EEG spectral phenotypes: heritability and association with marijuana and alcohol dependence in an American Indian community study.

Department of Molecular and Integrative Neurosciences, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
Drug and alcohol dependence (Impact Factor: 3.28). 09/2009; 106(2-3):101-10. DOI: 10.1016/j.drugalcdep.2009.07.024
Source: PubMed

ABSTRACT Native Americans have some of the highest rates of marijuana and alcohol use and abuse, yet neurobiological measures associated with dependence on these substances in this population remain unknown. The present investigation evaluated the heritability of spectral characteristics of the electroencephalogram (EEG) and their correlation with marijuana and alcohol dependence in an American Indian community. Participants (n=626) were evaluated for marijuana (MJ) and alcohol (ALC) dependence, as well as other psychiatric disorders. EEGs were collected from six cortical sites and spectral power determined in five frequency bands (delta 1.0-4.0 Hz, theta 4.0-7.5 Hz, alpha 7.5-12.0 Hz, low beta 12.0-20.0 Hz and high beta/gamma 20-50 Hz). The estimated heritability (h(2)) of the EEG phenotypes was calculated using SOLAR, and ranged from 0.16 to 0.67. Stepwise linear regression was used to detect correlations between MJ and ALC dependence and the spectral characteristics of the EEG using a model that took into account: age, gender, Native American Heritage (NAH) and a lifetime diagnosis of antisocial personality and/or conduct disorder (ASPD/CD). Increases in spectral power in the delta frequency range, were significantly correlated with gender (p<0.001) and marijuana dependence (p<0.003). Gender, age, NAH and ASPD/CD were all significantly (p<0.001) correlated with theta, alpha and beta band power, whereas alcohol dependence (p<0.01), gender (p<0.001), and ASPD/CD (p<0.001) were all correlated with high beta/gamma band power. These data suggest that the traits of EEG delta and high beta/gamma activity are correlated with MJ dependence and alcohol dependence, respectively, in this community sample of Native Americans.

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Moderating factors such as health status, education level, quality of life, socioeconomic status, cultural identification, and historical trauma may contribute to use of alcohol and other drug (Szlemko, Wood, & Thurman, 2006). These findings add to the sparse collection of available literature on AOD use among AI/AN populations Methods: Six hundred male and female adult, Northern Plains Indians were recruited from IHS and tribal behavioral health clinics on seven North and South Dakota Reservations to complete a series of mood disorder assessments. The participants were recruited from three groups: 1) diagnosed depressed (by clinician), 2) diagnosed anxious (by clinician), and 3) no mental health diagnosis (control). Assessments were completed by paper and pencil, placed in an envelope and returned to the site coordinator. Participants received $10 in gift/gas cards in compensation for their time and the tribes received $5/participant for compensation. Site coordinators added the clinical diagnoses to the envelopes and returned them in separate envelopes from the consent forms to the researchers. Data was then entered using SPSS for all returned measures. Assessments included depression, anxiety, hopelessness, rumination, culture, quality of life, substance abuse, substance use, demographics, and the clinician’s diagnosis code. Results: A total of 600 participants from eight approved sites completed assessments: 233 males and 360 females between the ages of 18 and 80 years with a mean age was 36.2 years with a standard deviation of 12.7 years. Seventy-nine percent of participants had at least a high school education and 54% had household incomes below $8,000/year, 55.6% were single, and 37.9% are currently unemployed. As expected alcohol (52%) and cigarette (65.3%) usages were the most common type of substances used by NPI and the general population (55.2%; 20.6%) and AIAN as a group (43.9; 23.2%). Participants with no mental health diagnosis used tobacco less in the past month than those who have mental health diagnosis (56.4% vs. 76%). More of those with a mental health diagnosis smoked frequently (62.1%) than those with no mental health diagnosis (38.9%). Similarly, those with mental health diagnoses used alcohol in the past month more than those with no mental health diagnosis (48 vs.38.5%). This was also true of binge alcohol drinking (45.5% vs. 30.8%) Participants with a mental health diagnosis were twice as likely to use marijuana in the past month compared to those having no diagnosis (16.2% vs. 8%). Age groupings were examined: 18-25 years old smoked marijuana (13.4%) more than any other age group, 31-35 years old had the highest cocaine usage (14.3%) 36-40 year olds had the highest methamphetamine usage (16.3%). All substance use decreases in participants over the age of 45. Further Findings: 1) Male>Female use in all AOD categories, except methamphetamine where both groups have similar use at about 21%. 2) Participants with a diagnosed mental health problem used more AOD (48%) than those with no mental health diagnosis (38.5%). 3) Younger adults use more AOD than older adults with dramatic decrease after 45 years of age. 4) Marijuana use peaks in the 18-25 age group, cocaine peaks in the 31-35 age group, and methamphetamine peaks in the 36-40 age group. 5) Illicit drug use among AI/AN nationally were higher than the general population (18.3% vs. 8.8%). 6) Current alcohol use among NPI is lower than general population (16.8 % vs. 56.7%). AI/AN nationally (37.1%), is higher than NPI, and lower than the general population. 7) Binge drinking of alcohol among NPI is than lower than general population (11.2% vs. 24.8%). Rates of AI/AN nationally (22.2%), is higher than NPI, and but lower than the general population. 8) Tobacco Use among NPI is than lower than general population (21.6 % vs. 29.6%). AI/AN nationally (41.8%), is higher than NPI and the general population. References: Ehlers, C., Phillips, E., Gizer, I., Gilder, D., & Wilhelmsen, K. (2010). EEG spectral phenotypes: Heritability and association with marijuana and alcohol dependence in an American Indian community study. Drug and Alcohol Dependence, 106(2-3), 101-110. doi:10.1016/j.drugalcdep.2009.07.024. Szlemko, W., Wood, J., & Thurman, P. (2006). Native Americans and Alcohol: Past, Present, and Future. Journal of General Psychology, 133(4), 435-451. doi:10.3200/GENP.133.4.435-451. Substance Abuse and Mental Health Services Administration, Office of Applied Studies. (June 24, 2010). The NSDUH Report: Substance Use among American Indian or Alaska Native Adults. Rockville, MD. Retrieved from This research supported by grant # U26IHS300127 from IHS and NIDA. The University
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