Aggressive growth funds are only for non risk-averse investors willing to accept a high risk-return trade-off.
Aggressive growth funds have large betas, which means they have a large positive correlation with the stock market. They tend to perform very well in economic upswings and very poorly in economic downturns. An aggressive growth fund may also invest in a company's IPO and then quickly turn around and re-sell the same stock to realize large profits. Some aggressive growth funds also invest in options to boost returns.