In the present study, researchers examined the effects on the brain of the 2-month treatment with methylphenidate extended-release formulation (OROS-MPH) using [Tc-99m] TRODAT-1SPECT in a sample of treatment-naïve adolescents with Attention Deficit/Hyperactivity Disorder (ADHD)
In addition, to assess whether risk alleles (homozygosity for the 10-repeat allele at the DAT1 gene were associated with alterations in striatal DAT availability.
Twenty adolescents with ADHD underwent brain single-photon emission computed tomography (SPECT) scans with [Tc-99m] TRODAT-1 at baseline and two months after starting OROS-MPH treatment with dosages up to 1?mg/kg/day.
The severity of illness was estimated using the Clinical Global Impression Scale (CGI-S) and DuPaul ADHD Rating Scale-Clinician version (ARS) before treatment,1?month and 2?months after initiating OROS-MPH treatment.
Decreased DAT availability was found in both the right caudate (pretreatment DAT binding: 224.76?±?33.77, post-treatment DAT binding: 208.86?±?28.75, p?=?0.02) and right putamen (pre-treatment DAT binding: 314.41?±?55.24, post-treatment DAT binding: 285.66?±?39.20, p?=?0.05) in adolescents with ADHD receiving OROS-MPH treatment.
Adolescents with ADHD who showed a robust response to OROS-MPH (n?=?7) had the significantly greater reduction of DAT density in the right putamen than adolescents who showed the less robust response to OROS-MPH (n?=?13) (p?=?0.02).
However, between-group differences by treatment responses were not related with DAT density in the right caudate. Risk alleles (homozygosity for the 10-repeat allele of DAT1 gene) in the DAT1 gene were not associated with alterations in striatal DAT availability.
Two months of OROS-MPH treatment decreased DAT availability in both the right caudate and putamen. Adolescents with ADHD who showed a robust response to OROS-MPH had the greater reduction of DAT density in the right putamen.
However, our findings did not support an association between homozygosity for a 10-repeat allele in the DAT1 gene and DAT density, assessedusing[Tc-99m] TRODAT-1SPECT.