Since mood swings and unpredictable behavior are frequent occurrences for preteens and teenagers, parents may find it difficult to spot signs of alcohol and drug abuse. But if your child starts to exhibit one or more of these signs (which apply equally to sons and daughters), drug abuse may be at the heart of the problem:

• She's withdrawn, depressed, tired, and careless about personal grooming.

• He's hostile and uncooperative; he frequently breaks curfews.

• Her relationships with family members have deteriorated.

• He's hanging around with a new group of friends.

• Her grades have slipped, and her school attendance is irregular.

• He's lost interest in hobbies, sports, and other favorite activities.

• Her eating or sleeping patterns have changed; she's up at night and sleeps during the day.

• He has a hard time concentrating.

• Her eyes are red-rimmed and/or her nose is runny in the absence of a cold.

• Household money has been disappearing.

The presence of pipes, rolling papers, small medicine bottles, eye drops, or butane lighters in your home signal that your child may be using drugs. Other clues include homemade pipes and bongs (pipes that use water as a filter) made from soda cans or plastic beverage containers. If any of these indicators show up, parents should start discussing what steps to take so they can present a united front. They may also want to seek other family members' impressions.

If you suspect that your child is using drugs, you should voice your suspicions openly — avoiding direct accusations — when he or she is sober or straight and you're calm.

This may mean waiting until the next day if he comes home drunk from a party, or if her room reeks of marijuana. Ask about what's been going on — in school and out — and discuss how to avoid using drugs and alcohol in the future. If you encounter reluctance to talk, enlist the aid of your child's school guidance counselor, family physician, or a local drug treatment referral and assessment center — they may get a better response. Also explore what could be going on in your child's emotional or social life that might prompt drug use.

Taking the time to discuss the problem openly without turning away is an important first step on the road to recovery. It shows that your child's well-being is crucial to you and that you still love him, although you hate what he's doing to himself. But you should also show your love by being firm and enforcing whatever discipline your family has agreed upon for violating house rules. You should go over ways to regain the family's trust such as calling in, spending evenings at home, and improving grades.

Even in the face of mounting evidence, parents often have a hard time acknowledging that their child has an alcohol, tobacco, or drug problem. Anger, resentment, guilt, and a sense of failure are all common reactions, but it is important to avoid self-blame. Drug abuse occurs in families of all economic and social backgrounds, in happy and unhappy homes alike. Most important is that the faster you act, the sooner your child can start to become well again.

No one who begins to use drugs thinks he or she will become addicted. Addiction is a disease characterized by compulsive drug-seeking behavior regardless of the consequences. Research conducted by the National Institute on Drug Abuse clearly shows that virtually all drugs that are abused have a profound effect on the brain. Prolonged use of many drugs including cocaine, heroin, marijuana and amphetamines can change the brain in fundamental and long-lasting ways, resulting in drug craving and addiction.

If and when a drug abuser becomes addicted depends on the individual. Research shows that children who use alcohol and tobacco are more likely to use marijuana than children who do not use these substances. Children who use marijuana are more likely to use other addictive drugs. Certain genetic, social, and environmental risk factors make it more likely that certain individuals will become addicted to alcohol, tobacco, and other drugs. These include:

• children of alcoholics who, according to several studies, may have inherited genes that make them more prone to addiction, and who may have had more stressful upbringings;

• sensation-seekers who may like the novelty of feeling drunk or high;

• children with psychological problems, such as conduct disorders, who self-medicate to feel better;

• children with learning disabilities, and others who find it difficult to fit in or become frustrated learning;

• children of poverty who lack access to opportunities to succeed and to resources when they're in trouble.

The more risk factors children have, the greater their vulnerability. And everyone has a different ability to tolerate drugs and alcohol — what if your child's tolerance is very low?

Regardless of how "cool" drugs may look, there is nothing glamorous about the reality of addiction, a miserable experience for the addict and everyone around him. Addiction causes an all-consuming craving for drugs, leading an otherwise responsible, caring person to destroy relationships, work, and family life.

Certified drug and alcohol counselors work with families to find the program best suited to a child's needs. To find a good certified counselor you can consult your child's doctor, other parents whose children have been treated for drug abuse, the local hospital, a school social worker, the school district's substance abuse coordinator, or the county mental health society.

You can also call the U. S. Dept. of Health and Human Services Center for Substance Abuse Treatment (800) 662-HELP for referrals. Counselors will discuss treatment options such as individual or group out-patient programs, prescription medication, and residential programs. Counselors may also have information on whether a particular treatment center will accept third-party, partial or no payment for services. (Some residential centers reserve a number of government-financed beds for patients who are unable to afford treatment.) Counselors may also be able to suggest support groups that can steer families to sources of funding such as local church programs.

Jamal,* 17, treatment client in a residential program in Encinitas, California:

"My mom and dad are both addicts. When I was 15, I was living with my uncle, and we got into a fight. I went to stay overnight at a friend's, and he was using marijuana. So we got high on pot. But pot got old, and a bunch of us went to our dealer's house, gave him all the money we had, and he bought hard liquor for us. It made me feel on top of the world, and alcohol became my drug of choice.

"I started ditching school, and I got suspended. I only went to get high anyway. But now I couldn't graduate. I was living with my grandmother at the time, and a peer counseling teacher from school recommended a residential treatment center.

"When I got here, I didn't think I'd stay. I thought I'd just come to cool down. But they started forcing me to change. The staff made me see that I was out of control. In about six months, I started changing. The counselors threw my issues in my face — I had been molested and abused when I was young, and I had had problems with my mom. I made commitments that I had to keep. I plan to graduate and move back to New York, and I hope to attend college.

"My advice to anyone doing drugs is that if you feel vulnerable, find someone — your best friend or someone you know who cares — and do what is hardest: Talk about your pain. The people who take care of you shouldn't be dictators too; they should share their own experiences and let kids know that they're there for them. I wish my parents had talked to me about their own drug problems."

* name changed

Andrea M.*, married; a New Jersey mother of a daughter, 16, and son, 18:

"Both my kids were fun-loving and good students, but when my son was almost 16, his behavior changed. He was having trouble in school, he found a different set of friends, his personal appearance suffered, he slept all day and he was wide awake all night. I thought this was just typical teenage stuff. I didn't notice any changes in my daughter, but it turns out that she had started around the same time and was just better at hiding her drug abuse.

"We began getting phone calls at night, and my money started disappearing, but my husband and I disagreed about what to do, so we did nothing. Finally, about a year ago, my son and daughter got caught together trying to sell tabs of acid to the police in a sting operation.

"They both received two years' probation, which is mandatory in our state for a first drug offense. My husband decided that day that our kids needed a full-force intervention program, so we brought them to a treatment facility not too far from our home in the suburbs. Both kids attended sessions there several times per week after school. We were shocked to learn that they had been using drugs much more than we'd ever imagined — marijuana, acid, crystal meth and Ketamine.

"The parents attend the program on a regular basis, too. We learn the three C's: that 'you didn't Cause, can't Control and can't Cure' your kids' problems. But you can't ignore the problems because they won't go away by themselves.

"My daughter graduated from the program first. She's clean and has a boyfriend and is working on her SATs so she can go to college the year after next. My son lives at home, too, and is trying to juggle the commitments of a girlfriend, work, and college. They both go to Narcotics Anonymous meetings, which is a continuation of the treatment program. We're relieved, but we still take it one day at a time."

* name changed