Brief report: plasma leptin levels are elevated in autism: association with early onset phenotype?

Probst et al. (2008) drew blood from kids with autism and from kids without. They checked leptin levels in the plasma. Leptin is a hormone that tells the brain when the stomach is full.

The team looked at two autism groups: early-onset and later-onset. They wanted to know if timing changed the result.

Children with early-onset autism had much higher leptin than typical peers. The later-onset group also showed higher levels, but the jump was biggest in the early-onset kids.

The finding points to a possible blood marker for a specific autism subtype.

The result lines up with older plasma work. Davison et al. (1984) saw cyclic AMP double in autism. Aldred et al. (2003) found high amino acids in autistic children and their parents. Each study flags a different molecule, but all show autistic plasma looks different.

Hu et al. (2018) and Siniscalco et al. (2012) add immune pieces. They report high cytokines and high caspase in autistic kids. Leptin is also immune-linked, so the plasma pattern keeps growing.

Schneider et al. (2006) review shows one-third of autistic kids have high serotonin. No contradiction here: leptin, serotonin, and immune signals can all be high at once. Together they build a picture of wide biochemical change, not a single cause.

You cannot treat leptin yet, but you can track it. High leptin may nudge you to check diet, sleep, or weight gain in early-onset clients. Share the number with the child's doctor; it may guide further metabolic screening. Keep watching for follow-up studies that link this marker to intervention response.