Evidence for the pathological right-handedness hypothesis

Area of Science:

• Neuroscience
• Epileptology
• Human Behavior

Background:

• Temporal lobe epilepsy (TLE) is a neurological disorder affecting brain function.
• Handedness, the preference for using one hand over the other, is a complex trait influenced by brain lateralization.
• The relationship between TLE and handedness, particularly the concept of pathological handedness, requires further empirical investigation.

Purpose of the Study:

• To investigate the association between handedness and TLE in a Korean cohort.
• To examine if TLE influences the incidence of left-handedness and right-handedness.
• To provide empirical evidence for the pathological right-handedness hypothesis.

Main Methods:

• A comparative study design was employed.
• Handedness was assessed in 109 Korean patients diagnosed with TLE.
• Handedness data from 120 healthy Korean control participants were used for comparison.

Main Results:

• Left TLE showed a significantly higher incidence of left-handers compared to controls.
• Right TLE demonstrated a significantly higher incidence of strong right-handers compared to controls.
• These findings support the notion that early right-brain damage can lead to pathological right-handedness.

Conclusions:

• The study provides the first empirical evidence supporting the pathological right-handedness hypothesis.
• Right TLE may induce a shift towards strong right-handedness due to early right-brain damage affecting left-hand function in natural weak right-handers.
• Previous failures to detect pathological right-handedness might be attributed to the low prevalence of natural left-handers.