Hepatitis C, Drug Dependency Lend to Cortical Volume Deficit in Alcoholics

George F. Koob, PhD

Cortical volume deficit in adults with alcohol dependence is accelerated by drug dependence or hepatitis C virus (HCV) infection comorbidity, according to a new study.

A team of California-based researchers conducted a cross-sectional, longitudinal study of magnetic resonance imaging (MRI) data from April 2003 to March 2017. The 826 structural MRI images were collected for 421 participants — 222 being individuals with alcohol dependence, and 199 being age-controlled matches, parcellated with a common atlas, and adjusted for brain volume.

Of the participants, longitudinal data were available on 116 participants with alcohol dependence and 96 control participants. Researchers were gauging the prevalence of comorbidities such as drug dependence and HCV infection with cortical volume deficit in patients with and without alcohol dependence. They noted that it’s been established through previous documented neuroimaging and postmortem analysis that chronic alcohol consumption can cause brain shrinkage.

A new assessment of the association between alcoholism and brain structure is emphasized by current data indicating a major increase of 106.7% in alcohol use disorder (AUD) in the US population aged 65 years or older. Such an increase would affect 3.1% of that population.

Researchers also noted an increasing AUD prevalence in younger adults — from 44.4% in persons aged 18 to 29; 47.7% in persons aged 30 to 44; and 81.5% in persons aged 45 to 64. Despite this, current research lacks focus on the longitudinal change of regional cortical volume in large samples of adults with alcohol dependence.

The alcohol-dependent patient population was mostly men (70.3%), with a mean age of 48 years. They reported mean volume deficits in the frontal (t= -5.732, P < 0.001); temporal (t= -3.151; P — 0.002); parietal (t= -5.063; P < 0.001); cingulate (t= -3.170; P = 0.002); and insular (t= -4.920; P < 0.001) cortices. Researchers noted the deficits were more prominent in the front subregions, and were not sex-dependent.

Alcohol-dependent participants with HCV comorbidity were shown to have greater deficits in the frontal, precentral, superior, and orbital volumes. Because the alcohol-dependent group reported a drug-dependence incidence of 54.5%, researchers examined subgroups of drug-dependent participants with alcoholism. Participants with alcohol and cocaine dependence, as well as alcohol plus opiate dependence, reported smaller frontal volumes than the participants with alcoholism but no drug dependence.

Researchers concluded that both drug dependence and HCV infection were compounding elements to alcohol dependence’s effect on frontal cortical volume. They also speculated that older adults are at a greater risk of frontal cortex effects due to alcohol — even if they begin alcohol consumption at an older age.

In an accompanying editorial to the study, George F. Koob, PhD, of the National Institute on Alcohol Abuse and Alcoholism, prosed that the frontal cortical deficits associated with aging could also influence impulsivity and compulsivity in older people — therefore increasing their risk of developing AUD.

Because of this, excessive alcohol consumption could accelerate aging, and aging may enable the AUD process through a “two-way pathophysiological interaction.”

“In short, excessive drinking in the elderly population may tap into misdirected attempts at self-regulation in which an individual takes the drug to fix the problem that the drug caused,” Koob wrote.

HCV is a comorbidity 5 times as prevalent in the baby boomer generation than other age groups. Though it may not be as frequent as the infectious disease, AUD is a condition that must be watched for in the older population.

“Given the rapidly growing aging population the United States, it is critical that we improve and implement strategies to address alcohol misuse among older drinkers,” Koob wrote.

The study, "The Role of Aging, Drug Dependence, and Hepatitis C Comorbidity in Alcoholism Cortical Compromise," was published online in JAMA Psychiatry last month.