Genetics and Age Change Attention Disorders

Adult attention deficit hyperactivity overview

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) So what exactly is ADHD? And what, if anything, is the difference between ADHD in childhood and ADHD in adulthood?

A study review released this week by the journal Molecular Psychiatry attempts to answer this question in scientific detail. Observing many past studies, the review analyzes everything from genetics to adopted relatives to examine the intricacies of ADHD.

"Speak with your doctor if exhibiting signs of ADHD. "

Thirteen doctors and researchers from three continents came together to administer this review, citing the work of over 250 past studies and research reports.  Although the review covered details of ADHD in its entirety, it was focused on the maturation of ADHD into adulthood.  

Attention deficit hyperactivity disorder (ADHD), as suggested, is a disorder characterized by inattentive behavior and hyperactive energy, which may cause difficulty in many areas of life. Although childhood ADHD (cADHD) tends to get more publicity, adult ADHD (aADHD) has become increasingly prevalent with more adults suffering than children.

ADHD affects three to five percent of adults, making it one of the most common disorders of our time.

Clinical studies used to determine the difference between childhood and adult ADHD found that although adults typically demonstrate less hyperactivity and impulsivity, their inattentive symptoms become more prevalent over time.

Also, ADHD’s comorbidity with other psychiatric disorders increases with age.

Studies more commonly highlight childhood ADHD than adult ADHD. As a result, doctors often find the need to use children’s studies to infer conclusions regarding adults. 

Twin studies aided researchers in understanding high heritability (70-80 percent) as well as a strong correlation between a continuity of symptoms and genetics. A four-year follow-up study found similar patterns, with higher risks of ADHD in the relatives of those whose symptoms persisted from youth into adolescence.

Such conclusions led past researchers to begin administering family studies for ADHD where clustering was found within and across generations. A sibling of a childhood ADHD patient's risk was around 15 percent, while siblings of an adult with ADHD have a 41 percent risk of developing the disorder. Moreover, offspring of aADHD holders possess a 57 percent chance of inheritance.

Environmental effects appeared to be inconsequential, as adoption studies showed that ADHD was limited to biological relatives, further implicating genetic impact.

The review ends looking into 46 molecular genetic studies with concurrence in opinion, implicating both coinciding and differentiating genes within childhood and adult ADHD. Linkage studies identified particular loci for aADHD, as well as associative genes LPHN3 and CDH13.

Rare genetic variations identified gene mutations as possible causal features. 

The study’s author notes, “Progress in identifying aADHD risk genes may provide us with tools for the prediction of disease progression in the clinic and better treatment, and ultimately may help to prevent persistence of ADHD into adulthood.”

Reviewed by: 
Review Date: 
November 23, 2011
Last Updated:
October 2, 2012