Effects of caffeine on cerebral blood flow.

Objective: The objective of the present study is to evaluate whether, after caffeine ingestion, there are variations in blood velocity of the middle cerebral arteries in clinically healthy young people as well as to evaluate whether this variation is dependent on the administered dose.

Methods: We used transcranial Doppler ultrasonography to record blood velocities of the middle cerebral arteries in three groups of 15 clinically healthy young adults each: no caffeine, a45 mg, and 120 mg of caffeine groups. Transcranial Doppler ultrasonography provided simultaneous bilateral velocity of the middle cerebral arteries measurements while participants performed functional tests (hyperventilation and hypoventilation orders) and three cognitive activities (test 1, short-term memory; test 2, solving a vocabulary problem; and test 3, solving a math problem) each in 31-s tests with 1-min rests between them.

Prevalence of Self-Medication in Portuguese Adolescents.

Self-medication is considered one of the health-risk behaviours found among adolescents. The main objective of this study is to determine the prevalence of self-medication for Portuguese adolescents. An observational cross-sectional study was carried out.