Substance Abuse

Note: methodological problems are common in studies of neuropsychological outcome of substance use due to high rate of co-morbidities and polysubstance use.


Acute Effects

  • One of the most widely investigated and abused illicit drugs in the US.
  • High doses can create rapid motor activity, rambling speech, impaired judgment, paranoid and psychotic behavior, irritability, and anxiety.
  • EEGs show marked reduced Alpha power in frontal and temporal regions.

Prenatal Cocaine Exposure

  • Newborn infants who are exposed to cocaine in utero are more likely to have reduced gestational age, length, and head circumference. Low birth weight has also been implicated in some studies.
  • Often behavioral or temperamental problems emerge, typically by age 3.
  • Cocaine exposed infants can show increased tone and motor activity, jerky movements, startles, tremors, back arching and signs of CNS and visual stress. Also reported are difficulties with auditory skills, excitability, and lethargy.
  • Heavily cocaine-exposed infants show more jitteriness and attentional problems compared to lightly and non-exposed infants.
  • Longitudinal studies of prenatally exposed toddlers and preschoolers typically show low average to average cognitive abilities but tend to be highly distractible and can have significant difficulties with speech and language development, peer interactions, and fine motor coordination.

A few longitudinal studies

  • Cocaine use within 72 hours (acute) is associated with specific neuropsychological impairments, including deficits in memory, visual-spatial processing, and concentration.
  • After two weeks of abstinence, deficits are noted in the areas of psychomotor speed, memory, and concentration.
  • These deficits are consistent with deficits seen in dopamine depletion disorders such as Parkinson’s and progressive supranuclear palsy.
  • Problems with planning and impulsivity have also been reported.
  • CT studies show evidence of cerebral atrophy in chronic users.


  • Stimulant toxicity may include repetitive teeth grinding, skin picking, perseverative speech or behavior, preoccupation with one’s own behavior and mental activity, suspiciousness, paranoia with auditory and visual hallucinations, hyperactivity, confusion, convulsions, and even life-threatening conditions such as cardiovascular collapse and high fever progressing to death.
  • Withdrawal from stimulants can produce extreme depression, fatigue, extreme somnolence, and apathy. Persistent mood and anxiety problems may last for several months.
  • Neuropsychological studies indicate symptoms associated with CNS damage, including disruptions in memory, concentration, and abstract reasoning.
  • Exposure of infants to methamphetamines prenatally produces similar symptoms as are found in cocaine exposed babies. These include lethargy, tremor, and increased intraventricular hemorrhage.


  • Associated with low birthweight, miscarriage, prematurity, microcephaly, and intrauterine growth retardation.


  • Associated with spontaneous abortions, premature rupture of membranes, preterm delivery, perinatal death, low birth weight, and deficits in learning and behavior.


  • A CNS depressant.
  • Impairment in visual-motor skills, integration of sensory stimulation, and information processing become apparent at blood levels of 100 mg (about the point when one feels intoxicated).
  • Higher blood levels eventually can result in sedation, CNS depression, stupor, and even coma. *Tolerance and physical and psychological dependence develop over time with diagnosable alcoholism; this diagnosis can usually be made after 3 to 15 years of prolonged use.
  • Rarely do children or adolescents experience seizures, hallucinations, or the DT’s which are frequently experienced by adult users.

Outcomes Following Alcohol Cessation

  • Following cessation, older subjects show improvement after prolonged alcohol use but remain in the impaired range on a variety of neurocognitive tests.
  • This is not the same for younger individuals under the age of 35 to 40 who usually return to normal performance levels within about one month after cessation.
    • This is at least the finding in younger alcoholics who have drank six years or less.
  • After initial sobriety, alcohol dependence in younger adults (ages 18 through 35) have found few deficits in language skills, attention, motor skills, intelligence, memory, and executive functions.

Neuroimaging Findings

  • Neuroimaging studies have demonstrated that chronic alcoholism in older adults produces widespread brain damage, but such evidence has not been apparent with children and younger adults.
  • The frontal lobes are uniquely sensitive to alcohol abuse although postmortem studies have implicated temporal and parietal lobes as well.
  • Clinical signs associated with damage to frontal cortex associated with alcohol abuse include emotional apathy, disinhibition, poor attention, and abnormal perseverative responding.
  • Drug abuse combined with heavy alcohol use, which is often typical, show significantly smaller cerebellar vermes. White matter changes can also occur.

Glue Sniffing

  • Neuropsychological deficits include abnormalities in attention, memory, visual-spatial functions, complex cognition, naming, and problems with reading or writing. Deficits in manual dexterity, visual scanning, and verbal memory have also been reported.
  • Neuropsychological deficits appear to be dose related.
  • In one study, diffuse atrophy of cerebral hemispheres, cerebellum and, in severe cases, the brainstem were evident in 88.8% of subjects studied.
    • Of note, this study was confounded because of polysubstance (e.g., amphetamines, marijuana, and alcohol) use.


  • Research is limited but take home message is that there is a dose-response relationship, with greater marijuana use resulting in greater deficits.
    • Memory appears to be the most significant cognitive area affected, and memory efficiency has been noted as the primary difficulty, at least during active marijuana use.
  • In long-term users (>30 years):
    • Neurocognitive problems were noted in sustained attention (a continuous performance test).
    • Short-term memory effects have also been reported, although these have been described as subtle or subclinical.
  • In younger adults, MRI studies have shown evidence of cerebral changes, including large left lateral ventricles, temporal lobe dilation, and damage to the caudate nucleus and basal ganglia.
    • The subjects in the above imaging study were users for a period of 3 to 11 years, but polysubstance use was again a confounding factor.