make them anxious and, in some cases, panicky.

Physical dependence occurs in consistently heavy drinkers. Since their bodies have adapted to the presence of alcohol, they suffer withdrawal symptoms if they suddenly stop drinking. Withdrawal symptoms range from jumpiness, sleeplessness, sweating, and poor appetite, to tremors (the "shakes"), convulsions. hallucinations. and sometimes death.

Alcohol abuse can take a negative toll on people's lives, fostering violence or a deterioration of personal relationships. Alcoholic behavior can interfere with school or career goals and lead to unemployment.

Long term alcohol abuse poses a variety of health risks, such as as liver damage and an increased risk for heart disease. Fetal Alcohol Syndrome may result from a pregnant woman's drinking alcohol; this condition causes facial abnormalities in the child, as well as growth retardation and brain damage, which often is manifested by intellectual difficulties or behavioral problems.

The left image is an averaged image of 10 nondrinker/social drinker young women, and the right is an averaged image of the 10 alcohol-dependent young women. Red, orange, and yellow show where the brain was active during spatial working memory, with yellow indicating the highest level of activity. Notice that there is less yellow in the back (bottom of the picture) right of the alcohol-dependent women's fMRI.

The effects of any drug depend on several factors:

• the amount taken at one time
• the user's past drug experience
• the manner in which the drug is taken
• the circumstances under which the drug is taken (the place, the user's psychological and emotional stability, the presence of other people, the concurrent use of other drugs, etc.).
  

It is the amount of alcohol in the blood that causes the effects. In the following table, the left-hand column lists the number of milligrams of alcohol in each decilitre of blood - that is, the blood alcohol concentration, or BAC. (For example, an average person may get a blood alcohol concentration of 50 mg/dL after two drinks consumed quickly.) The right-hand column describes the usual effects of these amounts on normal people - those who haven't developed a tolerance to alcohol.

Blood Alcohol Concentration
(ma/dL) Effect